System, audio wearable device, and method for evaluating the fit quality of headphones

Abstract

Systems, devices, and methods for evaluating the fit quality of headphones when used in a noisy environment. The headphones have an external microphone for capturing outer ear audio signals and an internal microphone for capturing inner ear audio signals. The fit quality is estimated by estimating a filter based on the captured inner and outer ear audio signals, and determining the fit quality based on identified coefficients of the estimated filter. Systems, devices, and methods for evaluating the seal quality of headphones when used in a quiet environment. The headphones have a speaker for transmitting sound stimuli to the ear canal and an internal microphone for capturing audio signals within the ear canal. The seal quality is evaluated by estimating a transfer function based on the transmitted and captured sound stimuli, and determining at least one seal quality indicator based on the signal amplitude of the transfer function.

Description

[0001] This invention application is a divisional application of the invention application filed by the present applicant on June 26, 2018, with application number 201880054791.2 and invention name “System, audio wearable device and method for evaluating the fitting quality of headphones”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 524,873, filed in the U.S. Patent and Trademark Office on June 26, 2017, and entitled “System and Method of Continuous Assessment of a Fit of an In-Ear Wearable Device Using Digital Adaptive Filters.” Technical Field

[0004] The present invention generally relates to systems, devices, and methods for evaluating the fit quality of headphones, and more particularly to systems, devices, and methods for evaluating the fit quality of headphones in noisy or silent environments. Background of the Invention

[0005] Headphones are used in a variety of applications. For example, headphones can be passive hearing protection devices (HPDs) used to protect the wearer's hearing from ambient noise or sound. In another case, headphones can be communication devices, for example, used to allow two or more people to communicate in a noisy environment. Headphones are well known in the art. However, such devices are only effective if they are worn properly to provide a good fit. This is particularly true for in-ear or in-ear devices such as earplugs, external ear protectors, or communication devices. In the case of in-ear devices, the headphones must be correctly and carefully inserted into the ear canal to adequately protect the wearer's hearing or allow for proper communication. In the case of external ear protectors or communication devices, the headphones must properly cover and seal the ear cup to adequately protect the wearer's hearing or allow for proper communication. Moreover, in most cases, headphones must have a shape and size that adequately fits the wearer's ear or ear canal. Furthermore, the fit of headphones can deteriorate over time when worn for extended periods of time, as the headphones can shift position, loosen, or deform over time. Furthermore, the materials used in headphones can degrade over time, affecting their fit. The fit quality of the earphones degrades only gradually, often unnoticed by the wearer. For example, in the case of earplugs, the wearer cannot detect a loosening of the earplug assembly because their hearing naturally adapts to the gradually increasing noise entering the earphones. Over the years, various "fit test" solutions using different "fit test" systems have been developed for earphones to address this issue, thereby ensuring proper fit quality and providing the desired sound attenuation.

[0006] This standalone "fit test" solution often offers great potential and advantages for hearing protection. However, the measurements performed only provide a "snapshot" of the sound attenuation provided by the earphones at the time of measurement. Research has shown that earplugs do not always fit consistently and can become loose when worn for extended periods, necessitating regular repositioning. However, wearers often overlook the need to regularly reposition their earplugs. In reality, wearers are largely preoccupied with their tasks, and pausing to reposition their earplugs can be a burden, particularly for workers who need to remove body coverings (such as masks or gloves) or wash their hands or leave their work environment to reposition their earplugs. Furthermore, wearers often forget to reposition their earplugs because they are unaware that their attenuation levels are decreasing. For workers, regularly leaving their work environment to perform separate fit tests in order to regularly assess the fit quality of their earplugs while wearing them can be a significant burden and hassle. In reality, standalone "fit test" solutions are often time-consuming and challenging to manage.

[0007] Another issue relates to the fact that measurements obtained with fit test solutions, like any metrological device, have inherent uncertainty—the reported attenuation value may differ from the "true" physical attenuation. This uncertainty should be reported or otherwise accounted for by the fit test system so that operators can take it into account, particularly in applications requiring specific HPD noise attenuation. Several third-party independent validation studies have been conducted on existing commercial systems. Some studies have reported that certain existing fit test systems can produce significantly different results from sound attenuation measurements of the same individual following standardized procedures (e.g., Real Ear Threshold Attenuation (REAT) measurements as specified in ISO 4869 or ANSI / ASA S12.6). This uncertainty can be significantly reduced by removing two major uncertainty components. One of these is so-called "fit uncertainty," which relates to the variability of fitting / refitting a given headphone to a user over time. The other, often referred to as "spectral uncertainty," results from measuring sound attenuation only within a given noise spectrum, rather than within the ambient noise to which the user is actually exposed. Therefore, there is a need for a solution that can seamlessly evaluate the fit quality of headphones with sufficient accuracy when worn in the user's work environment. Technologies and methods for objective evaluation of the acoustic performance of in-ear devices have been disclosed in U.S. Patents Nos. 7,688,983, 8,254,586 and 8,254,587. The technology uses the F-MIRE (Field Microphone in Real Ear) method. The F-MIRE method simultaneously measures the sound pressure level in the ear canal below the hearing protector (in-ear microphone) and outside the hearing protector (external ear microphone), and the difference between these two measurements allows the attenuation level of the hearing protector to be estimated. This method requires the calculation of several Fast Fourier Transforms (FFTs), either for calculating the automatic spectrum of the in-ear microphone and the external ear microphone (U.S. Patent No. 6,687,377), or for calculating transfer function estimates using the above-mentioned automatic spectrum and cross-spectrum (U.S. Patent No. 7,688,983).

