In-ear headphone device with active noise control

Abstract

An in-ear headphone device for insertion into a human ear canal. The in-ear headphone device includes a noise microphone, a loudspeaker, and a signal processor configured to provide an active noise control signal based on a recorded audio signal from the noise microphone, the loudspeaker configured to play the active noise control signal within the ear canal. The device further includes an attenuated vent including one or more vent elements and one or more damping elements, the attenuated vent configured to couple the ear canal to an external acoustic environment. The attenuated vent is characterized by an inward vent transfer function (HVI) from the external acoustic environment to the ear canal. The attenuated vent is configured to attenuate acoustic resonance of the one or more vent elements such that the magnitude of the resonance of the inward vent transfer function (HVI) of the attenuated vent within a resonant frequency range of 100 Hz to 2 kHz is at most 3 dB greater than a reference magnitude of the inward vent transfer function (HVI) within a reference frequency range of 20 Hz to 100 Hz.

Description

[Technical Field]

[0001] The present invention relates to an in-ear headphone device configured to provide active noise control. [Background technology]

[0002] The field of in-ear headphone devices has advanced rapidly, particularly due to the increasing capabilities of digital electronic devices. One key capability of headphone devices is their ability to provide active noise control, a feedback process in which a microphone records sound and a loudspeaker rejects this sound by utilizing the principle of destructive interference. As a result, unwanted noise from, for example, a noisy external environment can be significantly reduced within the ear canal of a user of such a device.

[0003] However, in-ear headphone devices, especially those configured to provide active noise control, suffer from several problems that impair the functionality of the device. One example is dynamic acoustic leakage, which occurs when the user is active, most notably during jaw movement, opening small air passages from the external environment to the ear canal and disrupting the normally tight barrier. Such leakage not only introduces increased and unwanted noise, but can also significantly distort the sound reproduction provided by the active noise control and loudspeakers.

[0004] Despite the computing power accommodated by modern electronic devices, rapidly changing conditions such as those presented by dynamic acoustic leakage cannot be adequately managed within the confines of digital signal processing without significant distortion to the user. Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have identified the above-mentioned problems and challenges associated with active noise control in in-ear headphones and have subsequently created the invention described below, which is able to reduce some of the drawbacks of known techniques. [Means for solving the problem]

[0006] The present invention relates to an in-ear headphone device for insertion into a human ear canal, the in-ear headphone device comprising: a noise microphone; a loudspeaker; and a signal processor configured to provide an active noise control signal based on a recorded audio signal from the noise microphone, the loudspeaker configured to reproduce the active noise control signal in the ear canal, the in-ear headphone device comprising an attenuated vent comprising one or more vent elements and one or more attenuation elements, the attenuated vent configured to couple the ear canal to an external acoustic environment, the attenuated vent having an inward vent transfer function H from the external acoustic environment to the ear canal. VI and the damped vent is characterized by the inward vent transfer function H of the damped vent within a resonant frequency range of 100 Hz to 2 kHz. VI The magnitude of the resonance of the inward vent transfer function H VI The present invention relates to an in-ear headphone device configured to attenuate acoustic resonance of the one or more vent elements to be at most 3 dB greater than a reference magnitude.

[0007] An in-ear headphone device may be understood as a headphone device configured to be worn by a user by fitting the device within the user's outer ear, such as within the concha next to the ear canal. An in-ear headphone device may also extend at least partially into the user's ear canal. An in-ear headphone device may typically be shaped to fit at least partially within the outer ear and / or ear canal, thereby ensuring that the device fits into the user's ear. An in-ear headphone device may also be understood as an in-ear headphone, earplug, in-ear headphone, earbud, or hearable.

[0008] In-ear headphones can, for example, enable a user to listen to an audio source with minimal noise disturbing the surroundings. Thus, the application areas of in-ear headphones can be, for example, listening to media, performing telecommunications, performing hearing aids, speech intelligibility enhancement, and active noise control.

[0009] An in-ear headphone device according to the present invention comprises a noise microphone, a loudspeaker, and a signal processor configured to provide active noise control in combination with the loudspeaker based on sounds recorded by the noise microphone.

[0010] Sound can be understood as an audible acoustic pressure wave. A loudspeaker can produce sound by accepting a drive signal, e.g., an alternating current, which generates a reciprocating motion of a part of the loudspeaker, e.g., a diaphragm, to push air and thus reproduce the accepted drive signal as sound. In the reverse manner, a microphone can convert sound into an electrical signal based on the voltage and / or current as pressure waves reciprocate through a moving part of the microphone, generating an electrical signal.

[0011] Active noise control can be understood as a method for reducing unwanted sounds by adding an active noise control sound with an opposite sound pressure compared to the unwanted sound. Active noise control may also be referred to as active noise reduction or active noise cancellation and may be considered a type of feedback.

[0012] To provide active noise control, an estimate or representation of the unwanted sound is required in order to produce an opposing sound. For this purpose, a noise microphone comprising one or more microphones is provided to record the representation of the unwanted sound. The noise microphone can be positioned to primarily record sounds from the user's ear canal, i.e. to measure more or less directly the unwanted sound as it would be perceived by the user, or to primarily record sounds from the environment around the user, i.e. from the external acoustic environment, which will measure the unwanted sound as it would be perceived by the user, using the inward transfer function H of the headphone device. TI It will be appreciated that an embodiment may also have a distributed noise microphone comprising both an external and internal microphone within the same device.

[0013] Based on the recorded sound from the noise microphone, an active noise control signal can be generated, which, when reproduced by a loudspeaker, is preferably designed to cancel the unwanted sound in the user's ear by destructive interference. Preferably, this signal is the additive inverse of the unwanted sound and can therefore be derived from the unwanted sound, for example, by reversing the phase, reversing the polarity, or taking the additive inverse. Furthermore, the active noise control signal is also preferably adapted to account for the non-ideal frequency responses of actual microphones, loudspeakers, signal processing, etc., so that the reproduced sound is as close to the inverse phase of the unwanted sound as feasible. Furthermore, in practice, the active noise control can preferably be limited to a specific frequency band, for example, audible frequencies below 1 kHz.

[0014] The active noise control signal can be played by a loudspeaker in a headphone to generate an active noise control sound, thus canceling out unwanted sounds in the user's ear. The same loudspeaker can simultaneously emit another audio signal, e.g., music or speech, that preferably cannot be substantially affected by the active noise control. The audio signal emitted by the loudspeaker, e.g., music or speech, that is not emitted for purposes of active noise control can be referred to as the desired audio signal.

[0015] Active noise control is often combined with passive noise control, which can typically be understood as sound reduction through noise-blocking materials. In-ear headphone devices that do not substantially have passive noise control typically may not be able to generate enough active noise control sound to adequately cancel unwanted sounds. Therefore, in-ear headphone devices configured to provide active noise control are typically configured to provide a nearly airtight barrier between the ear canal and the external environment. This may be achieved, for example, by a flexible tip configured to provide acoustic sealing.

[0016] In fact, it is not possible to achieve an airtight barrier within an in-ear headphone device, especially due to the irregularities in the ear geometry, and especially during jaw movements. Even with a tip that is as flexible as practical, taking durability, cost, etc. into account, there will almost always be some leakage sound past the headphone device and into the ear canal. Due to this dynamic nature of the noise transfer function, active noise control uses a changing inward total transfer function H TI This requires continuous adaptation of the algorithm to produce an active noise control signal that matches the actual noise. This continuous adaptation may further require frequent changes of the filter coefficients with each filter update during changes in leakage, which often results in a mismatch of the active noise control signal compared to the actual noise, resulting in audible artifacts.

[0017] The transformation that sounds of different frequencies undergo as they propagate from one point to another can be described by a transfer function H(s). The transfer function describes the efficiency of the propagation, for example by the magnitude or absolute value G of the transfer function, and can also describe the phase shift Φ that the sound undergoes. The phase shift is determined by the group delay τ g where group delay is the negative of the derivative of the phase shift Φ with respect to frequency, accounting for the change in time delay between different frequencies during propagation.

[0018] In the context of in-ear headphone devices, the transfer function that describes how sound is affected as it propagates from the external environment into the ear canal is the inward total transfer function H TI Preferably, the active noise control of the in-ear headphone device is performed using this inward total transfer function H TI For example, frequencies at which noise is efficiently transmitted through the device require a larger amplitude active noise control signal to be cancelled in the user's ear canal than frequencies at which noise is inefficiently transmitted.

[0019] Furthermore, the total inward transfer function H TI has an associated phase shift / group delay that describes the degree to which frequencies are delayed when transmitted from the external environment to the ear canal. Preferably, the active noise control is designed to function according to this group delay, e.g., if a frequency is transmitted with a large group delay, the corresponding active noise control signal must be delayed accordingly.

[0020] As explained above, active noise control relies on the signal recorded by the noise microphone to generate the active noise control signal. However, the noise microphone may also record any sound of the desired audio signal that escapes the ear canal through leakage through the headphone device and / or through the headphone device itself. This can cause an undesirable feedback effect that may be referred to as loudspeaker feedback. Loudspeaker feedback can be addressed and eliminated by performing appropriate signal processing, based on the fact that the processor has at least a rough idea of ​​what the loudspeaker is producing. To do so, a well-characterized transfer function is needed that describes the efficiency with which sound is transmitted from the ear canal to the external environment, specifically to the microphone or microphones. This transfer function is called the outward total transfer function H TOIt can be referred to as.

[0021] The inventors have identified several problems and challenges that have a substantial negative impact on the performance in some or all use cases of typical in-ear headphone devices configured to provide active noise control. These salient issues are next introduced in detail. Counterintuitive and straightforward solutions to these problems are then presented as they have been devised and developed by the inventors.

[0022] A common problem with in-ear headphone devices with acoustic sealing is the occlusion effect, which occurs when the ear canal is blocked and is most noticeable when the user speaks. The user's own speech may be carried by bones and tissue in the form of vibrations, which then vibrate the ear canal and cause sound pressure within the ear canal. This sound pressure, especially at low frequencies, is greatly increased when the ear canal is occluded / blocked by the headphone device. Thus, users experience a dull, muffled, buzzing, echoey, or distorted reproduction of their own voice when speaking and wearing an occlusive device.

[0023] The occlusion effect of in-ear headphone devices can be suppressed by vents, i.e., channels or ducts, configured to couple the ear canal to the external environment. Note, however, that this is not a reasonable element to incorporate into in-ear headphone devices configured to provide active noise control for several reasons. In particular, such devices rely on passive noise control, and vents typically allow noise to propagate fairly easily through the headphones into the ear canal, thereby compromising passive noise control.

[0024] Furthermore, the addition of a vent introduces Helmholtz resonance when the device is worn. Helmholtz resonance is a resonance phenomenon that can occur when a cavity, such as the ear canal, is acoustically coupled to the surrounding environment by a port or neck, such as a vent. When the air or air mass within the neck is displaced, the pressure within the cavity is affected, acting as a restoring force on the air mass within the neck. Thus, when displaced, the air mass within the neck may oscillate at a natural frequency that may be understood as the characteristic frequency of the Helmholtz resonance of the system.

[0025] Thus, in-ear devices with vents may introduce Helmholtz resonance, often with a characteristic frequency in the audible range, e.g., around 1 kHz, into the user's ear canal when the device is worn. As a result, the user experiences undesirable amplification of sound at this characteristic frequency. In-ear headphone devices configured to provide active noise control may be unable to properly provide active noise control at this characteristic frequency.

[0026] Furthermore, the acoustic reproduction of a desired audio signal, for example music or telecommunications, can be significantly distorted by the presence of acoustic Helmholtz resonance in a frequency range near the characteristic frequency of the Helmholtz resonance.

[0027] Additionally, vents configured to reduce the occlusion effect by allowing low-frequency noise to escape from the ear canal also allow sounds in the bass frequency regime of desired audio signals, such as music, to leave the ear canal. As a result, acoustic reproduction of desired audio signals in the bass frequency regime is degraded. Often, the bass reproduction capabilities of very small loudspeakers available in in-ear headphone devices have traditionally been less than ideal, and they are unable to reproduce bass at an amplified level to counteract the bass-degrading effect of the vent.

[0028] Another problem with in-ear headphone devices is associated with the variable shapes and sizes of different users' outer ears. One user's ear canal, for example, may have a different volume than another user's ear canal. Furthermore, when an in-ear headphone device is inserted into a user's ear, it may not be inserted in exactly the same position every time. These variables, which may be referred to as user variability, may affect the performance of the in-ear headphone device, for example, in the bass frequency regime.

[0029] The user fluctuation is calculated by the inward total transfer function H TI Since active noise control depends on the magnitude of this transfer function, it is challenging to provide optimally perceived active noise control for any user every time an in-ear headphone device is worn. Active noise control also affects the inward total transfer function H TI , which can also be affected by user variations, resulting in further distortion. An adaptive filter is used, but the inward total transfer function H TI If is changing rapidly or significantly, the adaptive filter may not be able to track the changes without producing audible artifacts.

