Fully open earphones and active noise reduction method thereof

Abstract

The present application provides a fully open headset and an active noise reduction method thereof, which relate to the field of noise reduction technology. The active noise reduction method of the fully open headset comprises: determining the primary path transfer function based on the position of the microphone module and the target noise reduction position, wherein the target noise reduction position covers the ear canal entrance position; determining the secondary path transfer function of the main speaker based on the position of the main speaker and the target noise reduction position; determining the secondary path transfer function of the auxiliary speaker based on the position of the auxiliary speaker and the target noise reduction position; determining the characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker and the secondary path transfer function of the auxiliary speaker. For example, simply moving the wearing position of the in-ear headset outward will have almost no noise reduction effect. The active noise reduction method is designed for fully open headsets including a main speaker and an auxiliary speaker, effectively improving its noise reduction effect and enhancing the quality of the fully open headset.

Description

Technical Field

[0001] The present application relates to the field of noise reduction technology, and in particular to a fully open headphone and an active noise reduction method thereof. Background Art

[0002] As electronic gadgets like mobile phones and computers have become essential, demand for diverse, high-quality headphones is also increasing. Currently, active noise-canceling headphones on the market can be broadly categorized as in-ear and semi-in-ear, depending on the shape and position of the headphones relative to the ear. In-ear headphones, which penetrate the ear canal and emit a single channel sound field from a single speaker, travel directly along the ear canal to the inner ear. This closed design ensures highly consistent noise reduction performance across all headphones, but long-term wear can cause inflammation and significant hearing damage. Semi-in-ear headphones, on the other hand, place the headphones only at the ear canal opening, without penetrating the ear canal. Their sound field is not sealed, and they are typically fixed to the inner auricle. While more comfortable than in-ear headphones, these headphones suffer from significant individual variation in the inner auricle, resulting in poor fixation, significantly impacting noise reduction performance, and ultimately, poor practicality. This suggests that long-term headphone wearers undoubtedly place higher demands on comfort, hearing impact, and practicality. Summary of the Invention

[0003] In order to solve the above technical problems, the present application is proposed. The embodiments of the present application provide a fully open earphone and an active noise reduction method thereof.

[0004] In a first aspect, an embodiment of the present application provides an active noise reduction method for a fully open headphone, the fully open headphone comprising a microphone module, a speaker module, and an active noise reduction module, the speaker module comprising a main speaker and an auxiliary speaker. The active noise reduction method for the fully open headphone comprises: determining a primary path transfer function based on the position of the microphone module and a target noise reduction position, wherein the target noise reduction position covers the ear canal entrance position; determining a secondary path transfer function of the main speaker based on the position of the main speaker and the target noise reduction position; determining a secondary path transfer function of the auxiliary speaker based on the position of the auxiliary speaker and the target noise reduction position; and determining characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker.

[0005] In combination with the first aspect, in certain implementations of the first aspect, characteristic parameters of the active noise reduction module are determined based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker, including: determining dynamic constraints based on the leakage energy of the audio played in real time by the headphones; determining the characteristic parameters of the active noise reduction module based on static constraints and dynamic constraints; wherein the expression of the static constraints is determined by the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker.

[0006] In combination with the first aspect, in certain implementations of the first aspect, before determining the dynamic constraint conditions based on the leakage sound energy of the audio played in real time by the headphones, the method also includes: calling the far-field transfer function of the speaker module; determining the sound signal of the speaker module; and determining the leakage sound energy of the audio played in real time by the headphones based on the far-field transfer function of the speaker module and the sound signal of the speaker module.

[0007] In combination with the first aspect, in certain implementations of the first aspect, before determining the dynamic constraint conditions based on the leakage sound energy of the real-time audio playback of the headphones, the method also includes: determining A investigation frequencies based on the frequency limit and spectral density of the real-time audio playback of the headphones; for each of the A investigation frequencies, determining the leakage sound signal of the headphones corresponding to the investigation frequency; and adding the energies of the leakage sound signals corresponding to each of the A investigation frequencies to determine the leakage sound energy of the real-time audio playback of the headphones.

[0008] In combination with the first aspect, in certain implementations of the first aspect, determining the sound leakage signal of the earphone corresponding to the investigation frequency includes: determining B wavefront investigation sections of the earphone corresponding to the investigation frequency based on the effective sound leakage influence distance of the earphone; determining, for each of the B wavefront investigation sections, the far-field path transfer function from the sound of the main speaker to the wavefront investigation section and the far-field path transfer function from the sound of the auxiliary speaker to the wavefront investigation section at the investigation frequency; obtaining the sound signal of the speaker module at the investigation frequency; determining the sound leakage signal of the earphone corresponding to the investigation frequency based on the sound signal of the speaker module at the investigation frequency and the far-field path transfer function from the sound of the main speaker to each of the B wavefront investigation sections and the far-field path transfer function from the sound of the auxiliary speaker to each of the B wavefront investigation sections at the investigation frequency.

[0009] In combination with the first aspect, in certain implementations of the first aspect, determining the sound signal of the speaker module includes: determining the noise reduction signals of the main speaker and the auxiliary speaker respectively; obtaining the noise-independent signals of the main speaker and the auxiliary speaker respectively; and determining the sound signal of the speaker module based on the noise reduction signals of the main speaker and the auxiliary speaker respectively and the noise-independent signals of the main speaker and the auxiliary speaker respectively.