[0008] The F-MIRE method, as disclosed in U.S. Patent Nos. 6,687,377 and 7,688,983, is computationally demanding and is limited to instantaneous assessment of the attenuation provided by the HPD, and has no ability to verify or ensure that the assessed attenuation is provided during subsequent hours, days, weeks, etc. of wear of the HPD.

[0009] Other technologies, such as the method disclosed in U.S. Patent No. 6,567,524, provide in-ear wearable audio devices that protect the ear while allowing communication / conversation in noisy environments. These technologies typically use electroacoustic methods to assess the proper fit of audio in-ear wearable devices. This method uses an internal microspeaker to link the playback sound level with the same sound level actually measured by an in-ear microphone. This relationship is measured based on amplitude and phase at different discrete frequencies and compared to predetermined reference values that represent a properly sealed earphone. However, this method requires a calibration step to be performed before assessing the seal quality. If the earphone is moved between the calibration step and the assessment step, the assessed seal quality may be inaccurate. Furthermore, since a separate calibration step must be performed beforehand, the seal quality assessment is not provided seamlessly. Therefore, a solution is needed to provide an assessment of fit quality or seal quality that is seamless for the user, does not rely on intensive computation, and can operate in real time while the earphone is in use, without requiring the user to leave their environment and without requiring a separate calibration step. Summary of the Invention

[0010] The shortcomings of the prior art are generally alleviated by providing a system, apparatus, and method for seamlessly evaluating the fit quality or seal quality of an earphone to determine an indicator of the level of sound attenuation provided by the earphone when worn and in use

[0011] It should be appreciated that the earphones may be any type of HPD, such as earplugs, hearing aids (prostheses), upper or outer ear protection devices, or headphones (in-ear audio wearable devices) to protect the ears, allow communication / conversation in a noisy environment, or capture biosignals (heartbeat or breathing rate) present in a closed ear canal. Such earphones are effective and provide the desired sound attenuation if the fit and seal quality of the earphones are adequate when used.

[0012] Those skilled in the art will recognize that the quality of the fit or seal can be affected by the shape, size, position, integrity, degradation, and pre-insertion procedures of the earphone. The fit and seal quality can also be affected by various movements of the ear canal wall. In fact, when a user makes jaw movements, such as talking, yawning, or eating, the ear canal wall can move and affect the position or shape of the earphone.

[0013] It should be understood that the term microphone used herein refers to any type of sound capturing device or apparatus for capturing sound. Additionally, the term loudspeaker and / or speaker refers to any type of sound generating device or any apparatus for reproducing sound from a sound source.

[0014] Fit quality in noisy environments

[0015] According to one aspect, an audio wearable device is provided, which has headphones that are operable to prevent ambient sound from entering the user's ear canal. The headphones have an external microphone for capturing external ear audio signals outside the ear canal and an internal microphone for capturing inner ear audio signals inside the ear canal. The audio wearable device has a modeling module, a coefficient identifier, and a fitting quality assessor. The modeling module is adapted to estimate an attenuation model of the headphones when used in a noisy environment based on the captured external ear audio signals and the captured inner ear audio signals. Note that the attenuation model represents an acoustic filter. The coefficient identifier is adapted to identify a set of acoustic filter coefficients based on the attenuation model. The fitting quality assessor is adapted to analyze the set of acoustic filter coefficients and determine at least one fitting quality indicator based on the analysis. The identified filter coefficients include at least one hundred coefficients at a sampling rate of approximately 8 kHz. The set of filter coefficients includes at least one hundred and fifty coefficients.

[0016] According to another aspect, a fit quality assessment system for headphones is provided. The headphones are configured to prevent ambient noise from entering a wearer's ear canal and include an external microphone for capturing outer ear audio signals outside the ear canal and an internal microphone for capturing inner ear audio signals inside the ear canal. The system includes a first receiver, a second receiver, a modeling module, a coefficient identifier, a fit quality assessor, and a fit quality communication module. The first receiver is adapted to receive the captured outer ear audio signals. The second receiver is adapted to receive the captured inner ear audio signals. The modeling module is adapted to connect to the first and second receivers and estimate an acoustic filter based on the captured outer ear audio signals and the captured inner ear audio signals. The acoustic filter represents the attenuation provided by the headphones when used in a noisy environment. The coefficient identifier is adapted to identify a set of filter coefficients based on the estimated acoustic filter. The fit quality assessor is adapted to analyze the set of filter coefficients and determine at least one fit quality indicator based on the analysis. The fit quality communication module is adapted to transmit status information indicating the fit quality indicator. The fit quality assessor also includes an averaging module adapted to calculate an average of the frequency responses, each of which is associated with at least one of the multiple sets of filter coefficients. The fit quality evaluator further comprises a frequency response extractor adapted to calculate a frequency response over a predetermined frequency band group based on the acoustic filter coefficients. The predetermined frequency band group is within a range of 150 Hz and 350 Hz.