[0030] Similar variations can occur in the inverse transfer function, i.e., the outward total transfer function H TO can vary between users and each time an in-ear headphone device is worn. As a result, properly addressing loudspeaker feedback is a challenge because the efficiency with which sound from the loudspeaker reaches the microphone is unpredictable due to user variability.

[0031] Furthermore, user variation degrades the acoustic reproduction of desired audio signals in the bass frequency regime. A further problem with in-ear headphone devices is associated with dynamic acoustic leakage. These dynamic acoustic leakages can occur particularly during a user's jaw movements, which can disrupt the typically nearly airtight barrier or acoustic seal between the ear canal and the external environment. For example, while a user speaks or chews, the small air passages, also referred to as leakage, between the headphone tip and the ear canal can continuously open and close, or at least change the sound propagation characteristics of the flexible tip.

[0032] For in-ear headphone devices configured to provide active noise control, dynamic acoustic leakage is particularly problematic. First, dynamic acoustic leakage can suddenly introduce unwanted noise. Second, dynamic acoustic leakage can affect the inward total transfer function H TI This can change the magnitude associated with the outward transfer function H, which typically distorts the active noise control, since the active noise control relies on this transfer function. TO is also affected by dynamic acoustic leakage, which consequently alters any loudspeaker feedback and may result in undesired distortion of the active noise control signal. Additionally, acoustic leakage affects the inward total transfer function H TI This can strongly affect the group delay associated with the active noise control, thereby further distorting the active noise control.

[0033] Furthermore, the reproduction of a desired audio signal, e.g., music, perceived by a user may also be distorted because dynamic acoustic leakage affects the efficiency of transmission from the ear canal to the external acoustic environment and thereby from the loudspeaker to the user's eardrum.

[0034] Therefore, the problem presented in the field of in-ear headphone devices configured to provide active noise control can be summarized as follows:

[0035] - The occlusion effect cannot be suppressed without degrading the active noise control by introducing Helmholtz resonance. - The occlusion effect cannot be suppressed without degrading the sound reproduction by introducing Helmholtz resonance.

[0036] The occlusion effect cannot be suppressed without degradation of the loudspeaker reproduction of sound, especially in the bass frequency range, as it leaves the device. - User fluctuation is the inward total transfer function H TI This can affect the volume and distort the active noise control.

[0037] - User fluctuation is the inward total transfer function H TI This can affect the phase of the signal and distort the active noise control. - User fluctuations are the outward total transfer function H TO This can affect the sound quality and cause loudspeaker feedback distortion.

[0038] - User fluctuation is the outward total transfer function H TO This can affect the reproduction of desired audio signals, distorting the reproduction of desired audio signals, especially in the bass frequency range. - Dynamic acoustic leakage can suddenly introduce noise that active noise control cannot suppress.

[0039] - Dynamic acoustic leakage is the inward total transfer function H TI This can affect the volume and distort the active noise control. - Dynamic acoustic leakage is the inward total transfer function H TI This can affect the phase of the signal and distort the active noise control.

[0040] - Dynamic acoustic leakage is the total outward transfer function H TO may affect the sound quality and distort the loudspeaker feedback; and / or - Dynamic acoustic leakage is the total outward transfer function H TOThis can affect the reproduction of desired audio signals, distorting the reproduction of desired audio signals, especially in the bass frequency range.

[0041] The present inventors have devised novel and inventive solutions to the problems presented above that relate to the field of in-ear headphone devices, and in particular to in-ear headphone devices configured to provide active noise control. Comprehensive models and extensive simulations of wearable in-ear headphone devices demonstrate the feasibility of embodiments of the present invention for overcoming or reducing one or more of the described problems, preferably several of the problems simultaneously within the same device.

[0042] The in-ear headphone device according to the present invention comprises a damped vent comprising one or more vent elements and one or more damping elements. The damped vent may be, for example, a vent with a damping net located at one or both ends of the vent, or a vent configured with an integrated damping effect. According to the present invention, the damped vent is configured to couple the ear canal to the external acoustic environment.

[0043] According to one embodiment, the damped vent has an inward vent transfer function H of the damped vent within a reference frequency range of 100 Hz to 2 kHz. VI The magnitude of the resonance of the inward vent transfer function H VI In other words, the damped vent is configured to dampen resonance peaks occurring within a frequency range of 100 Hz to 2 kHz.

[0044] An undamped vent, combined with the sealed cavity of the ear canal as explained above, will typically cause a Helmholtz resonance somewhere within this frequency range when the vent is tuned for audio purposes, e.g., to reduce occlusion effects. The magnitude of such acoustic resonance is typically, e.g., 6 dB above the substantially flat magnitude at low frequencies.

[0045] A damped vent according to the present invention allows a maximum of 3 dB peaking within a typical resonant frequency band, rather than the natural, e.g., 6 dB, thereby at least halving the sound pressure level at the peak of the Helmholtz resonance. In a preferred embodiment, the damped vent is critically damped, thereby suppressing the peak to a reference level, leaving a substantially flat frequency response somewhere between 20 Hz and the cutoff frequency, e.g., 400 Hz and 2 kHz, e.g., 800 Hz or 1 kHz. In one embodiment, the damped vent may be over-damped, i.e., further suppressing the peak below the reference magnitude.

[0046] One skilled in the art of acoustics can design a damped vent based on the features provided herein by selecting an appropriate damping fabric or other damping material to provide inside the vent or on one or both ends of the vent, and / or can provide geometric features of the vent design, such as slits, designed to achieve the damping effect. Examples of vent dimensions and damping elements are also provided in connection with models for simulations described below with reference to the figures.

[0047] The damped vent aspect of the present invention is particularly inventive because coupling the ear canal to the external acoustic environment in an in-ear headphone device configured to provide noise control is highly counterintuitive. While the vent itself can passively suppress the occlusion effect, it also reduces the effectiveness of passive noise control and introduces Helmholtz resonance. However, by further including damping elements and implementing judicious selection of design parameters, it is possible to significantly improve the performance of an in-ear headphone device, contrary to the expected performance reduction.

[0048] To further present the present invention, it is useful to introduce some additional concepts. The attenuated vent has an inward vent transfer function H from the external acoustic environment to the ear canal. VI and the outward vent transfer function H from the ear canal to the external acoustic environment VO Dynamic acoustic leakage can be characterized by the inward leakage transfer function H from the external acoustic environment to the ear canal. LI and the outward leakage transfer function H from the ear canal to the external acoustic environment LO It can be characterized by:

[0049] Furthermore, if the noise microphone is configured to primarily record sounds from the external acoustic environment, the in-ear headphone device may include an electro-acoustic path comprising, for example, the noise microphone, a signal processor, and a loudspeaker, which has an inward electro-acoustic transfer function H from the external acoustic environment to the ear canal. EI It can be characterized by:

[0050] Inward total transfer function H TI is, for example, the inward vent transfer function H VI and the inward leakage transfer function H LI while the total outward transfer function H TO is the outward vent transfer function H VO and the outward leakage transfer function H LO It may have a combination of:

[0051] Below, evidence is presented that explains why attenuated vents are not a drawback for in-ear headphone devices and can actually, contrary to expectations, produce many improvements to such devices.

[0052] A concern associated with adding attenuating vents to in-ear headphone devices configured to provide active noise control may be that the attenuating vents may introduce additional noise into the user's ear canal. However, the inward vent transfer function H VI This additional noise is therefore easy for active noise control to suppress, since it can typically be well-defined and well-known.

[0053] The addition of non-damped vents to in-ear headphone devices can reduce the occlusion effect when the device is worn, but results in Helmholtz resonance. By adding additional damping elements to the vents, Helmholtz resonance and the associated distortion it can generate can be eliminated.

[0054] Therefore, the occlusion effect can be suppressed without degrading active noise control and sound reproduction due to the presence of Helmholtz resonance. Furthermore, the addition of a vent can typically degrade sound reproduction, especially in the bass frequency range, by allowing sound to leave the device. However, the damping element reduces this effect, providing improved sound reproduction, especially in the bass frequency range, compared to a device without the damping element.

[0055] By implementing a damped vent, some of the issues related to user variability may also be addressed. Active noise control can typically be configured to suppress audible frequencies up to frequencies on the order of 1 kHz. At these frequencies, user variation can affect the total inward transfer function H for both in-ear headphone devices without vents and devices with unattenuated vents. TI The total inward transfer function H for a device with damped vents can be significantly affected. TI The effect of user variations on σ is greatly reduced at the relevant frequencies.

[0056] Similarly, the total outward transfer function H TO is less affected by user variation in in-ear headphone devices with attenuated vents, and loudspeaker feedback may therefore produce less distortion. TO It also affects the reproduction of desired audio signals in the ear canal, especially in the bass frequency range, and the attenuated vent improves sound reproduction in this frequency range.

[0057] Attenuated vents are particularly efficient in solving problems associated with dynamic leakage. In a typical in-ear headphone device without attenuated vents, any sound that suddenly enters the ear canal through generated dynamic acoustic leakage can be heard very noticeably by the user. In contrast, in an exemplary embodiment of the present invention, noise can enter through both the attenuated vents and the dynamic acoustic leakage. Attenuated vents have a predictable inward vent transfer function H VI Since the dynamic sound leakage filter has a damping coefficient of 0.01, noise that enters through the attenuation vent is easily suppressed. Importantly, any sound that enters the ear canal due to dynamic sound leakage can exit again through the attenuation vent. Therefore, according to embodiments of the present invention, the sound of dynamic sound leakage is heard by the user at a much lower volume than sound that cannot exit through the vent and leaks into the ear canal.

[0058] For in-ear headphone devices with ventless active noise control, the dynamic acoustic leakage is the inward total transfer function H, since the leakage transfer function is the dominant part of the total transfer function in this case. TI This can strongly change the inward total transfer function H TI As a result, the dynamic acoustic leakage is related to both the magnitude and phase of the inward total transfer function H TI may be continuously varied to produce distortions of the active noise control and consequently audible artifacts. In an exemplary embodiment according to the present invention, the damped vent is configured with an inward vent transfer function H VI is the inward total transfer function H TI , the inward total transfer function H TI remains almost unchanged, resulting in a significantly reduced amount of variation, thereby ensuring a reduction in audible artifacts due to adaptation mismatch.

[0059] Similarly, the total outward transfer function H TO is less affected by dynamic acoustic leakage in in-ear headphone devices with damped vents, and loudspeaker feedback may therefore produce even less distortion. TO Additionally, the attenuated vent also affects the reproduction of desired audio signals in the ear canal, especially in the bass frequency range, and the attenuated vent improves sound reproduction in this frequency range.

[0060] To summarize the presented advantages and solutions, the inventors have identified and solved numerous problems in the field of in-ear headphone devices configured to provide active noise control in accordance with the present invention. The solution to these problems is generally based on the inventiveness of novel damped vents, which are carefully crafted to eliminate undesirable resonance effects, such as Helmholtz resonance, while also allowing substantial acoustic coupling between the ear canal and the surrounding environment. As a result, in-ear headphone devices according to embodiments of the present invention: - The occlusion effect can be suppressed without degrading the active noise control by introducing time-varying Helmholtz resonance. - The occlusion effect can be suppressed without degrading the sound reproduction by introducing time-varying Helmholtz resonance, - Suppresses occlusion effects while minimizing degradation of loudspeaker reproduction due to sounds leaving the device, especially in the bass frequency range; - User fluctuation is the inward total transfer function H TI It can reduce distortion caused by affecting the size of - User fluctuation is the inward total transfer function H TI This reduces distortion caused by affecting the phase of the - User fluctuation is the outward total transfer function H TO It can reduce distortion from loudspeaker feedback by affecting - Total outward transfer function H TO The reduced effect of user variation on the loudspeaker-to-eardrum transfer function, associated with - The effect of sound entering the ear canal via dynamic acoustic leakage can be reduced by allowing dynamic acoustic leakage to exit through the attenuated vent; - Dynamic acoustic leakage is the inward total transfer function H TI It can reduce distortion caused by affecting the size of - Dynamic acoustic leakage is the inward total transfer function H TI This reduces distortion caused by affecting the phase of the - Dynamic acoustic leakage is the total outward transfer function H TO can reduce distortion from loudspeaker feedback by affecting - Total outward transfer function H TO The reduced effect of dynamic acoustic leakage on the loudspeaker-to-eardrum transfer function associated with the eigenvalue (E) can improve loudspeaker reproduction, especially of sounds in the bass frequency range.