[0010] In the second aspect, an embodiment of the present application provides a fully open headset, which includes a functional device, which includes: a microphone module, including at least one microphone, for collecting ambient noise signals; a speaker module, including a main speaker and an auxiliary speaker, for transmitting noise-independent signals and also for transmitting noise reduction signals to reduce the noise impact of ambient noise signals on the wearer of the headset; an active noise reduction module, the characteristic parameters of the active noise reduction module are determined based on the method mentioned in the first aspect above.

[0011] In combination with the second aspect, in certain implementations of the second aspect, the earphone further includes a fixing device connected to the functional device, the fixing device being used to fix the earphone to the ear of the earphone wearer and to make the head of the earphone stick to the auricle, presenting a completely non-in-ear style.

[0012] In combination with the second aspect, in some implementations of the second aspect, the fixing device includes an ear-hanging module, which is used to connect to the base of the ear of the headphone wearer so as to hang the headphone on the ear of the headphone wearer to fix the headphone.

[0013] In combination with the second aspect, in some implementations of the second aspect, a sound outlet is provided on the head of the earphone, wherein the sound outlet is arranged facing the entrance of the ear canal of the earphone wearer, and the central axis of the auxiliary speaker is arranged non-parallel to the central axis of the main speaker.

[0014] If the wearing position of the in-ear headphones is simply moved outward, the ear canal opening will be in an unsealed state, and an open sound field will be formed between the headphones and the human ear. For the headphone designer, it is almost impossible to implement an active noise reduction solution. The active noise reduction method provided in the embodiment of the present application is designed for fully open headphones including a main speaker and an auxiliary speaker. Based on the position and target noise reduction position of the microphone module, the position and target noise reduction position of the main speaker, and the position and target noise reduction position of the auxiliary speaker, the characteristic parameters of the active noise reduction module are determined to effectively improve the noise reduction effect of such fully open headphones and enhance the quality of the fully open headphones. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG2 is a flow chart of an active noise reduction method for fully open headphones provided by an embodiment of the present application.

[0016] Figure 2 FIG2 is a flow chart of determining characteristic parameters of an active noise reduction module according to an embodiment of the present application.

[0017] Figure 3 FIG2 is a schematic diagram of a flow chart of determining characteristic parameters of an active noise reduction module provided by another embodiment of the present application.

[0018] Figure 4 FIG2 is a flow chart of determining characteristic parameters of an active noise reduction module according to another embodiment of the present application.

[0019] Figure 5 The figure shows a flow chart of determining the sound leakage signal corresponding to the inspection frequency of the earphone provided by an embodiment of the present application.

[0020] Figure 6 FIG2 is a flow chart of determining a sound signal of a speaker module according to an embodiment of the present application.

[0021] Figure 7FIG2 is a schematic diagram showing the operation of an active noise reduction method for fully open headphones provided by an embodiment of the present application.

[0022] Figure 8 FIG2 is a schematic diagram showing the structure of a functional device of a fully open earphone provided in one embodiment of the present application.

[0023] Figure 9 Shown is a schematic diagram of wearing a fully open headset provided in one embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] Today, we live in an era of rapid information development. This development is accompanied by the upgrading of electronic products. For those who wear headphones regularly, the in-ear and semi-in-ear headphones currently on the market can no longer meet their requirements for noise reduction, wearing comfort, and health benefits.

[0026] In order to solve the above technical problems, if the wearing position of the in-ear headphones is simply moved outward to improve wearing comfort and protect the hearing of the headphone user, it will lead to a significant degradation or even loss of the noise reduction function of the headphones. The fully open headphones and active noise reduction method provided in the embodiments of the present application are designed for fully open headphones including a main speaker and an auxiliary speaker. Based on the position and target noise reduction position of the microphone module, the position and target noise reduction position of the main speaker, and the position and target noise reduction position of the auxiliary speaker, the characteristic parameters of the active noise reduction module are determined to effectively improve the noise reduction effect of such fully open headphones and enhance the quality of the fully open headphones.

[0027] The following combination Figures 1 to 6 The active noise reduction method for fully open headphones mentioned in the embodiments of the present application is introduced in detail.

[0028] Figure 1 FIG. 1 is a flow chart of an active noise reduction method for fully open headphones provided by an embodiment of the present application. Figure 1 As shown, the fully open earphones provided in the embodiment of the present application include a microphone module, a speaker module, and an active noise reduction module. The speaker module includes a main speaker and an auxiliary speaker. The main speaker and the auxiliary speaker can also be speakers with the same function, which is not specifically limited here. In addition, although the embodiment of the present application only involves two speakers, it can also be expanded to multiple speakers. The active noise reduction method of the fully open earphones includes the following steps.

[0029] Step S100: determining a primary path transfer function based on the position of the microphone module and a target noise reduction position, wherein the target noise reduction position covers the ear canal entrance position.