[0017] According to another aspect, a method for evaluating the fit quality of headphones is provided. The headphones are configured to prevent ambient noise from entering the wearer's ear canal. The headphones may include an external microphone for capturing external ear sound signals outside the ear canal and an internal microphone for capturing inner ear sound signals inside the ear canal. The method includes capturing the inner ear sound signal and / or receiving the external ear sound signal, estimating a digital filter, identifying multiple coefficients, and determining the fit quality. The inner ear sound signal may be received from the internal microphone. The external ear sound signal may be received from the external microphone. Note that the received external ear sound signal represents a noisy environment. The digital filter is estimated based on the received inner ear sound signal and the received external ear sound signal. The identified coefficients are the coefficients of the estimated filter. The fit quality is determined based on the identified coefficients. The fit quality can be determined based on the reliability of the filter.

[0018] According to another aspect, a fit quality assessment system for headphones is provided. The headphones are configured to prevent ambient noise from entering a wearer's ear canal, and include an external microphone for capturing outer ear audio signals outside the ear canal and an internal microphone for capturing inner ear audio signals inside the ear canal. The system includes a first receiver adapted to receive the captured outer ear audio signals, a second receiver adapted to receive the captured inner ear audio signals, a modeling module configured to connect to the first and second receivers and estimate a filter representing attenuation provided by the headphones when used in a noisy environment, the filter estimated based on the captured outer ear audio signals and the captured inner ear audio signals, a coefficient identifier configured to identify a set of filter coefficients based on the estimated filters, a fit quality assessor configured to analyze the set of filter coefficients and determine at least one fit quality metric based on the analysis, and a fit quality communication module configured to display status information representing the fit quality metric. The fit quality assessment system also includes a frequency response extractor configured to calculate a frequency response over a predetermined range of a frequency band based on the set of filter coefficients. The fit quality assessor further comprises a fit quality determiner adapted to determine a fit quality indicator based on the comparison and the calculation. A fit quality communication module adapted to be connected to a speaker of the headset and adapted to transmit the status information to the speaker. The fit quality communication module is configured to transmit the status information to a monitoring module of the system.

[0019] Fit quality in quiet environments

[0020] According to one aspect, a wearable audio device including an earphone is provided. The earphone is operable to prevent ambient sound from entering a user's ear canal. The earphone includes a sound emitting device, such as a speaker, for emitting sound into the ear canal and a sound capturing device, such as an internal microphone, for capturing inner ear audio signals within the ear canal. The wearable audio device includes a sound source generator, a sound source emitter, a modeling module, a signal amplitude identifier, and a seal quality evaluator. The sound source generator is configured to generate sound stimuli at a predetermined seal evaluation frequency. The sound source emitter is configured to transmit the sound stimuli to the speaker and the modeling module. The modeling module is configured to estimate a transfer function of the earphone for use in a quiet environment based on a comparison of the sound stimuli with inner ear audio signals of the sound stimuli captured by the internal microphone. The signal amplitude identifier is configured to establish a signal amplitude of the transfer function at a predetermined seal evaluation frequency. The seal quality evaluator is configured to determine at least one seal quality indicator based on the signal amplitude. The predetermined seal evaluation frequency may be between approximately 100 Hz and approximately 200 Hz. The predetermined seal evaluation frequency may be between approximately 2000 Hz and approximately 5000 Hz. The sound source generator may be configured to generate sound stimuli at a plurality of predetermined seal assessment frequencies. The signal amplitude identifier may be further configured to establish a plurality of signal amplitudes based on the transfer function and the plurality of predetermined seal assessment frequencies, and the seal quality assessor may be adapted to determine at least one seal quality indicator based on the plurality of signal amplitudes. The sound source generator may also be adapted to generate a plurality of sound stimuli at a plurality of predetermined otoacoustic emission measurement calibration frequencies. The predetermined seal assessment frequency is one of the plurality of otoacoustic emission measurement calibration frequencies. The plurality of sound stimuli may include two pure tone frequencies. The device further includes a seal quality communication module adapted to transmit status information representing the at least one seal quality indicator. The status information is transmitted to the sound emitting device or the monitoring system. The at least one seal quality indicator may be a leak indicator selected from the group consisting of a leak radius size, a leak length, and a leak amount. The sound emitting device may be a speaker. The sound capturing device may be an internal microphone.