[0061] Compared to both closed designs and designs with unattenuated vents, active noise control filters in embodiments of the present invention with attenuated vents configured to model the inward and outward transfer functions may have smoother amplitude and phase characteristics and may change less when algorithms such as LMS are used to adapt to changes in leakage or ear canal positioning.

[0062] Compared to acoustic designs in which the loudspeaker and vent share a common volume before reaching the ear canal, this disclosed configuration has the advantage that less sound is transmitted from the loudspeaker to the external-facing microphone, especially at frequencies above the vent cutoff.

[0063] In one embodiment, the inward vent transfer function H VI and the acoustic resonance is characteristic of the attenuated vent when the in-ear headphone device is inserted into the person's ear canal.

[0064] The acoustic characteristics of in-ear headphone devices vary depending on the environment in which they are evaluated. In this disclosure, the acoustic characteristics are considered for an inserted device, i.e., with one end of the loudspeaker and damping vent coupled to a closed ear canal cavity and the other end of the damping vent open to the external acoustic environment, specifically the concha. Acoustic resonances are thereby considered as a result of interactions between, for example, a tube coupling the closed cavity to open space.

[0065] In one embodiment, the loudspeaker and the attenuated vent are acoustically isolated inside the in-ear headphone device. In some embodiments, the loudspeaker and the attenuated vent preferably do not directly overlap a common chamber or duct or the like, thereby not having a common exit from the headphone device to the ear canal.

[0066] In one embodiment, the loudspeaker and the attenuated vent are acoustically separated by a damping element inside the in-ear headphone device. In some embodiments, the loudspeaker and the damped vent are acoustically separated or partitioned by a damping element.

[0067] In one embodiment, the loudspeaker and the attenuated vent are coupled to the ear canal by separate ducts. This allows the loudspeaker sound to be delivered primarily to the ear canal, compared to embodiments where the loudspeaker and vent are combined inside the device by a common duct to the ear canal, with more sound passing through the vent to the external environment without reaching the eardrum.

[0068] In one embodiment, the attenuated vent is configured with a cross-sectional area equivalent to a cylinder having a diameter in the range of 1.5 mm to 3.5 mm, such as 2.0 mm to 3.0 mm, for example 2.3 mm or 2.5 mm.

[0069] A preferred cross-sectional area of ​​the attenuated vent is, for example, 1.8 mm 2 to 9.6 mm 2 , for example 3.1mm 2 to 7.1 mm 2 Within the range of, for example, 4.2 mm 2 or 4.9mm 2 The attenuated vent may have a variety of cross-sectional shapes, such as circular, rectangular, semicircular, etc., may have a cross-sectional area that varies along its length, or may be combined with two or more vents, split vents, etc., but is preferably designed with dimensions equivalent to the above-mentioned dimensions of a cylindrical vent.

[0070] In one embodiment, the attenuated vent is configured with a length equivalent to a cylinder having a length in the range of 2.5mm to 10mm, such as 3.5mm to 9mm, 4.5mm to 8mm, etc., for example 5mm or 7mm.

[0071] The attenuated vent may have a variety of shapes along its length, such as being straight, curved, or bent, and may be combined with two or more vents, split vents, etc., but is preferably designed with dimensions equal to the above-mentioned dimensions of a cylindrical vent.

[0072] In one embodiment, the vent may be characterized by an acoustic mass based on the cross-sectional area and the length of the attenuated vent, and the combination of the acoustic mass and the typical effective volume of the ear canal may be characterized by a vent cutoff frequency selected from within a range of 500 Hz to 2000 Hz, such as 650 Hz to 1600 Hz, 700 Hz to 1200 Hz, etc., e.g., 800 Hz, 900 Hz, or 1000 Hz.

[0073] Acoustic mass may also be understood as acoustic inertia, describing the reluctance of a body of air to change its velocity. For example, in one embodiment of the present invention, the body of air within a damped vent may have an acoustic mass determined by the length and cross-sectional area of ​​the damped vent. The acoustic mass combined with the typical effective volume of the ear canal may be characterized by the vent cutoff frequency. The typical effective volume of the ear canal may be understood, for example, as the remaining volume of the ear canal when the device is inserted into the ear canal of an average or typical user.

[0074] In one embodiment, the noise microphone is configured to primarily record sounds from the external acoustic environment. An advantage of recording sounds for acoustic noise control from the external acoustic environment is that noise can be measured with minimal influence from sounds present in the ear canal, which may include desired sounds reproduced by the headphone device, such as music playback or telephone conversations. Feedback from the internal loudspeaker to the externally directed microphone can be measured and considered in this process. Furthermore, the externally directed noise microphone can advantageously be used for a dual purpose, recording both the noise to be canceled and desired environmental sounds that should not be canceled but should be enhanced, such as voice conversations, notifications, or desired warning sounds. Some degree of directionality, for example for voice conversations, can be achieved by appropriately positioning the microphone or by using several microphones or microphone ports in different locations on the headphone device. The differentiation between sounds to be canceled and sounds to not be canceled and possibly even enhanced can be based on simple crossover filters, for example with a crossover frequency at about 800-1000 Hz, or on more advanced algorithms, such as signal component differentiation techniques that detect and maintain or enhance vocal features within the recorded sound and create an active noise control signal based on the remainder of the recorded signal. Dual-purpose noise microphones may also be used to record the user's own voice, for example for telecommunications or digital assistance purposes.

[0075] In one embodiment, the noise microphone is configured to primarily record sounds from the ear canal. By using sound in the ear canal as input to the active noise control, i.e., by recording it with a noise microphone aimed at the ear canal, the active noise control algorithm receives direct feedback on the performance of the active noise control signal actually reproduced in the ear canal. This can result in faster and / or more accurate adjustments to the active noise control signal. Desired sounds reproduced by the headphone device itself, such as music playback or telephone conversations, can be subtracted from the feedback signal before applying it as an error signal to the active noise control algorithm. Additionally, desired environmental sounds, such as voice conversations and notifications, can be preserved to some extent by using crossover filters or other signal component differentiation techniques, such as voice feature extraction.

[0076] In one embodiment, the in-ear headphone device includes an auxiliary microphone. Various embodiments can utilize several microphones for various purposes. An auxiliary microphone located opposite the noise microphone, i.e., directed toward the ear canal when the noise microphone is configured to primarily record environmental sounds, or directed toward the environment when the noise microphone is configured to primarily record ear canal sounds, can assist the signal processor during tasks for which the noise microphone is less advantageous. For example, an auxiliary microphone directed toward the ear canal can provide an error signal to an active noise control algorithm based on a noise microphone directed toward the environment, and vice versa. Additionally, an auxiliary microphone can be used to record a user's voice for telecommunications and digital assistance purposes. The combination of a noise microphone and an auxiliary microphone can further be used to measure the transfer function from the environment to the ear canal, or vice versa. Furthermore, several environmentally directed microphones located at different locations around the headphone device can improve the directionality of sound recording, for example, for improved differentiation between desired conversational voices and background noise.

[0077] In one embodiment, a microphone configured to primarily record sound from the ear canal is coupled to the ear canal via a separate microphone duct. A microphone directed toward the ear canal, whether a noise microphone or an auxiliary microphone, may preferably be coupled to the ear canal via a separate microphone duct, so that the microphone occupies less space in the ear canal and is not directly coupled to a loudspeaker or a damped vent chamber or duct. By using a microphone duct, the microphone receives the mix of sounds present in the ear canal, as affected only by the predictable transfer function of the microphone duct.

[0078] In one embodiment, a microphone is acoustically coupled to the ear canal through the attenuated vent. In some embodiments of the present invention, a microphone, e.g., a noise microphone, can record sound directly from the attenuated vent. Depending on the placement of one or more attenuation elements, the microphone can therefore record primarily sound from the external environment, sound from the ear canal, or a balanced mix of sound from the external environment and sound from the ear canal.

[0079] In one embodiment, the signal processor is operable to estimate the inward total transfer function H TI and providing the active noise control signal based on the Essentially, the active noise control algorithm calculates the opposite side of the noise that remains after it propagates from the environment to the ear canal through attenuated vents, dynamic acoustic leakage, and electro-acoustic paths, if any, i.e., the inward total transfer function H TI Therefore, it is advantageous, especially for noise microphones facing the environment, to base the active noise control signal on an estimate of this transfer function. TI may be estimated at design or manufacturing time, stored as a predetermined function within the headphone device, and used as a starting point. However, the headphone device is preferably configured to update the transfer function to adapt to variable dynamic acoustic leakage, variable characteristics of the user's ear canal, etc. During use, the inward total transfer function H TI Some of the possibilities for estimating, i.e. adapting, are described above.

[0080] In one embodiment, the estimated inward total transfer function H TI is the inward vent transfer function H VI Based on estimates. As explained above, the inward vent transfer function H VI is the total inward transfer function H TI forms a major and fairly predictable part of the inward vent transfer function H VIcan be estimated based on a model of a substantially fixed damped vent or measurements by the designer or manufacturer, so that the total inward transfer function H TI A good estimate of is, if possible, the inward leakage transfer function H LI The inward vent transfer function H, taking into account an averaged or estimated model for VI can be based on an estimate of

[0081] In one embodiment, the estimated inward total transfer function H TI is based on the difference in the sound recordings of the external acoustic environment and the ear canal, respectively. If microphones are available for both primarily environmental sounds and primarily ear canal sounds, for example by configuring a noise microphone facing the environment and an auxiliary error microphone facing the ear canal, or by configuring a noise microphone facing the ear canal and an auxiliary microphone for telecommunications, digital assistance, and / or speech enhancement facing the environment, a comparison of the sounds they record can be made using the inward total transfer function H TI can be used to determine an estimate of

[0082] In one embodiment, the estimated inward total transfer function H TI is the estimated outward total transfer function H TO Based on. Outward total transfer function H TO If is known or estimated, this results in an inward total transfer function H whose poles and zeros can be transformed and used to improve active noise control. TI , i.e., an estimate in the opposite direction can be found.

[0083] In one embodiment, the estimated outward total transfer function H TO is based on the difference between the sound reproduced by the loudspeaker and the sound recorded by the noise microphone.

[0084] If a noise microphone or auxiliary microphone is positioned to primarily record noise from the external environment, it will also record sound feedback from the loudspeakers that typically escapes through vents, leaks, and headphones. By comparing the loudspeaker outputs with the outer microphone inputs, the outward total transfer function H TO An estimate of the outward total transfer function H can be determined. This is advantageous in itself, since it allows the signal processor to control undesired feedback from the loudspeaker to the microphone, avoiding, in the worst case, e.g., buzzing or squealing. Furthermore, the measured or estimated outward total transfer function H TO is the total inward transfer function H to improve the active noise control as explained above. TI Therefore, the total outward transfer function H TO Estimation or measurement of can be used in active noise control as well as in active feedback control.

[0085] In one embodiment, the signal processor is configured with an active noise control algorithm for providing the active noise control signal, the active noise control algorithm being of the LMS algorithm type, for example a filtered-x LMS or a direction search LMS, and characterized by a step size.

[0086] A variety of suitable active noise control algorithms are available to those skilled in the art of headphone devices with active noise control. Essentially, an active noise control algorithm comprises an adaptive filter that is continuously updated to produce a sound that is as opposite as possible to the undesired noise. Because active noise control typically does not apply to higher frequencies, a typical sample rate of the recorded noise signal may be, for example, 2 kHz, thereby enabling active noise control for noise below 1 kHz. Other frequency ranges for active noise control are available to those skilled in the art by appropriately adjusting other frequency ranges, for example by tuning the characteristic frequency of the damped vent.

[0087] A relevant parameter of the different active noise control algorithms is the step size, which determines how much the adaptive filter is changed with each algorithm iteration. A smaller step size allows for more accurate adaptation to the measured noise, while a larger step size allows for keeping track of large and fast changes in the unwanted noise. If the step size chosen is too small for the purpose of increasing accuracy, leakage will increase the overall inward transfer function H TIAdaptive noise filters in headphones without attenuated vents, the largest part of the noise filter, cannot track large changes in noise characteristics due to fluctuations in dynamic acoustic leakage, such as when a user chews or speaks. This can result in audible artifacts whenever the noise characteristics or transfer function are significantly altered. On the other hand, if the step size selected with the goal of quickly adapting to large changes in the transfer function is too large, the adaptive filter tends to exceed each correction value and oscillate around the optimal filter setting. This can result in audible artifacts or reduced noise suppression during the stabilization state, when the noise and transfer function simply change smoothly over time. In some active noise control algorithms, it may be possible to increase the frequency of algorithm iterations to allow the use of smaller step sizes while still finding the optimal filter setting as quickly as with larger step sizes. In one example, doubling the processing frequency may allow the step size to be halved without reducing the algorithm's response to large changes. However, increasing the processing frequency requires more expensive processors and ancillary components and consumes more battery power. In other words, there is some trade-off between filter adaptation performance, processing speed, cost, and battery consumption.