[0030] The target noise reduction position is the designated position where noise reduction is required. For example, in order to ensure the consistency of noise reduction of batch headphones for different headphone wearers, the ear canal entrance position is selected as the target noise reduction position. In the wearing state, based on the position of the microphone module and the target noise reduction position, it can be understood as the relative position relationship between the known microphone module and the target noise reduction position, or it can be understood as the absolute position of the known microphone module and the target noise reduction position. The primary path is the transmission path of the ambient noise signal from the microphone module to the target noise reduction position, which has a corresponding transfer function. In other words, step S100, that is, determining the primary path transfer function based on the positional relationship between the microphone module and the target noise reduction position.

[0031] Step S200 : determining a secondary path transfer function of the main speaker based on the position of the main speaker and the target noise reduction position.

[0032] Similarly, when worn, the primary speaker's position and the target noise reduction position can be understood as either knowing the relative positional relationship between the two, or knowing their absolute positions. The primary speaker's secondary path is the path by which its input signal travels from the primary speaker's input to the target noise reduction position, and has a corresponding transfer function.

[0033] Step S300 : determining a secondary path transfer function of the auxiliary speaker based on the position of the auxiliary speaker and the target noise reduction position.

[0034] Similarly, when worn, the position of the auxiliary speaker and the target noise reduction position can be understood as the relative positional relationship between the auxiliary speaker and the target noise reduction position, or as the absolute positions of the auxiliary speaker and the target noise reduction position. The secondary path of the auxiliary speaker is the transfer path of its input signal from the input terminal of the auxiliary speaker to the target noise reduction position, and it has a corresponding transfer function.

[0035] Step S400 : determining characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker.

[0036] Exemplarily, the active noise reduction module includes a filter bank. Correspondingly, the characteristic parameters of the active noise reduction module include, for example, the filter coefficient matrices of at least two filters. Based on the structural position of the fully open-back headphones, such as the position of the microphone module, the position of the main speaker, and the position of the auxiliary speaker, information such as the primary path and the secondary path is determined. Based on this information, the characteristic parameters of the active noise reduction module are determined to achieve an improved active noise reduction effect.

[0037] For example, if the wearing position of the in-ear headphones is simply moved outward, the ear canal opening will be in an unsealed state, and an open sound field will be formed between the headphones and the human ear. For the headphone designer, it is almost impossible to implement an active noise reduction solution. The active noise reduction method for fully-open headphones provided in the embodiment of the present application increases the number of active noise reduction channels. For the design of fully-open headphones including a main speaker and an auxiliary speaker, the characteristic parameters of the active noise reduction module are determined based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker, so as to effectively improve the noise reduction effect of such fully-open headphones and enhance the quality of the fully-open headphones.

[0038] Figure 2 The figure shows a flow chart of determining characteristic parameters of an active noise reduction module according to an embodiment of the present application. Figure 1 Based on the embodiment shown Figure 2 The embodiment shown is described below in detail. Figure 2 The embodiment shown is Figure 1 The differences and similarities between the illustrated embodiments are not described in detail.

[0039] like Figure 2 As shown, in an embodiment of the present application, determining characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker includes the following steps.

[0040] Step S470: Determine a dynamic constraint condition based on the sound leakage energy of the audio played in real time by the earphone.

[0041] When simply moving the wearing position of the in-ear headphones outward, you can figuratively imagine that it is like placing a small public speaker near the outer ear. For other people in the same physical space as the headphone wearer, the sound leakage effect of the headphones is a factor in the quality of the headphones, and this factor needs to be considered during the design process. For example, the minimum sound leakage energy of the real-time audio playback of the headphones is used as a dynamic constraint to improve the sound leakage effect of the headphones. For example, the dynamic constraint can be selected from several positions in the physical space for investigation, or from several specific frequencies for investigation. For fully open headphones including a main speaker and an auxiliary speaker, the sound waves emitted by the two speakers cancel each other out, minimizing the impact of the headphones on the surrounding people.

[0042] Step S480: Determine characteristic parameters of the active noise reduction module based on static constraints and dynamic constraints; wherein the expression of the static constraints is determined by the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker.

[0043] Exemplarily, the static constraint condition is that the earphones have the best noise reduction effect at the target noise reduction position, that is, the active noise reduction waves at the target noise reduction position are considered to completely cancel out the ambient noise waves at that position, for example, the noise entering the ear canal is reduced to the level of in-ear headphones.

[0044] When designing open-back headphones, it's important to consider sound leakage from the perspective of others sharing the same physical space as the wearer, and also to consider the wearer's noise reduction performance. The sound field in which noise enters the ear becomes three-dimensional, and the sound produced by the speaker also becomes three-dimensional. Considering both of these perspectives simultaneously, and using a three-dimensional spatial noise reduction approach to determine the characteristic parameters of the active noise reduction module, can ensure the optimal quality of open-back headphones.

[0045] In the design process of simply moving the wearing position of the in-ear headphones outward, the noise reduction effect of the headphones is almost non-existent for the headphone wearer. At the same time, for other people in the same physical space as the headphone wearer, the headphones leak serious sound. The active noise reduction method provided in the embodiment of the present application determines the characteristic parameters of the active noise reduction module based on static constraints and dynamic constraints, and significantly reduces the in-ear noise in a three-dimensional spatial noise reduction manner, thereby improving the noise reduction performance of the headphones and the sound leakage effect of the headphones, suppressing the interference of the headphone leakage on the environment to the slightest level, and improving the quality of fully open headphones.