[0021] According to another aspect, a seal quality assessment system for earphones is provided. The earphones are configured to prevent ambient noise from entering the wearer's ear canal. The earphones include a sound emitting device, such as a speaker, for emitting sound into the ear canal and a sound capturing device, such as an internal microphone, for capturing inner ear audio signals within the ear canal. The seal quality assessment system includes a sound source generator, a sound source transmitter, a receiver, a modeling module, a signal amplitude identifier, and a seal quality assessor. The sound source generator is configured to generate sound stimuli at a predetermined seal assessment frequency. The sound source transmitter is configured to transmit the sound stimuli to the speaker and the modeling module. The receiver is configured to receive inner ear audio signals of the sound stimuli captured by the internal microphone. The modeling module is configured to estimate the transfer function of the earphones when used in a quiet environment based on a comparison of the sound stimuli and the received inner ear audio signals. The signal amplitude identifier is configured to establish a signal amplitude of the transfer function at a predetermined seal assessment frequency. The seal quality assessor is configured to determine at least one seal quality indicator based on the signal amplitude. The predetermined seal assessment frequency may be between approximately 100 Hz and approximately 200 Hz. The predetermined seal assessment frequency may be between approximately 2000 Hz and approximately 5000 Hz. The sound source generator may be configured to generate sound stimuli at a plurality of predetermined seal assessment frequencies. The signal amplitude identifier may be further configured to establish a plurality of signal amplitudes based on the transfer function and the plurality of predetermined seal assessment frequencies, and the seal quality assessor may be adapted to determine at least one seal quality indicator based on the plurality of signal amplitudes. The sound source generator may also be adapted to generate a plurality of sound stimuli at a plurality of predetermined otoacoustic emission measurement calibration frequencies. The predetermined seal assessment frequency is one of the plurality of otoacoustic emission measurement calibration frequencies. The plurality of sound stimuli may include two pure tone frequencies. The device may further include a seal quality communication module adapted to transmit status information representing the at least one seal quality indicator. The status information may be transmitted to the sound emitting device or the monitoring system. The at least one seal quality indicator may be a leak indicator selected from the group consisting of a leak radius size, a leak length, and a leak amount. The sound emitting device may be a speaker. The sound capturing device may be an internal microphone.

[0022] According to yet another aspect, a method for evaluating the seal quality of an earphone is provided. The earphone is configured to prevent ambient noise from entering a wearer's ear canal. For example, the earphone may include a speaker for emitting sound into the ear canal and / or an internal microphone for capturing inner ear audio signals within the ear canal. The method for evaluating the seal quality includes generating a sound stimulus, emitting the sound stimulus, capturing inner ear audio signals, comparing multiple generated sound stimuli, estimating a transfer function, identifying signal amplitudes, and determining at least one seal quality indicator. The sound stimulus is generated at a predetermined seal evaluation frequency. The sound stimulus is emitted into the ear canal. The received inner ear audio signal is the inner ear audio signal of the sound stimulus captured by the internal microphone. The generated sound stimulus is compared with the received inner ear audio signal. The transfer function is estimated based on the comparison. The identified signal amplitude is the signal amplitude of the transfer function at the predetermined seal evaluation frequency. The at least one seal quality indicator is determined based on the signal amplitude. The at least one seal quality indicator may be determined based on a data set of previously measured seal quality indicators. The sound stimulus may be generated at multiple predetermined seal evaluation frequencies. Multiple signal amplitudes may be identified based on the transfer function and the multiple predetermined seal evaluation frequencies. Multiple sound stimuli may be generated at multiple predetermined otoacoustic emission measurement calibration frequencies. The plurality of sound stimuli includes two pure tone frequencies. Status information representing the at least one seal quality indicator may be sent. The status information may be sent to a monitoring device.

[0023] Other and further aspects and advantages of the present invention will become apparent upon understanding of the exemplary embodiments to be described or will be pointed out in the appended claims, and various advantages not mentioned herein will occur to those skilled in the art upon practicing the invention.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other aspects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1A is an illustration of an embodiment of an audio wearable device having an earphone placed in the entrance of a wearer's ear canal, the earphone having an outer ear microphone and an inner ear microphone for evaluating the fit quality of the earphone when worn in a noisy environment;

[0027] Figure 1B According to one embodiment Figure 1A A block diagram of components of an audio wearable device including a modeling module and a fit quality evaluator;

[0028] Figure 1C According to another embodiment Figure 1AA block diagram of components of an audio wearable device, the device including a modeling module, a fitting quality evaluator, and an interference detector;

[0029] Figure 1D According to one embodiment Figure 1B and 1C A block diagram of the components of the modeling module;

[0030] Figure 2A According to one embodiment Figure 1B and 1C a block diagram of components of a fit quality evaluator having a coefficient analyzer and a fit quality determiner;