[0088] According to an embodiment of the present invention, the inward total transfer function H TI The stability of is due in large part to the unpredictable and dynamic inward leakage transfer function H LI The inward vent transfer function H is substantially fixed and somewhat predictable over time compared to vI It can be improved by relying on a more stable inward total transfer function H TIAs a result, the degree of adaptation required by the active noise control algorithm and adaptive filter is reduced compared to headphones without damped vents. This benefit can be used for a variety of purposes with different interests. An advantageous embodiment utilizes the improved transfer function stability to reduce the step size, thereby achieving more accurate noise control during stable states without reducing tracking performance in dynamic states, since dynamic states are less dynamic due to the stable transfer function provided by the damped vents. Another advantageous embodiment utilizes the improved transfer function stability to reduce processing requirements, e.g., using cheaper components and / or a slower processing frequency, again without reducing tracking performance in dynamic states, since dynamic states are less dynamic due to the stable transfer function provided by the damped vents. Other combinations of the above-mentioned tradeoff parameters are also appropriate and are advantageous embodiments of the present invention.

[0089] Generally, active noise control can be causal or non-causal. In causal active noise control, a microphone is typically located closer to the noise source than the loudspeaker, so that sound wave segments recorded at the noise microphone can be processed in time for the loudspeaker to play an active noise control signal configured to cancel the recorded sound wave segments in the ear canal.

[0090] In acausal active noise control, sound wave segments recorded at a noise microphone do not have to be processed in time to cancel the same sound wave segments in the ear canal. Instead, acausal active noise control relies on recorded sounds to predict future noise in the ear canal. Even in embodiments where causal active noise control is possible, the active noise control can benefit in some embodiments from including a component of future noise prediction, i.e., a prediction of how received sounds will unfold, in order to pre-adjust the algorithm in the right direction.

[0091] In embodiments in which the noise microphone is configured to record sounds primarily from the ear canal, the active noise control may typically be acausal active noise control. Thus, active occlusion control may typically be a type of acausal active noise control.

[0092] Acausal and causal active noise control require different signal processing procedures. Signal processing for acausal active noise control typically relies to a greater extent on prediction, since it relies on predicting future noise.

[0093] Embodiments of the present invention are typically characterized by better predictability than devices without attenuated vents. For example, the omnidirectional inward transfer function is less susceptible to dynamic acoustic leakage. Therefore, embodiments of the present invention may also provide improved non-causal active noise control, or a combination of causal and non-causal active noise control.

[0094] In one embodiment, the in-ear headphone device is configured with a crossover frequency, voice extraction function, or other means of separation between sounds desired to be subjected to active noise control and sounds desired to be heard unaffected or enhanced.

[0095] For some applications of in-ear headphone devices, active noise control, or the complete use of active noise control, may not be desired. This may be, for example, an embodiment where a user may sometimes desire to hear environmental sounds, such as conversations, notifications, traffic directions, etc. The use of an appropriate crossover frequency, for example, at about 800 Hz to 1 kHz, or a voice extraction function or other separation means, may allow for different treatment of sounds such as noises for which active noise control is desired and sounds such as voices that are desired to be heard unaffected or enhanced. The separation means may advantageously be user-configurable and / or can be switched on or off as needed.

[0096] In one embodiment, the in-ear headphone device is configured with options to switch the active noise control signal on or off and adjust the frequency range or mode of the noise being controlled.

[0097] In some embodiments, it may be desirable to provide user-selectable active noise control, allowing the user to turn it off when it is not relevant or even desired, for example in some of the situations mentioned above. In one embodiment, the settings of the active noise control algorithm may be user-configurable directly or indirectly by allowing the user to select the frequency range of the noise control, the degree of noise suppression, choose between large or small step sizes for fast tracking or precise and stable conditions, etc., or by allowing the user to select the noise control mode, for example, the need for quiet or noisy environments, steady or dynamic use, whether to listen to the environment while controlling the noise, or whether to desire as much sound suppression as possible, etc.

[0098] In one embodiment, the estimated inward total transfer function H TI is the inward leakage transfer function H LI and a time-varying inward transfer function component comprising the inward vent transfer function H VI and a static inward transfer function component comprising:

[0099] As explained above, the inward total transfer function H for a headphone device with both damped vents and unavoidable dynamic acoustic leakage is TI includes at least a preferably major, substantially stable, and predictable contribution from the damped vent and a preferably small, time-varying, and unstable contribution from dynamic acoustic leakage. Thus, advantageous embodiments provide an estimated inward total transfer function H TI In some embodiments, these components are measured, estimated, or modeled separately, thereby forming the inward total transfer function H TI In another embodiment, the inward total transfer function H TIis measured, estimated, or modeled in a manner that does not allow for the distinction of the two components, but comprises these two components, but not separately.

[0100] In one embodiment, the signal processor is operable to process the estimated inward total transfer function H TI at an active noise control sample rate or algorithm iteration rate, e.g., in the range of 800 to 4000 times per second, e.g., 1200 to 3000 times per second, e.g., 2000 times per second.

[0101] The inward total transfer function H as recognized by those skilled in the art TI The adaptive active noise control filter representing is preferably continuously updated to track smooth and frequent changes in the noise characteristic or transfer function. However, compared to headphone devices without damped vents, the step size of the algorithm, e.g., the step size of an LMS algorithm, may be reduced in embodiments of the present invention without increasing the algorithm iteration rate or otherwise increasing processing requirements.

[0102] In one embodiment, the signal processor is adapted to multiply the estimated inward total transfer function H TI is configured to update said representation of

[0103] The adaptive active noise control filter is preferably updated as described above in steps determined by a predetermined, but configurable, step size selected to achieve a good compromise between accurate tracking of the noise characteristics and transfer function and fast tracking, where audible artifacts are reduced as much as possible. However, compared to headphone devices without attenuated vents, the step size of the algorithm, e.g., the step size of the LMS algorithm, can be reduced in embodiments of the present invention without increasing tracking time or audible artifacts.

[0104] In one embodiment, the signal processor is configured to provide an active occlusion control signal and the loudspeaker is configured to reproduce the active occlusion control signal in the ear canal.

[0105] In one embodiment, the active occlusion control signal is based on a signal recorded from a microphone configured to primarily record sounds from the ear canal, such as a noise microphone configured to primarily record sounds from the ear canal.

[0106] Embodiments of the present invention are preferentially configured to suppress the occlusion effect, but may not completely eliminate it. Accordingly, some embodiments of the present invention are configured to provide active occlusion control, where a microphone is typically capable of recording sounds, e.g., occlusion, from the ear canal, and based on this recording, a processor can generate an active occlusion control signal, which a loudspeaker can play in the ear canal to further suppress the occlusion effect.

[0107] The overall procedure for active occlusion control is similar to that for active noise control, especially when the noise microphone is configured to record sounds primarily from the ear canal. In some embodiments of the present invention, the active noise control signal may also be interpreted as an active occlusion control signal.

[0108] In embodiments in which the noise microphone is configured to primarily record sound from the ear canal, the active noise control may typically be acausal active noise control. Active occlusion control may therefore typically be a type of acausal active noise control, which may require greater predictability because it relies on prediction of future noise. Embodiments of the present invention having attenuated vents are typically characterized by better predictability than devices without attenuated vents, such that the total inward transfer function is less susceptible to dynamic acoustic leakage. Thus, embodiments of the present invention may also provide improved acausal active noise control, such as improved active occlusion control.

[0109] In one embodiment, the magnitude of the resonance is determined by the inward vent transfer function H VI It can be any size. The damped vents of the present invention are preferably configured to not allow amplitudes greater than 3 dB above the reference amplitude in the 100 Hz to 2 kHz band, regardless of the source of the amplitude. In other words, amplitude peaks that appear in an undamped vent in the above-referenced frequency ranges are within the scope of the present invention, whether they are caused directly, indirectly, or not by resonance phenomena. In a preferred embodiment, a damped vent is provided, where the inward vent transfer function H VIis substantially flat, i.e., has no peaks greater than 3 dB across the reference magnitude, preferably over the entire range of 20 Hz to 2 kHz, but at least from 100 Hz to 2 kHz. The reference magnitude of the transfer function is typically 0 dB. In some embodiments, the attenuation element is further configured to provide a nominal attenuation of the reference band within a range of, e.g., 2 dB to 10 dB, e.g., 2 dB to 6 dB, e.g., 3 dB to 4 dB. In such embodiments, the attenuated vent is configured to not allow the magnitude within the frequency range of 100 Hz to 2 kHz to exceed 3 dB above the nominal attenuation.

[0110] In one embodiment, the magnitude of the resonance is determined by the inward vent transfer function H at 800 Hz. VI It is the size of. A damped vent that achieves damping of the resonance at 800 Hz to reduce the magnitude of the resonance to no more than 3 dB below the reference magnitude between 20 Hz and 100 Hz is highly advantageous since the frequency range around 800 Hz is particularly relevant for headphone and active noise control applications.

[0111] In one embodiment, the magnitude of the resonance is at most 2 dB, such as at most 1 dB, for example at most 0 dB, greater than the magnitude of the reference. In a preferred embodiment, the magnitude of the resonance is reduced as close to 0 dB as possible relative to the nominal magnitude. In one embodiment, the damped vent may be further over-damped, i.e., further suppressing the peak below the nominal magnitude.

[0112] In one embodiment, the reference magnitude is the magnitude of the inward vent transfer function H in the range of 20 Hz to 100 Hz, such as 20 Hz to 60 Hz or 60 Hz to 100 Hz. VI Based on the average size of

[0113] Inward vent transfer function H VIThe frequency response of is typically substantially flat within these frequency ranges, with an average magnitude typically around 0 dB. In some embodiments, the attenuation element is further configured to provide a nominal attenuation of the reference band within a range of, e.g., 2 dB to 10 dB, e.g., 2 dB to 6 dB, e.g., 3 dB to 4 dB. In such embodiments, the attenuated vent is configured to not allow the magnitude within the frequency range of 100 Hz to 2 kHz to exceed 3 dB above the nominal attenuation.

[0114] In one embodiment, the attenuation element is configured to provide a nominal attenuation in the range of 2 dB to 10 dB, such as 2 dB to 6 dB, for example 3 dB to 4 dB, in a frequency band of 50 Hz to 500 Hz, for example 500 Hz.

[0115] The nominal attenuation is preferably a broadband attenuation, reducing the reference magnitude by, for example, 3-4 dB. In such embodiments, the attenuated vent is preferably configured to attenuate the magnitude of acoustic resonances by no more than 3 dB above the reference magnitude of the nominal attenuation. For example, in one embodiment, the attenuated vent nominally attenuates all audible frequencies by about 3-4 dB, but further attenuates resonance peaks that would otherwise be 6 dB above the reference by at least an additional 3 dB, thus achieving a generally flat response within the passband, for example, between −3 dB and −4 dB, with resonance peaks attenuated no more than 0 dB, and more preferably to a critically damped state.

[0116] According to an embodiment of the present invention, the resulting sound pressure level (SPL) in the ear canal is optimized to increase speech intelligibility. When speech is presented at a very low level, important speech cues are inaudible, making phonemes difficult to distinguish and therefore difficult to understand. As the level increases, speech recognition increases, but at some point, recognition begins to decrease with increasing level. This phenomenon is often referred to as the "rollover" effect. In situations such as cocktail parties, the overall ambient SPL is often above the rollover point. According to one embodiment, an acoustically attenuating vent applies a nominal attenuation, thereby increasing speech intelligibility in loud or noisy environments.

[0117] An advantageous feature of embodiments of the present invention is passive bass processing, whereby frequencies below a low-pass cutoff frequency are acoustically attenuated. Many conventional noise suppression algorithms (including adaptive microphone directional patterns) exhibit large gains in SNR. However, these algorithms often fail to deliver better speech recognition scores in actual tests because they tend to produce "abnormal" or unnatural sounds that attract the user's attention, thereby reducing or even masking the speech to be recognized. This is circumvented by the inclusion of nominal attenuation in the present embodiment.

[0118] Embodiments of the present invention can be advantageous by facilitating longer stays in noisy or otherwise loud environments by applying a small overall or nominal attenuation. For example, a 3 dB overall attenuation can reduce noise exposure by 50%, or alternatively, allow a wearer to stay twice as long as they would without the system if their ears were subjected to the same noise exposure.

[0119] To further increase protection against exposure to loud sounds, embodiments may advantageously include means for limiting the peak SPL delivered to the ear canal. This may be done acoustically within the attenuated vent, for example by a narrow slot in the vent.

[0120] In one embodiment, the inward vent transfer function H in the range of 20 Hz to 10 kHz VI is characterized by having a low-pass characteristic, and the inward vent transfer function H is VI The magnitude of any of the above is at least 3 dB lower than the reference magnitude.