[0046] Figure 3 FIG. 1 is a flow chart of determining characteristic parameters of an active noise reduction module according to another embodiment of the present application. Figure 2 Based on the embodiment shown Figure 3 The embodiment shown is described below in detail. Figure 3 The embodiment shown is Figure 2 The differences and similarities between the illustrated embodiments are not described in detail.

[0047] like Figure 3 As shown, in an embodiment of the present application, before determining the dynamic constraint conditions based on the sound leakage energy of the real-time audio playback of the headphones, the following steps are also included.

[0048] Step S410: calling the far-field transfer function of the speaker module.

[0049] For example, with the speaker module as the center, different sound field radiation radii result in different regional acoustic energy. The far-field transfer function (FTF) refers to the path transfer function from the speaker module to different locations in physical (far field, away from the ear) space (the sound field radiation radius is denoted by r), denoted as S(r, ω), where ω is the angular frequency of the sound. The speaker module includes a primary speaker and a secondary speaker, so the far-field transfer function of the speaker module can also be represented by the matrix [S1(r, ω)S2(r, ω)].

[0050] Step S420: Determine the sound signal of the speaker module.

[0051] The speaker module's sound signal, i.e., the total input signal of each speaker, is frequency-dependent. The speaker module includes a main speaker and an auxiliary speaker. The speaker module's sound signal can be represented by a vector, such as

[0052] Step S430 : determining the sound leakage energy of the real-time audio played by the earphone based on the far-field transfer function of the speaker module and the loudspeaker signal of the speaker module.

[0053] In the frequency domain, the leakage energy of real-time audio playback from headphones is equivalent to the product of the leakage signal and its conjugate signal. The leakage signal is related to both the frequency and the relative distance between the position in physical space and the speaker module, and can be represented by d(r,ω). The expression of the leakage signal can be expressed as

[0054]

[0055] The sound leakage energy at the sound field radiation radius r is expressed as d(r,ω)·d * (r,ω).

[0056] The active noise reduction method for fully open headphones provided in the embodiment of the present application determines the leakage sound energy of the real-time audio playback of the headphones based on the far-field transfer function of the speaker module and the sound signal of the speaker module, providing a prerequisite for determining dynamic constraints. It is quantified in combination with the physical meaning of the signal and energy in practice, providing a scientific basis for determining the characteristic parameters of the active noise reduction module.

[0057] Figure 4 FIG. 1 is a flow chart of determining characteristic parameters of an active noise reduction module according to another embodiment of the present application. Figure 2 Based on the embodiment shown Figure 4 The embodiment shown is described below in detail. Figure 4 The embodiment shown and Figure 2 The differences and similarities between the illustrated embodiments are not described in detail.

[0058] like Figure 4As shown, in an embodiment of the present application, before determining the dynamic constraint conditions based on the sound leakage energy of the real-time audio playback of the headphones, the following steps are also included.

[0059] Step S440: Determine A inspection frequencies based on the frequency limit and spectrum density of the real-time audio played by the earphone.

[0060] The frequency limit can be determined according to the actual audio file content, such as 1200 Hz, 3000 Hz, etc.

[0061] Spectral density is used to characterize the energy distribution of audio at each frequency component.

[0062] For example, if the frequency limit is 1500 Hz and the spectrum density is mainly concentrated in the low frequency band 300-1000 Hz, the frequencies to be investigated are densely selected from this band and sparsely selected from the 0-300 Hz / 1000-1500 Hz bands.

[0063] Step S450: For each of the A inspection frequencies, determine a sound leakage signal corresponding to the earphone at the inspection frequency.

[0064] The noise reduction sound emitted by fully open headphones (based on the noise reduction signal) is intended to reduce the noise impact of ambient noise signals on the headphone wearer. In addition, fully open headphones also emit functional sounds (based on noise-independent signals such as music / audiobooks). These two sounds are both considered noise to people in the same physical space as the headphone wearer, so when considering leakage signals, the above two parts of the signals need to be considered.

[0065] Step S460 , summing the energies of the leakage sound signals corresponding to the A inspection frequencies to determine the leakage sound energy of the real-time audio played by the earphone.

[0066] Because the signal played by the speaker module is broadband, it is meaningless to consider only a single frequency. Instead, it is valuable and meaningful to sum up the energy of the leakage signal at each frequency to determine the leakage energy of the real-time audio played by the headphones.

[0067] Figure 5 The figure shows a flow chart of determining the sound leakage signal corresponding to the inspection frequency of the earphone provided by an embodiment of the present application. Figure 4 Based on the embodiment shown Figure 5 The embodiment shown is described below in detail. Figure 5 The embodiment shown is Figure 4 The differences and similarities between the illustrated embodiments are not described in detail.

[0068] like Figure 5 As shown, in an embodiment of the present application, determining the sound leakage signal corresponding to the inspection frequency of the earphone includes the following steps.

[0069] Step S451 : determining B wavefront inspection cross sections corresponding to the inspection frequency of the earphone based on the effective sound leakage influence distance of the earphone.