[0031] Figure 2B According to another embodiment Figure 1B and 1C a block diagram of components of a fit quality evaluator having a response extractor and a fit quality determiner;

[0032] Figure 2C According to another embodiment Figure 1B and 1C a block diagram of components of a fit quality evaluator having a coefficient analyzer, a response extractor, and a fit quality determiner;

[0033] Figure 3A According to one embodiment Figure 2A and 2C A block diagram of components of a coefficient analyzer having a threshold envelope analyzer and an averaging module;

[0034] Figure 3B According to one embodiment Figure 2B and 2C A block diagram of components of a response extractor having a response calculator and an averaging module;

[0035] Figure 3C is Figure 2B and 2C Illustration of the lower bad fit limit and the upper good fit limit used by the fit quality determiner;

[0036] Figure 3D is a block diagram of components of a fit quality assessment system having a fit assessment module and a communication module according to one embodiment;

[0037] Figure 4A is a block diagram of a method for determining a fit quality indicator according to one embodiment;

[0038] Figure 4Bis a block diagram of a method for determining a fit quality indicator by verifying filter accuracy according to an alternative embodiment;

[0039] Figure 4C According to an alternative embodiment, the coefficients are determined by analyzing Figure 4A and 4B Block diagram of the method for fitting quality indicators;

[0040] Figure 4D is according to an alternative embodiment for determining by extracting the response Figure 4A and 4B Block diagram of the method for fitting quality indicators;

[0041] Figure 4E is a method according to an alternative embodiment for determining by analyzing the coefficients and extracting the response Figure 4A and 4B Block diagram of the method for fitting quality indicators;

[0042] Figure 4F is a block diagram of a method for evaluating fit quality, the method including determining a fit quality indicator and transmitting the fit quality indicator.

[0043] Figure 5A is a flow chart of a method for evaluating the fit quality of headphones by determining whether filter coefficients are within a predetermined coefficient envelope according to one embodiment;

[0044] Figure 5B According to one embodiment, Figure 5A a plot of the envelope of predetermined coefficients used by the method;

[0045] Figure 5C is a flow chart of a method for evaluating the fitting quality of headphones by extracting frequency responses at various predetermined frequencies according to one embodiment;

[0046] Figure 5D is an illustration of a system for evaluating the fit quality of headphones using a digital adaptive filter in a quiet environment, according to one embodiment;

[0047] Figure 6A is an illustration of an audio wearable device having an earphone placed in the entrance of a wearer's ear canal, the earphone having a speaker and an inner ear microphone for evaluating the fit quality of the earphone when worn in a quiet environment, according to one embodiment;

[0048] Figure 6B yes Figure 6A A block diagram of components of an audio wearable device having a modeling module and a seal quality evaluator according to one embodiment;

[0049] Figure 6C yes Figure 6B A block diagram of components of a seal quality evaluator having a signal amplitude identifier and a seal quality determiner according to one embodiment;

[0050] Figure 6D According to one embodiment, Figure 6C Illustration of a lookup table used by a seal quality determiner;

[0051] Figure 6E is a block diagram of components of a seal quality assessment system having a seal assessment module and a communication module according to one embodiment;

[0052] Figure 7A is a block diagram of a method for estimating the fit quality of a headset having a loudspeaker and an inner-ear microphone by estimating a transfer function from a stimulus generated by the loudspeaker and an audio signal captured by the inner-ear microphone when in a quiet environment, according to one embodiment;

[0053] Figure 7B According to one embodiment, the excitation signal is compared with the captured audio signal and the convergence comparison is used to estimate Figure 7A Block diagram of the transfer function method;

[0054] Figure 7C According to one embodiment, the signal amplitude is determined by establishing the seal evaluation frequency Figure 7A A block diagram of the method for the seal quality index;

[0055] Figure 7D is a block diagram of a method for providing otoacoustic measurements after evaluating the seal quality of an earphone according to one embodiment;

[0056] Figure 7E is a block diagram of a method for evaluating seal quality, the method including determining a seal quality indicator and transmitting the seal quality indicator.

[0057] Figure 8 is a graph showing various transfer functions according to one embodiment, each transfer function corresponding to a different seal quality indicator;

[0058] Figure 9 is a graph showing an example of a magnitude response calculated based on coefficients of an adaptive filter according to one embodiment;

[0059] Figure 10 is a graph representing passive attenuation provided by headphones on 24 participants according to one embodiment and arbitrarily corresponding to a poor fit or a good fit;

[0060] Figure 11 and 12is a graph showing a linear regression of passive attenuation (dB) as a function of fit test value (dB) according to one embodiment;

[0061] Figure 13 is a graph showing a linear regression of personal attenuation level (dB) as a function of fitted test value (dB) when in a quiet environment according to one embodiment; and

[0062] Figure 14 is an illustration of an audio wearable device with an earphone placed in the entrance of a wearer's ear canal, the earphone having an outer ear microphone, an inner ear microphone, and a speaker for evaluating the fit quality of the earphone when worn in a noisy environment or a quiet environment, according to one embodiment.