[0121] The cutoff frequency is usually defined as the frequency at which the magnitude drops 3 dB below the passband magnitude, referred to here as the reference magnitude. The attenuated vent is characterized by a low-pass characteristic from the environment to the ear canal, i.e., the inward vent transfer function H VI By designing with a filter, the bandwidth of the damped vent characteristic described above is limited to frequencies below the cutoff frequency. An advantage of a limited damped vent bandwidth may be, for example, that feedback from the internal loudspeaker to the external microphone is attenuated at frequencies above the cutoff frequency. To this end, the cutoff frequency may advantageously be selected as a compromise between allowing the most dominant noise, i.e., low frequencies, to escape the ear canal through the vent while attenuating the exit of speech frequencies important for improved speech intelligibility and feedback reduction. Another advantage may be matching the active noise control algorithm bandwidth with the low-pass characteristic of the damped vent, since the active noise control algorithm in the preferred embodiment is most efficient or possibly only applied at lower frequencies, e.g., up to 1 kHz.

[0122] Furthermore, for users with noise-induced hearing loss, which is often most noticeable around 3 kHz due to resonances in the open ear canal, it is therefore particularly advantageous to include a gain reduction mechanism that limits the power delivered to the ear around 3 kHz.

[0123] Additionally, for embodiments implementing an electroacoustic path with a high-pass characteristic as described below, the low-pass characteristic of the attenuated vent reduces acoustic masking of high frequency bands, thereby improving the degree of control and possible SNR achievable by the electroacoustic path. In one embodiment, the low-pass cutoff frequency and the high-pass cutoff frequency establish a crossover frequency between the attenuated vent and the electroacoustic path.

[0124] Furthermore, when the electroacoustic path is implemented with any type of directional microphone assembly, i.e., one or more directional microphones, or a microphone mounted in a location that effectively functions like a directional microphone, such directionality is particularly important for speech intelligibility. By implementing a limited bandwidth of the attenuated vent passband, e.g., up to 800 Hz or 1 kHz, the amount of omnidirectional sound admitted through the attenuated vent is reduced, thereby minimizing masking of directional sound received through the microphone. This can be highly advantageous because the electroacoustic path cannot attenuate the acoustically omnidirectional sound received by the attenuated vent, but it is more or less under the complete control of the gain and filters of the electroacoustic path. Directivity is particularly important for the intelligibility of consonants, i.e., consonants at the higher end of the speech frequency spectrum, thereby above a preferred cutoff frequency.

[0125] In one embodiment, the low pass cut-off frequency is in the range of 400 Hz to 2000 Hz, such as 500 Hz to 1600 Hz, such as 600 Hz to 1200 Hz, such as 800 Hz.

[0126] In one embodiment, the device further comprises an electro-acoustic path comprising a microphone that primarily records environmental sounds, e.g., the noise microphone, a variable gain, and the loudspeaker, the electro-acoustic path being configured to couple the external acoustic environment to the ear canal.

[0127] Using an electroacoustic path from the environment to the ear canal, environmental sounds can be electronically, e.g., digitally, processed and reproduced within the ear canal. In one embodiment, the variable gain is an analog filter, and a digital side chain has a gain controller implemented to control the analog filter. In another embodiment, the variable gain is also digital. The processing can have various purposes, with different advantages in different embodiments, such as amplifying certain frequency bands and attenuating others, or filtering certain sound features and attenuating others to provide a sound in the ear canal that focuses on certain sound components, e.g., speech, e.g., to improve speech intelligibility. Furthermore, according to one embodiment, the electroacoustic path can also apply a negative gain to increase speech intelligibility. The electroacoustic path can also implement peak limiting, e.g., electromechanically, by using thin membranes with limited movement within the loudspeaker and microphone, reducing the electrical gain when loud sounds are detected, and / or emitting a phase-inverted replica of the sound to be attenuated via the loudspeaker.

[0128] In one embodiment, the electroacoustic path has an inward electrical transfer function H having a high-pass characteristic with a high-pass cut-off frequency, preferably in the range of 400 Hz to 2000 Hz, 500 Hz to 1600 Hz, 600 Hz to 1200 Hz, such as 800 Hz, based on the low-pass cut-off frequency. EI It is characterized by:

[0129] The high-pass characteristic of the electro-acoustic path is preferably essentially flat from a cut-off frequency to at least 5 kHz, such as 7 kHz, In one embodiment, the low-pass cut-off frequency and the high-pass cut-off frequency establish a cross-over frequency between the attenuated vent and the electro-acoustic path.

[0130] An embodiment having both types of paths, i.e., acoustically attenuated vent and electro-acoustic path, facilitates the establishment of a hybrid transfer function by combining the transfer function of the electro-acoustic path and the transfer function of the attenuated vent. An advantageous effect of the combined transfer function is that the system's control algorithm can focus only on controlling frequencies above the crossover frequency.

[0131] In one embodiment, the electro-acoustic path is configured to apply a high-pass gain to frequencies above the high-pass cutoff frequency, preferably in the range of -30 dB to 20 dB at 3 kHz, such as in the range of -25 dB to 15 dB at 3 kHz, or in the range of -20 dB to 10 dB at 3 kHz.

[0132] In one embodiment, said configuring said damped vent to damp said acoustic resonance is obtained by using said damping element. In other words, preferably the damping element of the damped vent causes the acoustic resonance to be damped, reducing the magnitude of the resonance so that it does not exceed the reference magnitude by more than a few dB as explained above.

[0133] In one embodiment, said one or more vent elements comprise one or more of said one or more damping elements. In some embodiments of the present invention, any one or more damping elements may be constructed within one or more vent elements.

[0134] In one embodiment, the one or more damping elements comprise a damping fabric, a damping net, a damping foam and / or a damping slit. The damping element can have any shape or material as long as it can oppose acoustic flow to some degree. A damping element can be characterized by an acoustic impedance, which measures the opposing force the damping element exerts on acoustic flow. Thus, a damping element and its acoustic impedance are analogous to a resistor and its resistance in an electric circuit.

[0135] In one embodiment, the one or more damping elements are characterized by an acoustic impedance, the acoustic impedance being in the range of 20 acoustic ohms to 500 acoustic ohms, such as 50 acoustic ohms to 400 acoustic ohms, for example 180 acoustic ohms or 200 acoustic ohms.

[0136] The acoustic ohm is in CGS units, i.e. 1 acoustic ohm = 1 dyne·s / cm 5 where the dyne is the derived unit of force in the CGS system. In one embodiment, the in-ear headphone device is battery powered, for example by a rechargeable battery.

[0137] In one embodiment, the in-ear headphone device is configured to accept an external audio signal, for example through an audio signal interface, and the loudspeaker is configured to play the external audio signal.

[0138] In many embodiments, it may be desirable to enable an external audio signal, which may be emitted as sound by a loudspeaker, to be provided to the in-ear headphone device. The external audio signal may be provided from an external unit, such as an audio source, configured to output an electrical audio signal and equipped with connection means for sending the audio signal to the in-ear headphone device. Examples of connection means are a wired connection, such as a cabled connection, and a wireless connection, such as a Bluetooth® connection, e.g., Bluetooth A2DP or Bluetooth aptX, or a Wi-Fi® connection.

[0139] In some embodiments, the external audio signal may be processed before being played by the loudspeakers. In one embodiment, the in-ear headphone device is configured as a true wireless headphone.

[0140] Therefore, the in-ear headphones do not require a cable to connect to an audio source or to connect two in-ear headphones of a set. In one embodiment, the in-ear headphone device is configured to transmit a signal recorded by a microphone, for example the noise microphone or the auxiliary microphone.

[0141] In some embodiments of the invention, it may be advantageous for a microphone to record sounds that can then be transmitted, for example for telecommunication purposes. This recording may preferably be performed by a microphone configured to primarily record sounds from the external environment.

[0142] The present invention further relates to an in-ear headphone device set comprising a first in-ear headphone device and a second in-ear headphone device according to any of the above, the first in-ear headphone device being configured to be fitted to a first outer ear of a user and the second in-ear headphone device being configured to be fitted to a second outer ear of the user.

[0143] Many embodiments of the present invention comprise a set of two in-ear headphone devices, which may be worn by a user, for example, over the left and right outer ears, respectively, and the housings of the two devices in the set may therefore typically be mirror images.

[0144] This ensures noise control for both ears of the user, and also allows the user to hear the desired audio signal in stereo. In an embodiment of the present invention, the first in-ear headphone device and the second in-ear headphone device may have different processes, for example, one of the devices may be a master device and the other device is a slave device, with the master device controlling the slave device and acting as a communication hub.

[0145] In an embodiment of the present invention, two in-ear headphone devices are configured to communicate with each other directly or indirectly, for example via a common controller, in order to coordinate settings or to provide improved directional sound processing or active noise control.

[0146] Various embodiments and advantages of the present invention are described below with reference to the figures. [Brief explanation of the drawings]

[0147] [Figure 1] 1 illustrates an in-ear headphone device according to an embodiment of the present invention. [Figure 2] FIG. 10 illustrates an exemplary inward vent transfer function in accordance with the present invention. [Figure 3a] 1 illustrates an in-ear headphone device according to an embodiment of the present invention having a microphone layout. [Figure 3b] 10A-10C illustrate another in-ear headphone device according to an embodiment of the present invention having another microphone layout. [Figure 3c] 10A-10C illustrate another in-ear headphone device according to an embodiment of the present invention having another microphone layout. [Figure 4] FIG. 1 illustrates an in-ear headphone device with dynamic acoustic leakage. [Figure 5a] 1 illustrates an attenuated vent layout according to an embodiment of the present invention. [Figure 5b] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5c]10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5d] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5e] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5f] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5g] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 5h] 10A-10C illustrate alternative layouts of attenuated vents in accordance with embodiments of the present invention. [Figure 6a] 10A-10C illustrate the effect of using acoustic impedance reducing elements according to some embodiments of the present invention. [Figure 6b] FIG. 10 is another diagram illustrating the effect of using an acoustic impedance reducing element according to some embodiments of the present invention. [Figure 6c] FIG. 10 is another diagram illustrating the effect of using an acoustic impedance reducing element according to some embodiments of the present invention. [Figure 7a] FIG. 1 illustrates one beneficial effect of the damped vent in relation to dynamic acoustic leakage, according to a preferred embodiment of the present invention. [Figure 7b] FIG. 10 is another diagram illustrating one beneficial effect of the damped vent in relation to dynamic acoustic leakage, according to a preferred embodiment of the present invention. [Figure 8a] Diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8b] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8c] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8d] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8e] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8f] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 8g] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with inward directed noise. [Figure 9a] Diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9b] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9c] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9d] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9e] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9f] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 9g] Another diagram showing a simulated in-ear headphone device under the influence of dynamic acoustic leakage associated with audio reproduction. [Figure 10a] 10A and 10B illustrate the effect of user variation in different scenarios. [Figure 10b] Another diagram showing the effect of user variation in different scenarios. [Figure 10c] Another diagram showing the effect of user variation in different scenarios. DETAILED DESCRIPTION OF THE INVENTION

[0148] Figure 1 illustrates an in-ear headphone device 101 according to an embodiment of the present invention. The diagram in Figure 1 shows the in-ear headphone device 101 when inserted into the ear canal 110 of a user wearing the device. The in-ear headphone device 101 is preferably provided with flexible ear tips 112 for resting within the user's outer ear 111 and for providing acoustic sealing within the different user's ear canals 110.

[0149] The in-ear headphone device 101 includes attenuating vents 105 that acoustically couple the external acoustic environment 109 to the ear canal 110 outward from the ear canal 110. Ideally, the in-ear headphone device 101 has an exterior shape that blocks the user's ear canal 110, however, small leak paths (not shown) may naturally occur at the interface between the flexible ear tips 112 and the ear canal 110, and these leaks may change dynamically as the user moves around and, for example, when the user is talking or chewing.

[0150] The attenuated vent 105 in this embodiment comprises a vent element 106 preferably formed as a circular or semi-circular conduit, although other vent element designs are contemplated. The purpose of the attenuated vent is to facilitate the transmission of acoustic sound, but at a reduced sound pressure level (SPL), between the external acoustic environment 109 and the ear canal 110. The attenuation characteristics of the attenuated vent 105 are provided by a damping element 107, which in this embodiment is a damping fabric located at one end of the attenuated vent 105. In another embodiment of the invention, the attenuation characteristics of the attenuated vent 105 are provided by a damping fabric at both ends of the attenuated vent 105, and in yet another embodiment of the invention, the attenuation characteristics of the attenuated vent 105 are provided by slits or openings in the vent element 106.