[0070] The effective sound leakage distance is specific to the environment. For example, in an office, because it's quieter and people are more sensitive to sound, the effective sound leakage distance in an office should be greater than that outdoors. For example, consider 10 meters or 20 meters.

[0071] The wavefront represents the spatial position where the wave energy arrives at a certain moment, and it is in motion. When considering the leakage signal, in addition to its relationship with frequency, it is also related to the position in physical space and the relative distance from the speaker module. Taking into account that the wavelength (for example, the wavelength of a 1000 Hz sound wave is about 34 cm) is much larger than the size of the headphone head, the geometric center of the headphone head is approximated as the origin, and the position of the speaker module is used to radiate sound waves from the origin to the far-field space. The wavefront inspection section is selected in the far-field space. That is, there is no need to inspect two points in the same wavefront, because the points at the same relative distance from the speaker module can be considered to have the same signal energy and no difference.

[0072] Step S452: for each of the B wavefront investigation sections, determine the far-field path transfer function from the main speaker to the wavefront investigation section and the far-field path transfer function from the auxiliary speaker to the wavefront investigation section at the investigation frequency.

[0073] Step S453: Acquire the sound signal of the speaker module at the examined frequency.

[0074] Step S454: Determine the sound leakage signal of the earphone corresponding to the inspection frequency based on the sound signal of the speaker module at the inspection frequency, the far-field path transfer function from the main speaker to each of the B wavefront inspection sections at the inspection frequency, and the far-field path transfer function from the auxiliary speaker to each of the B wavefront inspection sections.

[0075] For example, L represents the effective sound leakage distance of the earphone, ω a For different frequency values ​​investigated, (Rounded) represents a frequency ω in L a The corresponding wave number to be examined, c represents the speed of sound. For high-frequency sound waves, since they change rapidly, relatively more wavefronts need to be examined within L. For low-frequency sound waves, since they change slowly and can maintain a flat signal over a considerable period of time, relatively fewer wavefronts can be examined within L.

[0076] Headphones at the test frequency ω a The corresponding sound leakage signal is expressed as

[0077]

[0078] Among them, d(r b ,ω a ) indicates that the frequency ω a Next, on the wavefront b (It can be understood that the relative distance from the speaker module is r b The earphones (half a circle away from the human ear) leak sound signals. is the sound signal of the speaker module at the frequency under investigation.

[0079] The active noise reduction method for fully open headphones provided in the embodiment of the present application determines different wave numbers to be examined according to different frequencies, achieving the optimal effect with the minimum computing cost.

[0080] Figure 6 FIG. 1 is a flow chart of determining the loudspeaker signal of the speaker module according to an embodiment of the present application. Figure 3 Based on the embodiment shown Figure 6 The embodiment shown is described below in detail. Figure 6 The embodiment shown and Figure 3 The differences and similarities between the illustrated embodiments are not described in detail.

[0081] like Figure 6 As shown, in the embodiment of the present application, determining the sound signal of the speaker module includes the following steps.

[0082] Step S421: Determine the noise reduction signals of the main speaker and the auxiliary speaker.

[0083] The noise reduction signal is generated by the active noise reduction module after processing the signal acquired by the microphone module. It is used to reduce the noise impact of the ambient noise signal on the headphone wearer and is transmitted through the speaker module (main speaker and auxiliary speaker). If the ambient noise signal collected by the microphone module is x(ω), and W1(ω) and W2(ω) are the filter coefficients of the two filters corresponding to the main speaker and auxiliary speaker, respectively, the noise reduction signals of the main speaker and auxiliary speaker can be expressed as W1(ω)·x(ω) and W2(ω)·x(ω), respectively.

[0084] Step S422: Acquire the noise-independent signals of the main speaker and the auxiliary speaker.

[0085] For example, the noise-independent signal can be an audio signal such as a media audio signal or a voice call signal output by the earphones. Such a signal has no correlation with the ambient noise signal from the environment from a signal science perspective. It can be understood that the noise-independent signal is the signal transmitted by the speaker modules that the earphone wearer wants to listen to, namely the main speaker and the auxiliary speaker, which can be represented as m1(ω) and m2(ω) respectively. In other words, in addition to emitting noise-canceling waves, the fully open earphones also play functional sound signals.

[0086] Step S423 : determining a loudspeaker signal of the speaker module based on the noise reduction signals of the main speaker and the auxiliary speaker and the noise-independent signals of the main speaker and the auxiliary speaker.

[0087] The speaker module includes a main speaker and an auxiliary speaker. The speaker module's sound signal can be represented by a vector, such as As mentioned above,