[0063] Detailed description of specific embodiments

[0064] The following describes a system, apparatus, and method for evaluating the fit quality of headphones. Although the system, apparatus, and method are described in terms of specific exemplary embodiments, it should be understood that the embodiments described herein are merely exemplary and the scope of the apparatus and method is not intended to be limited thereby.

[0065] For example, it will be appreciated that fit quality can indicate earpiece position, seal, shape, deformation, degradation, integrity, porosity, etc.

[0066] Fit quality in noisy environments

[0067] First reference Figure 1A , there is an embodiment of an apparatus 100 for evaluating the fit quality of earphones 102. Apparatus 100 includes earphones 102, such as, but not limited to, earbuds, in-the-ear devices, or any other type of device suitable for preventing sound or noise from entering the ear canal 12 of a user's ear 10. Earphones 102 also include an external microphone (OEM) 104 and an internal microphone (IEM) 106, which are positioned and oriented to capture sound outside and inside the ear canal, respectively. In effect, earphones 102 act as a sound barrier between external microphone 104 and internal microphone 106.

[0068] In more detail, the external microphone (OEM) 104 is adapted to capture outer ear audio signals, such as sounds or noises outside the ear 10 or outside the ear canal 12, depending on the type of earphone 102. Depending on the type of earphone 102, the internal microphone (IEM) 106 is adapted to capture inner ear audio signals, such as sounds or noises, inside the ear canal 12 or (in the ear canal) below or behind the earphone 102. According to one embodiment, the outer ear audio signals and the inner ear audio signals are captured simultaneously in the presence of ambient noise.

[0069] The signals captured by the external microphone 104 and the internal microphone 106 are fed to the modeling module 110 (e.g. Figure 1B ), in order to determine the attenuation model of the earphone 102 when in use (ie, when it is worn by the user). The modeling module 110 is adapted to determine the attenuation model of the earphone 102 based on the captured outer ear signal and the captured inner ear signal.

[0070] According to one embodiment, the modeling module 110 is adapted to estimate the contribution of the outer ear audio signal within the ear canal based on the captured inner ear audio signal and the captured outer ear audio signal. The contribution of the outer ear audio signal within the ear canal is iteratively estimated by attempting to reduce the difference between the captured inner ear audio signal and the estimated contribution of the outer ear audio signal within the ear canal. The estimated contribution of the outer ear audio signal within the ear canal represents an attenuation model of the earphone when in use.

[0071] According to one embodiment, the attenuation model of the earphones is characterized by a filter, and the modeling module is further adapted to determine the coefficients of the filter.

[0072] Based on the determined filter coefficients, the fit quality evaluator 120 of the apparatus 100 is adapted to analyze the coefficients and determine at least one fit quality indicator based on the analysis. The fit quality evaluator 120 indicates whether the earphone 102 is properly fitted to the user's ear 10 in an environment generating noise, whether periodic or continuous, such as industrial noise. In one embodiment, a well-fitting earphone 102 has filter coefficients within a predetermined matching envelope, or the average value of the frequency response in a particular frequency band is identified as being above or below a predetermined level.

[0073] It should be appreciated that the audio wearable device 100 can be adapted to evaluate the fit quality of the earphones in real time or with some delay while the inner ear and outer ear audio signals are being captured. Furthermore, the audio wearable device 100 can be adapted to provide the fit quality based on previously captured and recorded inner ear audio signals and outer ear audio signals to provide a fit quality indicator for a given time period.

[0074] According to one embodiment, the apparatus 100 comprises a processor 111 adapted to execute or control the modelling module 110 and the fit quality assessor 120. It should be appreciated that the processor 111 may be a digital signal processor (DSP).

[0075] Interference Detector

[0076] Now refer to Figure 1BAccording to one embodiment, the signals captured by the internal microphone 106 and the external microphone 104 are received by an interference detector 112. Interference detector 112 uses the highest value of the filter coefficients determined by modeling module 110 as input and provides an activation flag to modeling module 110. If the difference between the highest filter coefficient of the current sample and the highest filter coefficient of the previous sample is below a predetermined threshold, the filter associated with the current sample may be affected by some interference, and the estimated filter for the current sample is considered inaccurate and unsuitable for evaluating the quality of fit. Therefore, in this case, the activation flag is negative, and the modeling module ignores the estimated filter and resets or sets the estimated filter to a previous state. Interference is generally understood as a component of the signal that may cause divergent results from modeling module 110. For example, speech from the user, headset operation, non-sound events generated by the user, or non-stationary transient sounds are generally considered interference. When interfered with, the filter coefficients resulting from coefficient adjustment may not accurately model the worn headset.