[0151] The in-ear headphone device 101 comprises a noise microphone 102 configured to primarily record acoustic sounds from an external acoustic environment 109 and provide a recorded audio signal RAS. While in the illustration of this embodiment the noise microphone 102 is shown configured at the end of the in-ear headphone device 101 facing the external acoustic environment, in other embodiments of the present invention the noise microphone 102 may be configured further within the in-ear headphone device 101 and acoustically coupled to the external acoustic environment 109 by a microphone duct (not shown). The in-ear headphone device 101 further comprises a signal processor 103 configured to receive the recorded audio signal RAS and to provide an active noise control signal ANCS based on the received recorded audio signal RAS. The loudspeaker 104 of the in-ear headphone device 101 is configured to reproduce the provided active noise control signal ANCS in an ear canal 110 of a user of the in-ear headphone device 101. In the illustration of this embodiment, the loudspeaker 104 is shown included within the in-ear headphone device 101, with acoustic sound emitted by the loudspeaker being directed to the ear canal 110 via the loudspeaker duct 108. However, the loudspeaker duct 108 may be omitted in other embodiments of the invention, and the loudspeaker 104 may be configured closer to the end of the in-ear headphone device 101 that faces the ear canal. In yet other embodiments of the invention, the loudspeaker duct 108 and the attenuated vent 105 may be formed as two acoustically separated sub-sections of a combined acoustic port.

[0152] The in-ear headphone device 101 according to the present invention is configured to reproduce an active noise control signal and is therefore capable of performing a method referred to as active noise control or active noise cancellation: unwanted sounds from the external acoustic environment 109 are recorded by the noise microphone 102 and, based on the recorded audio signal RAS, the signal processor 104 provides an active noise control signal ANCS which, when reproduced by the loudspeaker 104, is designed to cancel the unwanted sounds in the user's ear canal 110 by destructive interference.

[0153] FIG. 2 shows an example inward vent transfer function H VI The inward vent transfer function H VI can be understood as the transfer function from the external environment to the ear canal, substantially free of contributions from dynamic acoustic leakage or loudspeakers. Three representations of the inward vent transfer function are shown as curves S1 through S3. In accordance with the present invention, one or more damping elements are added to the inward vent transfer function H VI The acoustic resonance of the

[0154] The diagram displays a reference frequency range 403 from 20 Hz to 100 Hz. Based on the reference frequency range 403, a reference magnitude 400 is determined, for example, by the inward vent transfer function H VI Based on the reference magnitude 400, a resonance magnitude threshold 401 may be determined, for example, the reference magnitude threshold 401 may be 3 dB greater than the reference magnitude 400.

[0155] Curve S1 represents the inward vent transfer function H for an in-ear headphone device with a vent that has no substantial attenuation. VI As a result, curve S1 is characterized by a resonance magnitude 405 that exceeds a resonance magnitude threshold 401. A device according to curve S1 cannot incorporate the benefits of the present invention and is not disclosed by the claims.

[0156] Curve S2 is the inward vent transfer function H for an in-ear headphone device with damped vents. VI Curve S2 is characterized by a resonance magnitude 405 that falls within the resonance magnitude threshold 401 according to the present invention.

[0157] Curve S3 is the inward vent transfer function H for an in-ear headphone device with damped vents. VI The resonance magnitude 405 of curve S3 is approximately the same as the reference magnitude 400. The acoustic resonance of the damped vent may be, for example, approximately critically damped. Thus, the resonance magnitude 405 of curve S3 falls within the resonance magnitude threshold 401.

[0158] 3a-3c show various in-ear headphone devices 101 according to embodiments of the present invention having different microphone layouts. 3a shows the in-ear headphone device 101 of FIG. 1 when inserted into a user's ear canal 110, again in accordance with a preferred embodiment of the present invention. When in use, the in-ear headphone device 101 is configured to provide reproduction of at least an active noise control signal ANCS, and this reproduced signal in the form of acoustic sound waves is combined in the ear canal 110 with sounds emanating from unwanted sound sources, such as the rumble of an airplane engine or train or bus wheels if a user of the in-ear headphone device 101 is commuting by airplane, train, or bus, respectively. The active noise control signal ANCS is designed to cancel, e.g., counteract, the unwanted sounds, so that the combined sounds picked up by the user's eardrum 201 are effectively perceived as an acoustic null signal.

[0159] This layout of the noise microphone 102 causes the noise microphone 102 to primarily record sounds from the external acoustic environment around the user, which indirectly represent unwanted sounds as perceived by the user through the headphone device.

[0160] 3b shows an alternative embodiment of the present invention in which a noise microphone 102 is configured within an in-ear headphone device 101 so as to record sounds within the ear canal 110 of a user wearing the in-ear headphone device. With this layout of the noise microphone 102, the noise microphone 102 primarily records sounds from within the user's ear canal, i.e., provides a somewhat direct measure of unwanted sounds as perceived by the user.

[0161] Figure 3c shows yet another alternative embodiment of the present invention, in which the noise microphone 102 is configured in a similar manner to the noise microphone 102 shown in the embodiment of Figure 3b. In this embodiment of the present invention, the in-ear headphone device 101 further comprises an auxiliary microphone 202, which is located within the in-ear headphone device 101 similar to the noise microphone 102 of the embodiment shown in Figure 3a.

[0162] FIG. 4 illustrates an in-ear headphone device 101 similar to the in-ear headphone device 101 shown in the embodiment of FIG. 3a inserted into the ear canal 110 of a user wearing the device. Ideally, flexible ear tips 112 (not shown) would form a perfect seal between the in-ear headphone device 101 and the user's ear; however, in practice, such a perfect seal may not be established, and a small amount of leakage may exist. The figure illustrates acoustic leakage 203 formed between the in-ear headphone device 101 and the user's ear. Acoustic leakage 203 may take any size and geometric shape, depending on the shape of the user's ear and how the in-ear headphone device 101 is inserted into the ear canal 110. Additionally, additional leakage paths (not shown) may also exist, which may also take any size and geometric shape. For convenience, any configuration of leakage in the seal between the in-ear headphone device 101 and the user's ear may be referred to as the leakage path 203, and therefore may be an effective leakage path. The acoustic leakage 203 may also change dynamically, i.e., over time, as the user moves around, for example, when the user is walking or jogging, and when the user moves their jawbone, such as when talking.

[0163] The dynamically changing acoustic leakage 203 presents a gateway for unwanted sounds from the external acoustic environment 109 to enter the user's ear canal 110. As can be understood with reference to Figure 4, the in-ear headphone device 101 according to any of the embodiments shown thus far may also exhibit acoustic leakage 203 when inserted into a user's ear, for example, due to the in-ear headphone device 101 being improperly fitted.

[0164] In addition to acoustic leakage 203, attenuation vent 105 also presents a gateway for unwanted sound from the external acoustic environment 109 to enter the user's ear canal 110. However, unwanted sound from the external acoustic environment 109 that enters through acoustic leakage 203 can exit through attenuation vent 105. In this way, the attenuation vent serves a dual purpose: sound can enter the ear canal 110 from the external acoustic environment 109, and sound that passes through acoustic leakage 203 can exit through attenuation vent 105 and return to the external acoustic environment 109.

[0165] 5a-h show various layouts of attenuated vents 105 according to embodiments of the present invention. 5a shows a side view of a damped vent 105 according to an embodiment of the present invention. The damped vent 105 comprises a vent element 106 in the form of a cylinder and a damping element 107 in the form of a damping fabric. Although the vent element 106 is shown in this embodiment as a cylindrical element, other geometric shapes are contemplated.

[0166] Although the damping element 107 in the form of a damping fabric is shown located at one end of the vent element 106, it may be located within either end of the vent element 106, and in another embodiment of the present invention, the damped vent 105 includes damping elements 107 within both ends of the damped vent 105. The damping element 107 in this embodiment is located within the opening of the vent element 106, but in another embodiment of the present invention, the damping element 107 may be located so as to cover the opening of the vent element 106.

[0167] 5b shows a side view of an attenuated vent 105 according to an embodiment of the present invention. Several vent elements 106 form a branched attenuated vent 105 that further comprises a damping element 107 in the form of a damping fabric. While the damping element 107 in this embodiment is disposed within the opening of the vent element 106, in other embodiments of the present invention, the damping element 107 may be disposed to cover the opening of the vent element 106. Furthermore, in other embodiments of the present invention, the branched attenuated vent may comprise any number of damping elements 107, such as damping elements 107 that cover all of the openings of the vent element 106.

[0168] FIGS. 5c-5d show two side views of an attenuated vent 105 according to an embodiment of the present invention. FIG. 5c shows the attenuated vent 105 constructed with a loudspeaker duct 108 to which a loudspeaker 103 may be acoustically coupled. In this embodiment of the present invention, the loudspeaker duct 108 and the attenuated vent 105 form a cylindrical acoustic tube, i.e., each of the two has a semi-cylindrical geometry. In other embodiments of the present invention, the loudspeaker duct 108 and the attenuated vent 105 can form a combined acoustic tube having any geometry. In FIG. 5c, a dotted line cc is shown representing plane c. In FIG. 5d, a view of the embodiment from plane c is shown, illustrating the longitudinal geometry of the combined loudspeaker duct 108 and attenuated vent 105.

[0169] Figure 5e illustrates an embodiment of the present invention in which an in-ear headphone device 101 (not shown) comprises two separate damped vents 105. Each damped vent 105 is similar to the damped vent 101 illustrated in connection with the embodiment of Figure 5a. In a similar manner, the structure of the damped vent 105 in Figure 5e comprises a vent element 106 and a damping element 107. The damping element 107 in this embodiment is a damping fabric residing within the opening of the vent element 106, although other structures of the damping element are contemplated.

[0170] 5f shows an embodiment of the invention in which the damping feature of the damped vent 105 is facilitated by a damping element 107 in the form of a slit. In another embodiment, the damping element 107 is incorporated within the vent element 106, for example, to impede air flow or facilitate air leakage.

[0171] FIG. 5g illustrates an embodiment of the present invention in which a microphone, e.g., noise microphone 102, is configured to primarily record sound from attenuated vent 105. The microphone may therefore be considered to be acoustically coupled to a vent element 106 of attenuated vent 105 within in-ear headphone device 101. In other embodiments, in-ear headphone device 101 comprises several vent elements 106, and a microphone and / or loudspeaker may be coupled to any of these vent elements 106 in accordance with embodiments of the present invention. In the embodiment illustrated in FIG. 5g, attenuated vent 105 has a single attenuating element 107 on one side. In such an embodiment, the microphone may therefore primarily record sound from the external environment or primarily record sound from the ear canal, depending on the exact placement of attenuating element 107 and the microphone.

[0172] 5h shows an embodiment of the invention in which the loudspeaker duct 108 and the attenuated vent are partially coupled by a damping element 107. The attenuated vent 105 also further comprises damping elements 107 on either end of the vent element 106. The loudspeaker duct 108 and the attenuated vent 105 can feature any type of partition, according to embodiments of the invention. The loudspeaker 103 can, for example, be acoustically coupled to the attenuated vent 105 in the in-ear headphone device 101, acoustically decoupled from the attenuated vent 105 in the in-ear headphone device 101 (see, for example, FIG. 5c), or partially coupled to the attenuated vent 105 in the in-ear headphone device 101, as shown in FIG. 5h.

[0173] In the above-described embodiments of the present invention, various structures of the attenuated vent 105 are demonstrated. However, the present invention is not limited to any particular structure, and thus various other embodiments are available to those skilled in the art. The attenuated vent structure may be realized by any combination of the above-described embodiments. Thus, the attenuated vent structure may include one or more attenuated vents 105, an individual attenuated vent may include any number of vent elements 106 and attenuation elements 107, microphones and / or loudspeakers may be acoustically coupled to the vent elements or may have individual ducts, and the vents and ducts may have any geometric shape.

[0174] 6a-6c show the effect of using damping elements of various acoustic impedances according to some embodiments of the present invention compared to an open ear. The presented data was obtained by running a simulation of the system using an equivalent electronics diagram as shown in FIG. 6a, which can be replicated by one skilled in the art.

[0175] The simulation shown in FIG. 6a corresponds to an exemplary embodiment of the present invention. A 60 dB signal simulation source 300 corresponds to noise from the external environment, and an upper ear simulation microphone 301 corresponds to sound heard by the ear. In this simulation, sound can enter the ear canal via two different paths: vent diagram path 302 and leak diagram path 304. Vent diagram path 302 splits so that a first portion of the vent diagram path consists of two vent elements, which merge into a single vent element. Leak diagram path 304 has a large acoustic impedance, which corresponds to substantially no dynamic acoustic leakage in this particular simulation.

[0176] Bent diagram path 302 has an impedance Rv, which corresponds to a damping element according to the present invention. For Figures 6b-6c, the value of this impedance is varied to simulate the effect of using damping elements of different acoustic impedances.