[0088] The following is a complete description of the active noise reduction method for fully open headphones provided by an embodiment of the present application. Figure 7 The figure shows a working diagram of the active noise reduction method of the fully open earphone provided by an embodiment of the present application. Figure 7 As shown, 1 is the head of the fully open earphone, 2 is the geometric center position of the head of the fully open earphone, 3 is the position of the microphone module, which is used to collect environmental noise signals, 4 is the ear, and 5 is the target noise reduction position (the entrance of the ear canal). Figure 7 The speaker module of the fully open earphone provided in this embodiment includes a main speaker and an auxiliary speaker. The active noise reduction module also includes two filters, corresponding to the main speaker and the auxiliary speaker respectively. The structural position of the earphone has been determined. Next, the primary path transfer function P(ω) of the earphone is determined, and the secondary path transfer functions G1(ω) and G2(ω) of the earphone are determined. The ambient noise signal x(ω) collected by the microphone module is determined. Figure 7 , let W1(ω) and W2(ω) be the filter coefficients of the two filters respectively. Noise cancellation is achieved at the target noise reduction position (the entrance of the ear canal) in a three-dimensional spatial noise reduction manner, so that the noise entering the ear canal is reduced to a minimum. In this way, the static constraint condition is obtained, that is, the control equation of the active noise reduction module of the earphone

[0089]

[0090] After simplification, we can get for any frequency ω,

[0091] Among them, W1(ω) and W2(ω) are unknown and the characteristic parameters (filter coefficients) of the active noise reduction module need to be solved.

[0092] Next, let's look at the dynamic constraints. Minimizing the leakage energy of real-time audio playback through headphones is used as a dynamic constraint. In practice, leakage energy is often expressed as the product of the leakage signal and its conjugate signal. The leakage signal is related to frequency, as well as its position in physical space and its relative distance from the speaker module. Because the wavelength is much larger than the headphone head, the geometric center of the headphone head is approximated as the origin, serving as the location of the speaker module, and sound waves are radiated from the origin to the far field. Therefore, only a macroscopic and global examination of leakage signals at multiple frequencies and at multiple different relative distances (different locations throughout the entire sound field) is meaningful and valuable. This is equivalent to measuring it by minimizing the global leakage energy in three-dimensional space.

[0093] The dynamic constraint condition is expressed mathematically as Among them, i can take different integer values, ω i For different frequency values ​​to be investigated, k is taken from 1 to (rounded), c represents the speed of sound, L represents the effective distance of sound leakage from the earphones, Represents the frequencies ω within L i The corresponding wave number, r k Indicates the relative distance between different wavefronts and the speaker module, d(r k ,ω i ) indicates that at frequency ω i Next, on the wavefront k (It can be understood that the relative distance from the speaker module is r k The half circle away from the human ear) of the headphone leakage signal, d(r k ,ω i )·d * (r k ,ω i ) indicates that at frequency ω i Next, on the wavefront k If we examine 30 different frequency values ​​within the frequency limit of real-time audio playback in headphones, that is, i ranges from 1 to 30, ω i For the 30 frequency values ​​to be examined, if L is known, the wave number to be examined is The inner summation in the dynamic constraint refers to the mathematical expression d(r k ,ω i )·d * (r k ,ω i ) in the same ω i The K(i) wave numbers are summed up, and the outer summation refers to the summation of the inner summation values ​​under all 30 frequency values.

[0094] The following lists the headphone leakage signal at the same frequency.

[0095]

[0096] Among them, S1(r k ,ω)、S2(r k ,ω) are the main speaker and the auxiliary speaker sound to the same wave front r k The far-field path transfer function, is the sound signal of the speaker module, m1(ω) and m2(ω) are the noise-independent signals of the main speaker and the auxiliary speaker respectively, that is, the music signal or voice signal played by the main speaker and the auxiliary speaker, etc., the sound signal that the headphone wearer wants to listen to.

[0097] The optimized filter coefficients W1(ω) and W2(ω) are determined by the above static constraints (solving equations) and dynamic constraints (solving the maximum value equations), which are the characteristic parameters of the active noise reduction module. Solving the static constraints is equivalent to solving a quadratic equation. Whether W1(ω) and W2(ω) have a set of solutions or not, they are all located on the straight line. In the above, superimposing dynamic constraints is equivalent to jointly establishing a set of binary quadratic extrema related to W1(ω) and W2(ω), and the best set of W1(ω) and W2(ω) among the countless sets of solutions can be obtained.

[0098] Combined with the above Figures 1 to 7 , describes the method embodiment of the present application in detail, and the following is combined with Figure 8 and Figure 9 It should be understood that the description of the method embodiment corresponds to the description of the device embodiment, and therefore, for parts not described in detail, reference can be made to the previous method embodiment.

[0099] Figure 8 The figure shows a schematic diagram of the structure of the functional device of the fully open earphone provided by an embodiment of the present application. Figure 8 As shown, the functional device of the fully open earphones provided in the embodiment of the present application includes a microphone module 10, a speaker module 20, and an active noise reduction module 30. Specifically, the microphone module 10 includes at least one microphone for collecting ambient noise signals; the speaker module 20 includes a main speaker and an auxiliary speaker for transmitting noise-independent signals and also for transmitting noise reduction signals to reduce the noise impact of ambient noise signals on the wearer of the earphones; the characteristic parameters of the active noise reduction module 30 are determined based on the methods described above in this specification according to various embodiments of the present application.

[0100] Exemplarily, the microphone module 10 includes multiple microphones, and the signals collected by the multiple microphones can be averaged as the collected ambient noise signal.

[0101] In some embodiments, the fully-open headphones provided include a main speaker and an auxiliary speaker. During the design stage of the fully-open headphones, after the specific structure of the headphones is determined, the primary path and the secondary path are determined. Based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker, the characteristic parameters of the active noise reduction module are determined, so that such fully-open headphones have good noise reduction effect and high quality.