[0077] Modeling Module

[0078] like Figure 1C As shown, according to one embodiment, the modeling module 110 includes a filter estimator 114 and a filter coefficient identifier 116. The filter estimator 114 is configured to receive a captured outer ear audio signal and a captured inner ear audio signal to adaptively estimate a filter based on the outer ear audio signal and the inner ear audio signal. According to one embodiment, the filter estimator 114 is configured to iteratively provide an estimate of the outer ear audio signal contribution within the ear canal based on the captured outer ear audio signal and the captured inner ear audio signal. The estimate of the outer ear audio signal contribution within the ear canal is determined by iteratively comparing a preliminary estimate of the outer ear audio signal contribution within the ear canal with the captured inner ear audio signal and modifying the preliminary estimate of the outer ear audio signal contribution based on the comparison. Typically, after several iterations, which may take approximately 2 seconds, the comparison between the iteratively modified estimate of the outer ear audio signal contribution within the ear canal and the captured inner ear audio signal indicates similarity, and the difference between the two signals converges toward zero. As the difference between the two signals converges toward zero, the filter estimator provides an iteratively modified estimate of the outer ear audio signal contribution within the ear canal as an estimated filter. In effect, the filter is estimated by attempting to reduce the error between the captured inner ear audio signal and the estimated outer ear audio signal contribution within the ear canal. The filter coefficient identifier 116 is adapted to identify the coefficients of the estimated filter.

[0079] According to one embodiment, the estimated filter is an adaptive filter, such as a normalized least mean square filter (nLMS). At a sampling rate of 8 kHz, the coefficient set of the nLMS filter includes at least one hundred coefficients, or any suitable number of coefficients to accurately determine the fit quality of the headphone at a given sampling rate. The coefficients are determined in real time, as the outer and inner ear signals are captured, or after a slight delay that is not noticeable to the user.

[0080] According to one embodiment, the adaptive filter is adapted to characterize the fit quality or electroacoustic components of the earphone 102 based on the captured outer ear audio signal and the in-ear audio signal for noise reduction of the outer ear audio signal, for example, when the digital filter is adapted to provide in-ear microphone speech enhancement. In fact, the audio wearable device can use the adaptive filter calculation for speech enhancement and for evaluating the fit quality of the earphone.

[0081] The proposed solution is suitable for providing an assessment of the fit quality of the earphones on a continuous, periodic, or on-demand basis. The digital filter can be configured to estimate the attenuation model of the earphones continuously, periodically, or on-demand while in use. The attenuation model represents the impulse response of the acoustic path of the earphone device, for example when the measured IEM or OEM signal has reached a given energy threshold. The estimation provided by the modeling module 110 is ideally performed when the wearer is not speaking, so as to estimate the acoustic path based on the passive attenuation of the earphones 102.

[0082] Therefore, the proposed method and system are able to seamlessly estimate the headphone fit quality in a noisy environment by quickly and simply determining the filters based on the captured inner and outer ear audio signals.

[0083] Fit Quality Evaluator

[0084] According to one embodiment, Figure 2A As shown, the fit quality evaluator 120 includes a coefficient analyzer 202 and a fit quality determiner 206. The coefficient analyzer 202 is generally adapted to determine to what extent the coefficients of the filter lie within a threshold envelope. If all coefficients are within the threshold envelope, the fit quality determiner 206 determines that the fit quality indicator represents a "good" fit quality. If a few coefficients are outside the threshold envelope, the fit quality determiner 206 determines that the fit quality indicator represents an "uncertain" fit quality. However, if most coefficients are outside the threshold envelope, the fit quality determiner 206 determines that the fit quality indicator represents a "poor" fit quality.

[0085] It will be appreciated that the threshold profile is a predetermined threshold profile based on statistical analysis of previously acquired data.

[0086] According to one embodiment, Figure 3A As shown, coefficient analyzer 202 receives several sets of filter coefficients and is adapted to determine to what extent the filter coefficients are within a threshold envelope using threshold envelope analyzer 208. Coefficient analyzer 202 then performs averaging of the results using averaging module 210. The average of the results is then received by fit quality determiner 206 to determine a fit quality indicator with greater accuracy.

[0087] According to one embodiment, the filter is a FIR filter, such as Figure 2B As shown, the fitting quality evaluator 120 has a frequency response extractor 204 and a fitting quality determiner 206. The frequency response extractor 204 is adapted to calculate or extract a frequency response over a predetermined frequency band range or over a predetermined discrete frequency band (e.g., between 150 Hz and 350 Hz) by calculating the FFT of the impulse response based on the coefficients of the FIR filter. The fitting quality determiner 206 determines a fitting quality indicator based on the average value of the extracted frequency response. For example, Figure 3C As shown, if the average value of the extracted frequency responses is below a good fit upper threshold, the fit quality determiner 206 determines the fit quality as indicating a "good" fit quality. If the average value of the extracted frequency responses is above a poor fit lower threshold, the fit quality determiner 206 determines the fit quality as indicating a "poor" fit quality. Additionally, if the average value of the extracted frequency responses is between a poor fit lower threshold and a good fit upper threshold, the fit quality determiner 206 determines the fit quality indicator as indicating an indeterminate fit quality.