[0177] In Figure 6b, simulated curve S4 shows the signal corresponding to an open ear, which has a characteristic resonance at about 3 kHz. Simulated curves S5-S9 correspond to acoustic impedances Rv of 0, 45, 90, 180, and 360 acoustic ohms, respectively, where all values ​​provided are in CGS units of acoustic ohms. As is evident from the simulation, a resonance is clearly present at approximately 900 Hz when the acoustic impedance is low. However, as the acoustic impedance is increased, the resonance is attenuated, and for sufficiently large acoustic impedances, no resonance peak feature is visible. If a very large acoustic impedance is selected, not only the resonance but a wide range of frequencies are attenuated. Therefore, in this simulated embodiment, a preferred acoustic impedance is approximately 180 acoustic ohms, because the resonance feature is eliminated but otherwise sound below the desired cutoff frequency is not substantially attenuated.

[0178] For different embodiments of the present invention, the preferred acoustic impedance of the damping element may vary. The acoustic impedance may depend, for example, on the composition of the vent element, the cross-sectional area of ​​the vent element, the length of the vent element, and the remaining volume of the ear canal when the device is inserted. The primary purpose of the damping element is typically to eliminate the Helmholtz resonance signature without unnecessarily attenuating further sound, and therefore the acoustic impedance must be selected accordingly.

[0179] Some embodiments of the present invention may also include several damping elements, the combined effect of which should preferably be to suppress Helmholtz resonance that would occur without the damping elements when the device is inserted.

[0180] FIG. 6b additionally illustrates how the attenuated vent can reduce sound pressure in the ear at frequencies above the desired cutoff. Compared to an open ear, attenuation can reach 20 dB or more in the region of open-canal resonances. At higher frequencies, resonances that can vary greatly from ear to ear can also be attenuated by the attenuated vent in combination with other acoustic factors, such as attenuated entrances to the cavity and the front volume of a loudspeaker. In the exemplary illustration of the figure, the difference in sound pressure level magnitude between the peak values ​​of the two resonance features of curves S5-S9 and curve S4 at approximately 8 kHz and approximately 9 kHz, respectively, is 9 dB. This attenuation effect at relatively high frequencies may be preferential in some embodiments of the present invention.

[0181] Figure 6c shows the same curves as Figure 6b, but now the curves are plotted against a simulated curve associated with an open ear, S4. The curves shown in Figure 6c can therefore be interpreted as passive insertion gain, i.e., the change in gain experienced by a user when the device is worn in an inoperative state. Note that the simulation data has been truncated at approximately 6.5 kHz for simplicity. While the insertion gain data in this frequency region is visibly affected by the resonance features at 8 kHz to 9 kHz shown in Figure 6b, the detailed variations in these features do not significantly affect the overall perception of sound under normal conditions with a common signal.

[0182] 7a-7b illustrate one beneficial effect of the damped vent 105 according to a preferred embodiment of the present invention. The data presented was obtained by running a simulation of the system using an equivalent electronics diagram as shown in FIG. 7a, which can be replicated by one skilled in the art.

[0183] The simulation shown at the top of Figure 7a corresponds to an exemplary embodiment of the present invention with an attenuated vent, while the bottom corresponds to an in-ear headphone device without an attenuated vent. The 60 dB SPL signal simulation source 300 corresponds to noise at the entrance to the concha from the external environment, and the ear simulation microphone 301 corresponds to sound heard within the ear of the two simulated devices. In the simulation of the exemplary embodiment of the present invention, the signal can enter the ear canal via three different paths: vent diagram path 302, electroacoustic diagram path 303, and leakage diagram path 304. However, in the simulation shown in Figures 7a-b, the signal simulation source 300 is only connected to the ear simulation microphone 301 via leakage diagram path 304. Therefore, this simulation relates to sound entering the ear through dynamic acoustic leakage. The signal entering through leakage diagram path 304 can exit through vent diagram path 302, and the signal recorded by the ear simulation microphone 301 is therefore degraded.

[0184] Both leakage diagram paths 304 of both simulated devices in Figure 7a comprise diagram elements with a leakage diameter Dlk / DLK, which corresponds to the diameter of the dynamic acoustic leakage. In each figure, this leakage diameter is varied to show the effect that dynamic acoustic leakage can have on the signal reaching the ear simulation microphone 301.

[0185] Figure 7b shows the signal arriving at the ear-simulation microphone, where curves S16-S20 correspond to a simulated in-ear headphone device with attenuated vents and curves S21-S25 correspond to a simulated device without attenuated vents. Curves S16-S20 and S21-S25 correspond to leakages with combined cross-sectional areas equal to circular cross sections with diameters of 0.035 cm, 0.05 cm, 0.07 cm, 0.08 cm, and 0.1 cm, respectively.

[0186] For simulated curves S21-S25, any signal that enters the region of ear simulation microphone 301 tends to remain in ear simulation microphone 301, thus resulting in a large signal being recorded. In contrast, for simulated curves S16-S25, the sound pressure level recorded by ear simulation microphone 301 is significantly lower because signals within the region of ear simulation microphone 301 can leave this region through vent diagram path 302. For example, for a leakage diameter of 0.05 cm, the difference in sound pressure level contributed by leakage at 200 Hz is approximately 12 dB between the simulated devices as displayed by curves S17 and S22.

[0187] The simulations and their results, as shown in Figures 7a-b, serve as evidence that embodiments of the present invention can reduce the effects of dynamic acoustic leakage within the ear canal by allowing sound to exit through attenuated vents.

[0188] Figures 8a-g show various in-ear headphone devices simulated under the influence of dynamic acoustic leakage, with the devices having no vents, open unattenuated vents, or attenuated vents.

[0189] The data presented was obtained by running a simulation of the system using an equivalent electronics diagram as shown in Figure 8a, which can be reproduced by one skilled in the art.

[0190] The simulation diagram shown in Figure 8a corresponds to an in-ear headphone device. A 60 dB SPL constant pressure signal simulation source 300 corresponds to noise at the entrance of the concha from the external environment, and ear simulation microphone 301 corresponds to sound heard within the ear. The signal can reach ear simulation microphone 301 via three different paths: vent diagram path 302, electroacoustic diagram path 303, and leakage diagram path 304. However, in the simulations associated with Figures 8a-g, electroacoustic diagram path 303 does not carry a signal.

[0191] The vent diagram path 302 is split so that a first portion of the vent diagram path consists of two vent elements that merge into a single vent element where impedance Rv is located. For various Figures 8b-8c, 8d-8e, and 8f-8g, the impedance value is varied to simulate a device with no vent (large impedance), a device with an open, undamped vent (small impedance), and a damped vent (intermediate impedance), respectively.

[0192] The leakage diagram path 304 has a leakage diameter Dlk / DLK that corresponds to the equivalent diameter of the dynamic acoustic leakage. In each figure, this leakage diameter is varied to show the effect that the dynamic acoustic leakage can have on the signal reaching the ear simulation microphone 301.

[0193] Figures 8b-8c show the signal reaching the ear-simulation microphone 301 for a device without a vent, i.e., Rv = 1 megaohm (acoustic) in CGS units, where Figure 8b shows the magnitude of the sound pressure level of the transmitted signal and Figure 8c shows the phase of the transmitted signal. Both of these entities are relevant for active noise control. Curves S26-S28 and S29-S31 correspond to leakage diameters of 0.05 cm, 0.07 cm, and 0.1 cm, respectively.

[0194] Figure 8b shows how dynamic leakage affects the signal magnitude, e.g., the inward total transfer function H TI This clearly shows how the difference in sound pressure level can affect the magnitude of the noise. In particular, in the range above 400 Hz, the difference in sound pressure level is 10 dB to 15 dB.

[0195] Furthermore, Figure 8c shows how dynamic leakage can additionally affect signal phase, especially within the range of 100 Hz to 700 Hz. Thus, these simulations demonstrate the dramatic effect that dynamic acoustic leakage can have on non-vented in-ear headphone devices.

[0196] Figures 8d-8e show the signal reaching the ear-simulation microphone 301 for an open, unattenuated vent, i.e., a device with Rv=0, where Figure 8d shows the magnitude of the sound pressure level of the transmitted signal and Figure 8e shows the phase of the transmitted signal. Both of these entities are relevant for active noise control. Curves S32-S35 and S36-S39 correspond to leakage diameters of 0 cm, 0.05 cm, 0.07 cm, and 0.1 cm, respectively.

[0197] Figure 8d shows how an in-ear headphone device with an open vent can be adversely affected by the presence of Helmholtz resonance. With the addition of dynamic acoustic leakage, the location of this resonance can shift to a different frequency, which can be problematic for continuous handling of devices configured to provide active noise control.

[0198] Figure 8e shows the signal phase in a device with an undamped vent and how dynamic acoustic leakage affects the signal phase. Below 500 Hz, the phase is relatively well behaved despite dynamic acoustic leakage. However, as we approach 1 kHz, the phase exhibits a steep downward trend. This steep transition is generally detrimental for active noise control purposes. Dynamic acoustic leakage can shift this steep transition to the periphery, further complicating this phase behavior.

[0199] Thus, these simulations show how devices with undamped vents can have serious problems in providing optimal active noise control.

[0200] Figures 8f-8g show the signal reaching the ear-simulation microphone 301 for a device with a damped vent, i.e., Rv = 180 acoustic ohms in CGS units, where Figure 8f shows the magnitude of the sound pressure level of the transmitted signal and Figure 8g shows the phase of the transmitted signal. Both of these entities are relevant for active noise control. Curves S40-S43 and S44-S47 correspond to leakage diameters of 0 cm, 0.05 cm, 0.07 cm, and 0.1 cm, respectively.

[0201] Figure 8f shows how dynamic leakage can affect signal magnitude. Compared to simulations for devices without vents (Figures 8b-8c), the effect of leakage is minimal. For example, at 1 kHz, the difference in sound pressure level between 0.05 cm and 0.1 cm leakage diameters is approximately 3 dB with the damped vent, while the difference is approximately 15 dB without the vent. Compared to simulations with undamped vents (Figures 8d-8e), the simulations with the damped vent do not display a Helmholtz resonance. As the leakage increases, a resonance-like feature occurs, but this feature is better behaved than the Helmholtz resonance shown in Figure 8d, which shifts in frequency as the leakage size is changed.

[0202] Figure 8g shows the signal phase for a device with damped vents and how dynamic acoustic leakage affects this signal phase. Over the entire range of frequencies relevant for active noise control, up to approximately 1 kHz, the phase is well behaved for any of the simulated dynamic acoustic leakage.

[0203] Therefore, the simulations in Figures 8a-8g provide evidence that in-ear headphone devices with attenuated vents are superior for active noise control purposes compared to devices without vents and devices with non-attenuated vents in the context of dynamic sound leakage. In particular, the dynamic sound leakage is related to the inward total transfer function H TI can be reduced, and the dynamic acoustic leakage can be reduced by the inward total transfer function H TI It has been shown that distortions due to affecting the phase of the harmonics can be reduced. These improvements can be obtained by controlling and attenuating the Helmholtz resonance established by the ear canal and the acoustic path to the environment.

[0204] 9a-g show various in-ear headphone devices simulated under the influence of dynamic acoustic leakage, with the devices having no vent, an open unattenuated vent, or an attenuated vent. In particular, the electroacoustic diagram path includes a simulated loudspeaker that generates a signal that is sent to an ear-simulation microphone 301.

[0205] The data presented was obtained by running a simulation of the system using an equivalent electronics diagram as shown in Figure 9a, which can be reproduced by one skilled in the art.

[0206] The simulation diagram shown in FIG. 9a corresponds to an in-ear headphone device. For illustrative purposes, a simple loudspeaker model consisting of a constant volume velocity source and a front volume is established. The simulated loudspeaker sends a signal to the ear canal through diagram path 303. The amplitude of the constant volume velocity source is adjusted to produce a signal of approximately 60 dB SPL at low frequencies within the ear simulation microphone 301. The behavior of this signal at the ear simulation microphone 301 is relevant for active noise control and reproduction of the desired audio signal. The signal can typically partially reach the ear simulation microphone 301 and partially exit the simulated ear canal region through vent diagram path 302 and leakage diagram path 304.

[0207] Vent diagram path 302 is split so that a first portion of the vent diagram path consists of two vent elements that merge into a single vent element where impedance Rv is located. For various Figures 9b-9c, 9d-9e, and 9f-9g, the impedance value is varied to simulate a device with no vent (large impedance), a device with an open, unattenuated vent (small impedance), and an attenuated vent (intermediate impedance), respectively.

[0208] The leak diagram path 304 has a leak diameter Dlk / DLK, which corresponds to the cross section of the dynamic acoustic leakage. In each figure, this leak diameter is varied to show the effect that the dynamic acoustic leakage can have on the signal reaching the ear simulation microphone 301.