[0102] In some embodiments, the characteristic parameters of the active noise reduction module of the fully open headphones are determined as follows: based on the sound leakage energy of the real-time audio played by the headphones, a dynamic constraint is determined; based on the static constraint and the dynamic constraint, the characteristic parameters of the active noise reduction module are determined; wherein the expression of the static constraint is determined by the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker. The fully open headphones provided in this embodiment of the application include a main speaker and an auxiliary speaker, and adopt dynamic constraints to minimize the sound leakage energy, improve the obvious sound leakage phenomenon of the fully open headphones, suppress the interference of the headphone leakage to the environment to the minimum, and enhance the experience of people around the headphone wearer.

[0103] In some embodiments, the fully open earphones further include a fixing device connected to the functional device, the fixing device being used to fix the earphones to the ear of the earphone wearer and to make the head of the earphones adhere to the auricle, presenting a completely out-of-ear style. Exemplarily, the head of the earphones includes the functional device. Adhering to the auricle means that the auricle is not subjected to force and does not provide support or fixation for the head of the earphones. In addition, the head of the earphones can also be connected to the auricle only through the fixing device, and the head of the earphones can be suspended in the air and not in contact with the auricle.

[0104] Simply shifting the wearing position of in-ear headphones outward is undoubtedly user-friendly. However, when wearing fully open headphones, the ear canal opening is not sealed, creating an open sound field between the headphones and the ear. Existing headphone solutions make it nearly impossible to deploy active noise reduction, and the amount of sound leakage from the headphones significantly impacts those around you.

[0105] In some embodiments, the fully open earphones include functional devices, which include: a microphone module, including at least one microphone, for collecting ambient noise signals; a speaker module, including a main speaker and an auxiliary speaker, for transmitting noise-independent signals and also for transmitting noise reduction signals to reduce the noise impact of ambient noise signals on the earphone wearer; an active noise reduction module, wherein the characteristic parameters of the active noise reduction module are determined based on the following method: determining the primary path transfer function based on the position of the microphone module and the target noise reduction position, wherein the target noise reduction position covers the ear canal entrance position; determining the secondary path transfer function of the main speaker based on the position of the main speaker and the target noise reduction position; determining the secondary path transfer function of the auxiliary speaker based on the position of the auxiliary speaker and the target noise reduction position; determining the characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker and the secondary path transfer function of the auxiliary speaker. Among them, based on the primary path transfer function, the secondary path transfer function of the main speaker and the secondary path transfer function of the auxiliary speaker, the characteristic parameters of the active noise reduction module are determined, including: based on the sound leakage energy of the real-time audio playback of the headphones, the dynamic constraint conditions are determined; based on the static constraint conditions and the dynamic constraint conditions, the characteristic parameters of the active noise reduction module are determined; wherein, the expression of the static constraint conditions is determined by the primary path transfer function, the secondary path transfer function of the main speaker and the secondary path transfer function of the auxiliary speaker. The fully open headphones provided in the embodiment of the present application include a main speaker and an auxiliary speaker, and the characteristic parameters of the active noise reduction module are determined based on the above method. In a three-dimensional spatial noise reduction manner, while improving wearing comfort and protecting the hearing of the headphone user (the advantages of existing non-in-ear headphones), the active noise reduction effect is guaranteed and the impact on the surrounding people (the pain point of existing non-in-ear headphones) is avoided, thereby comprehensively improving the quality of the fully open headphones.

[0106] In some embodiments, the securing device includes an ear hook module that is configured to connect to the base of the ear of the wearer, allowing the earphone to be hooked to the wearer's ear to secure the earphone. For example, the earphone can be hooked to the outer concha to secure the earphone. Furthermore, the securing device may also take the form of an ear clip or other similar device, which is not specifically limited here. By hooking the earphone to the wearer's ear to secure the earphone, the earphone head does not need to be inserted into the ear for securement, thereby improving wearing comfort. Figure 9 The figure shows a wearing diagram of a fully open headset provided by an embodiment of the present application. Figure 9 As shown, 1 is the head of the fully open headset, 4 is the ear, and 6 is the ear-hanging module.

[0107] In some embodiments, a sound outlet is provided on the head of the earphone, wherein the sound outlet is arranged facing the entrance of the ear canal of the earphone wearer, and the central axis of the auxiliary speaker is non-parallel to the central axis of the main speaker. It can be understood that the auxiliary speaker is not arranged directly opposite or back to back to the main speaker. If the central axis of the auxiliary speaker is arranged parallel to the central axis of the main speaker, the auxiliary speaker's ability to interfere with the main speaker's sound leakage to the far end is the weakest at this time, while when it is non-parallel, the auxiliary speaker's ability to interfere with the sound leakage to the far end is enhanced, so that the energy is concentrated toward the axis of the sound outlet. The fully-open earphones provided in the embodiments of the present application not only protect the wearer's hearing and improve the noise reduction performance of the earphones, but also improve the sound leakage effect of the fully-open earphones.

[0108] This application does not specifically limit the number of sound holes. In some embodiments, a fully open headphone has a single sound hole, meaning that two speakers share one sound hole. Alternatively, a fully open headphone has two separate sound holes for each speaker. The two sound holes can be located on the same side of the ear, facing away from each other, or one of the sound holes can be located on the side of the headphone head. This application does not specifically limit the orientation of the sound holes.

[0109] In some embodiments, the fully open earphones further include a communication device, such as a communication module with Bluetooth or infrared signal transmission capabilities. In other words, the fully open earphones and active noise reduction methods provided in the embodiments of the present application can be applied to wireless Bluetooth earphones.

[0110] In some embodiments, the fully open earphones are designed for monaural use.

[0111] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0112] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0113] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0114] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0115] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An active noise reduction method for fully open headphones, characterized in that: The fully open headset includes a microphone module, a speaker module and an active noise reduction module, and the speaker module includes a main speaker and an auxiliary speaker; The method comprises: determining a primary path transfer function based on a position of the microphone module and a target noise reduction position, wherein the target noise reduction position covers an ear canal entrance position; determining a secondary path transfer function of the main speaker based on the position of the main speaker and the target noise reduction position; determining a secondary path transfer function of the auxiliary speaker based on the position of the auxiliary speaker and the target noise reduction position; determining characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the primary speaker, and the secondary path transfer function of the auxiliary speaker; The determining of the characteristic parameters of the active noise reduction module based on the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker includes: Minimizing the sound leakage energy of the earphones playing audio in real time is determined as a dynamic constraint condition; wherein, the sound leakage energy characterizes the sound leakage effect of the speaker module relative to people other than the earphone wearer; based on the static constraint conditions and the dynamic constraint conditions, the characteristic parameters of the active noise reduction module are determined; wherein, the expression of the static constraint condition is determined by the primary path transfer function, the secondary path transfer function of the main speaker, and the secondary path transfer function of the auxiliary speaker.

2. The active noise reduction method according to claim 1, characterized in that: Before determining the dynamic constraint condition based on the sound leakage energy of the real-time audio played by the earphone, the method further includes: calling a far-field transfer function of the speaker module; Determining a speaker signal of the speaker module; Based on the far-field transfer function of the speaker module and the sound signal of the speaker module, the sound leakage energy of the real-time audio played by the earphone is determined.

3. The active noise reduction method according to claim 1, wherein: Before determining the dynamic constraint condition based on the sound leakage energy of the real-time audio played by the earphone, the method further includes: Determining A inspection frequencies based on a frequency limit and a spectral density of the real-time audio played by the headset; For each of the A inspection frequencies, determining a sound leakage signal corresponding to the headset at the inspection frequency; The energies of the leakage sound signals corresponding to the A inspection frequencies are added together to determine the leakage sound energy of the audio played in real time by the earphone.

4. The active noise reduction method according to claim 3, characterized in that: Determining the sound leakage signal corresponding to the headset at the inspection frequency includes: Determining B wavefront inspection cross sections of the earphone corresponding to the inspection frequency based on the effective sound leakage impact distance of the earphone; For each of the B wavefront investigation sections, determining a far-field path transfer function from the sound emitted by the main speaker to the wavefront investigation section and a far-field path transfer function from the sound emitted by the auxiliary speaker to the wavefront investigation section at the investigation frequency; Acquire a sound signal of the speaker module at the inspection frequency; Based on the sound signal of the speaker module at the investigation frequency, the far-field path transfer function from the main speaker to each of the B wavefront investigation sections at the investigation frequency, and the far-field path transfer function from the auxiliary speaker to each of the B wavefront investigation sections, the sound leakage signal corresponding to the earphone at the investigation frequency is determined.

5. The active noise reduction method according to claim 2, characterized in that: The determining the loudspeaker signal of the loudspeaker module includes: determining respective noise reduction signals of the main speaker and the auxiliary speaker; Acquire noise-independent signals of the main speaker and the auxiliary speaker; A sound signal of the speaker module is determined based on the noise reduction signals of the main speaker and the auxiliary speaker and the noise-independent signals of the main speaker and the auxiliary speaker.

6. A fully open earphone, characterized in that: The earphone includes a functional device, and the functional device includes: A microphone module includes at least one microphone for collecting ambient noise signals; The speaker module includes a main speaker and an auxiliary speaker, which are used to transmit noise-independent signals and noise reduction signals to reduce the noise impact of the ambient noise signal on the headphone wearer; An active noise reduction module, wherein characteristic parameters of the active noise reduction module are determined based on the method according to any one of claims 1 to 5.

7. The fully open earphone according to claim 6, characterized in that It also includes a fixing device connected to the functional device, which is used to fix the earphone to the ear of the earphone wearer and make the head of the earphone stick to the external auricle, presenting a completely non-in-ear style.

8. The fully open earphone according to claim 7, characterized in that: The fixing device includes an ear-hanging module, which is used to be connected to the base of the ear of the headphone wearer so as to hang the headphone on the ear of the headphone wearer to fix the headphone.

9. The fully open earphone according to any one of claims 6 to 8, characterized in that: The head of the earphone is provided with a sound outlet, wherein the sound outlet is arranged facing the entrance of the ear canal of the earphone wearer, and the central axis of the auxiliary speaker is arranged non-parallel to the central axis of the main speaker.

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