[0209] 9b-9c show the signal reaching the ear-simulation microphone 301 for a device without a vent, i.e., Rv = 1 megaohm (acoustic) in CGS units, where FIG. 9b shows the magnitude of the sound pressure level of the signal and FIG. 9c shows the magnitude of the sound pressure level of the signal relative to a reference signal with no dynamic acoustic leakage. Curves S48-S53 and S54-S59 correspond to leakage diameters of 0 cm, 0.03 cm, 0.05 cm, 0.07 cm, 0.08 cm, and 0.1 cm, respectively.

[0210] 9b-9c show how dynamic leakage can affect the magnitude of the signal reaching the ear from the loudspeaker in a non-vented in-ear device, both in terms of the transfer function from the loudspeaker to the eardrum and in terms of the total outward transfer function H TO In particular, at low frequencies, the effect of leakage is very large, for example at 150 Hz, where the difference in sound pressure level between the curves shown is more than 25 dB. Furthermore, this difference in sound pressure level is significant up to above 1 kHz.

[0211] Thus, these simulations demonstrate the significant impact that dynamic acoustic leakage can have on non-vented in-ear headphone devices. Figures 9d-9e show the signal reaching the ear-simulation microphone 301 for a device with an open, unattenuated vent, i.e., Rv=0, where Figure 9b shows the magnitude of the sound pressure level of the signal and Figure 9c shows the magnitude of the sound pressure level of the signal relative to a reference signal with no dynamic acoustic leakage. Curves S60-S64 and S65-S69 correspond to leakage diameters of 0 cm, 0.03 cm, 0.05 cm, 0.07 cm, and 0.1 cm, respectively.

[0212] Figure 9d clearly shows how an in-ear headphone device with an open, unattenuated vent suffers from extensive loss of sound in relation to the impedance of the outward sound path: in particular, in the low frequency regime, the signal recorded by the ear simulation microphone 301 is 20-30 dB lower than the 60 dB signal emitted by the simulated loudspeaker.

[0213] These simulations therefore show that devices with unattenuated vents are poorly suited for sound reproduction. 9f-9g show the signal reaching the ear-simulation microphone 301 for a device with a damped vent, i.e., Rv = 180 acoustic ohms in CGS units, where FIG. 9f shows the magnitude of the sound pressure level of the signal and FIG. 9g shows the magnitude of the sound pressure level of the signal relative to a reference signal with no dynamic acoustic leakage. Curves S70-S75 and S76-S80 correspond to leakage diameters of 0 cm, 0.03 cm, 0.05 cm, 0.07 cm, 0.08 cm, and 0.1 cm, respectively.

[0214] The simulated curves in Figures 9f-9g show that the magnitude difference between the simulated curves for different leak diameters is greatly reduced compared to Figures 9b-9c. Furthermore, a comparison between Figures 9d and 9f shows that the device with the damped vent does not suffer from extensive sound loss in the low frequency regime.

[0215] Therefore, the simulations in Figures 9a-9g provide evidence that in-ear headphone devices with attenuated vents are superior for active noise control purposes and sound reproduction compared to devices without vents and devices with non-attenuated vents in the context of dynamic sound leakage. The in-ear headphone devices with attenuated vents have a significantly improved outward total transfer function H TO and the outward total transfer function H due to dynamic acoustic leakage, especially at low frequencies. TOTherefore, the outward transfer function H, which affects loudspeaker feedback and active noise control, can be adjusted to provide a favorable balance between the TO It has been shown that distortion due to the effects of dynamic acoustic leakage on the eardrum can be reduced while limiting the reduction in sound pressure from the loudspeaker at the eardrum due to sound exiting through the vent.

[0216] Figures 10a-10c show the effect of user variability, such as different ear canal sizes and different insertion positions between users, in different scenarios: open ear, in-ear device with open vent, and in-ear headphone device with attenuated vent.

[0217] The simulation diagrams shown in Figure 10a correspond (from top to bottom) to an in-ear headphone device with attenuated vents, a canal-type device, an open ear, and a reference open ear. The 60 dB signal simulation source 300 corresponds to noise from the external environment, and the various ear simulation microphones 301 correspond to sounds heard in the ear in different scenarios.

[0218] A diagram element is located in front of the ear simulation microphone 301, simulating an ear canal. In this simulation, the simulated ear canal is determined by the parameter vLcnl / CLCNL, which corresponds to the size of a portion of the ear canal, and this parameter is varied to investigate the effect of user variability. The diagram element after the reference open ear diagram path 307, which simulates the ear canal, is not varied, and the simulated signal recorded by the corresponding ear simulation microphone is used as a reference.

[0219] Figure 10b shows the signal arriving at various ear-simulation microphones, where curves S81-S83 correspond to a simulated in-ear headphone device with attenuated vents, curves S84-S86 correspond to a simulated canal device, and curves S87-S89 correspond to an open ear. The simulated sizes of the portion of the ear canal are -0.2 cm, 0 cm, and 0.2 cm in each scenario.

[0220] In general, above 6-7 kHz, all curves are dominated by steep resonance features. These features are typical of the ear at these frequencies. Inserting an in-ear headphone device can alter these features, but the resonance behavior typically persists in some form.

[0221] Additionally, the open-ear curves S87-S89 all display the well-known natural resonance of the ear at approximately 3 kHz, and the canal-type curves S84-S86 display the Helmholtz resonance at approximately 1 kHz. In contrast, the damped-vent curves S81-S83 do not exhibit any resonance characteristics below 6-7 kHz.

[0222] Active noise control is typically implemented at frequencies up to 1 kHz. In this range, it is primarily the in-ear curves S84-S86 that are affected by user variation. In contrast, the damped vent curves S81-S83 are only minimally affected.

[0223] Figure 10c shows the same curve as Figure 10b, but now shown relative to the curve obtained by the reference open ear diagram path 307. The curve shown in Figure 10c can therefore be interpreted as the passive insertion gain, i.e., the change in gain experienced by a user when an inactive device is worn.

[0224] The simulations of Figures 10a-10c provide evidence that in the context of user variation, an in-ear headphone device with attenuated vents is an improvement over an in-ear device with open vents. In particular, the simulations demonstrate that, according to embodiments of the present invention, user variation is reduced by the inward total transfer function H TI This shows that distortion due to affecting the magnitude of the [Explanation of symbols]

[0225] 101 In-ear headphone devices 102 Noise Microphone 103 Signal Processor 104 loudspeaker 105 Damped Vent 106 Vent Element 107 Damping Elements 108 Loudspeaker Duct 109 External acoustic environment 110 External auditory canal 111 Auricle (external ear) 112 Flexible Ear Tips 201 Eardrum (tympanic membrane) 202 Auxiliary Microphone 203 Sound Leak 300 Signal Simulation Source 301 Ear Simulation Microphone 302 Bent Diagram Path 303 Electroacoustic Diagram Path 304 Leakage Diagram Path 305 Open Ear Diagram Pathway 306 Canal Type Diagram Path 307 Reference Open Ear Diagram Path 400 standard size 401 Threshold of Resonance Magnitude 402 Size Threshold Distance 403 Reference Frequency Range 404 Resonant Frequency Range 405 Resonance Magnitude S1~S97 Simulation signal curve RAS Recorded Audio Signal ANCS Active Noise Control Signal H VI ,H vo Inward vent transfer function, outward vent transfer function H LI ,H LO Inward leakage transfer function, outward leakage transfer function H TI ,H TO Inward total transfer function, outward total transfer function H EI Inward electroacoustic transfer function

Claims

1. An in-ear headphone device (101) for insertion into a human ear canal (110), comprising: a noise microphone (102), a loudspeaker (104), and a signal processor (103) configured to provide an active noise control signal (ANCS) based on a recorded speech signal (RAS) from the noise microphone (102), wherein the loudspeaker (104) is configured to reproduce the active noise control signal (ANCS) in the ear canal (110); an attenuated vent (105) comprising one or more vent elements (106) and one or more damping elements (107), the attenuated vent (105) configured to couple the ear canal (110) to an external acoustic environment (109); The attenuated vent (105) has an inward vent transfer function H from the external acoustic environment (109) to the ear canal (110). ＶＩ is characterized by The damped vent (105) has an inward vent transfer function H of the damped vent (105) within a resonant frequency range (404) of 100 Hz to 2 kHz. ＶＩ The magnitude of the resonance (405) of the inward vent transfer function H ＶＩ and configured to attenuate acoustic resonance of the one or more vent elements (106) to a magnitude at most 3 dB greater than a reference magnitude (400) of An in-ear headphone device (101), wherein the inward vent transfer function H VI and the acoustic resonance are characteristics of the attenuated vent (105) when the in-ear headphone device (101) is inserted into the person's ear canal (110).

2. 2. The in-ear headphone device (101) of claim 1, wherein the loudspeaker (104) and the attenuated vent (105) are acoustically separated inside the in-ear headphone device (101).

3. 3. The in-ear headphone device (101) of claim 2, wherein the loudspeaker (104) and the damped vent (105) are acoustically separated inside the in-ear headphone device (101) by a damping element (107).

4. 4. The in-ear headphone device (101) of claim 1, wherein the loudspeaker (104) and the attenuated vent (105) are coupled to the ear canal (110) by respective ducts (106, 108).

5. 5. The in-ear headphone device (101) of claim 1, wherein the noise microphone (102) is configured to primarily record sounds from at least one of the external acoustic environment (109) and the ear canal (110).

6. The in-ear headphone device (101) according to any one of claims 1 to 5, wherein the in-ear headphone device (101) comprises an auxiliary microphone (202).

7. The signal processor (103) calculates the estimated inward total transfer function H ＴＩ 7. An in-ear headphone device (101) according to any one of claims 1 to 6, for providing the active noise control signal (ANCS) based on:

8. The estimated inward total transfer function H ＴＩ is the inward vent transfer function H ＶＩ the difference between the sound recordings of the external acoustic environment (109) and the ear canal (110), and the estimated outward total transfer function H ＴＯ 8. The in-ear headphone device (101) of claim 7, based on at least one of:

9. The estimated outward total transfer function H ＴＯ 9. The in-ear headphone device (101) of claim 8, wherein the noise level is based on the difference between the sound reproduced by the loudspeaker (104) and the sound recorded by the noise microphone (102).

10. 10. The in-ear headphone device (101) of any one of claims 1 to 9, wherein the signal processor (103) is configured with an active noise control algorithm for providing the active noise control signal (ANCS).

11. The estimated inward total transfer function H ＴＩ is the inward leakage transfer function H ＬＩ and a time-varying inward transfer function component having the inward vent transfer function H ＶＩ 10. The in-ear headphone device (101) of any one of claims 7 to 9, having a static inward transfer function component having:

12. The signal processor (103) calculates the estimated inward total transfer function H ＴＩ 12. An in-ear headphone device (101) according to any one of claims 7 to 9 and 11, configured to update a representation of

13. the signal processor (103) is configured to provide an active occlusion control signal, and the loudspeaker (104) is configured to reproduce the active occlusion control signal in the ear canal (110); 13. An in-ear headphone device (101) according to any one of claims 1 to 12, wherein the active occlusion control signal is based on a signal recorded from a microphone (102; 202) configured to primarily record sounds from the ear canal (110).

14. 14. The in-ear headphone device (101) according to any one of claims 1 to 13, further comprising an electro-acoustic path (303) comprising a microphone (102; 202) that primarily records ambient sounds, a variable gain, and the loudspeaker (104), the electro-acoustic path (303) being configured to couple the external acoustic environment (109) to the ear canal (110).

15. The electroacoustic path (303) has an inward electrical transfer function H having a high-pass characteristic with a high-pass cutoff frequency. ＥＩ 15. The in-ear headphone device (101) according to claim 14, characterized by:

16. 16. The in-ear headphone device (101) of claim 14 or 15, wherein the electro-acoustic path (303) is configured to apply a high-pass gain for frequencies above a high-pass cut-off frequency.

17. 17. The in-ear headphone device (101) according to any one of the preceding claims, wherein the one or more vent elements (106) comprise one or more of the one or more damping elements (107).

18. 18. The in-ear headphone device (101) of any one of claims 1 to 17, wherein the one or more damping elements (107) are characterized by an acoustic impedance, the acoustic impedance being in the range of 20 acoustic ohms to 500 acoustic ohms.

19. A first in-ear headphone device (101) according to any one of claims 1 to 18, a second in-ear headphone device (101) according to any one of claims 1 to 18, The first in-ear headphone device (101) is configured to fit into a first outer ear (111) of a user; An in-ear headphone device set, wherein the second in-ear headphone device (101) is configured to be fitted to a second outer ear (111) of the user.

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