[0088] According to one embodiment, Figure 3B As shown, the response extractor 204 receives several sets of filter coefficients and is adapted to determine, using a response calculator 212, to what extent the calculation results for the frequencies associated with each set of coefficients are within an acceptable range. The response extractor 204 then performs averaging of the calculation results using an averaging module 214. The average of the calculation results is then received by the fit quality determiner 206 for precisely determining a fit quality indicator with greater accuracy.

[0089] According to one embodiment, Figure 2C As shown, the fit quality evaluator 120 includes a coefficient analyzer 202, a response extractor 204, and a fit quality determiner 206. The fit quality determiner 206 is adapted to determine a fit quality indicator based on how well the coefficients of the filter are within a threshold envelope and based on responses calculated at different predetermined frequencies associated with the filter.

[0090] It should be appreciated that the fit quality indicator determined by fit quality determiner 206 can be presented in various forms and levels of precision. For example, fit quality determiner 206 can present the fit quality indicator based on a percentage value, a numeric value, a binary value, or any other type of value based on any number of appropriate levels.

[0091] It should also be appreciated that once the fit quality indicator 152 is determined, the communication module 154 may send status information corresponding to the fit quality indicator to the wearer or a monitoring device or system, such as Figure 3D shown.

[0092] According to another aspect, a method 400 for evaluating a quality of fit is provided. The method 400 includes receiving an inner ear sound signal at 402 and receiving an outer ear sound signal at 404. The method also includes determining a filter at 406 based on the inner ear sound signal and the outer ear sound signal at 404. The coefficients of the filter are then identified at 408 and the quality of fit is determined at 410 based on the identified coefficients.

[0093] according to Figure 4B In another embodiment shown, the method for evaluating the quality of fit at 400 further includes verifying the filter accuracy based on the identified coefficients at 409. According to one embodiment, if the difference between the highest coefficients of two consecutive samples exceeds a predetermined threshold, the filter is determined to be inaccurate, for example due to the presence of speech.

[0094] It should be appreciated that this can be achieved in various ways. Figure 4A and 4B The method 400 for evaluating the quality of a fit is shown. For example, the coefficients (e.g., Figure 4C ) and / or extracting the frequency response at 414 (as shown Figure 4D and 4E ) to perform determining the quality of fit at 410 so as to determine the quality of fit at 416. When both the analysis coefficients are applied at 412 and the frequency response is extracted at 414, the quality of fit can be determined at 416 with greater accuracy than when only one of the analysis at 412 or the extraction at 414 is applied.

[0095] It should also be recognized that Figure 4F As shown, once the fit quality indicator is determined at 416 , the fit quality indicator may be communicated to the wearer, to a monitoring device, or to a system at 452 .

[0096] Figure 5AAn example implementation of performing a fit quality assessment 400 by analyzing coefficients 412 according to one embodiment is shown in FIG. Based on the presence of the identified filter coefficients within one or more predetermined envelopes, a fit quality indicator is determined. In some embodiments, the method may further include averaging the filter coefficients 1214. Averaging step 1214 generally improves the reliability of the calculation, but is not required.

[0097] exist Figure 5B An example implementation of performing fit quality assessment 400 by extracting responses 414 according to one embodiment is shown in FIG. Extracting responses 414 typically requires more computation and is less efficient. However, extracting responses 414 allows different types of interference to be identified with greater accuracy.

[0098] Figure 5A A method 400 for assessing quality of fit by analyzing coefficients 412 is shown according to one embodiment. Method 1210 includes determining FIR filter coefficients 1213 based on signals captured from OEM 104 and IEM 106. Method 400 may include waiting for a predetermined duration 1211. This delay may ensure that a previous value fit verification test is completed or may be triggered by a user. Method 400 also includes initializing various counters and / or variables 1212, such as, but not limited to, a counter for calculated good fits, a number of processed fit tests, and / or filter coefficient values.

[0099] In one embodiment, the method 400 further includes performing filter adaptation using the adaptive filter 110 (nLMS) for a predetermined duration 1213 .

[0100] like Figure 5A The illustrated fit assertion method 400 also includes asserting a fit using a coefficient envelope 412. The method 400 includes testing 1214 whether the coefficients of the adaptive filter 110 are within an envelope of values associated with an acceptable or good fit for the headphone 102. Figure 5B The maximum and minimum thresholds for each coefficient value of the filter are shown in .

[0101] One method for verifying whether a good fit is provided across multiple filters or samples is to count the number of good-fit filters and determine whether that number is acceptable. If the identified filter coefficient value is within a predetermined envelope, the counter is incremented as another good-fit filter 1216. If there are more filters to be analyzed, steps (1212 to 1217) are repeated for the filter coefficient values of the next sample. When the predetermined number of filters to be analyzed is reached 1218, the number of good-fit filters is compared to an upper limit of poor fit 1219 or to a lower limit of good fit 1221. If the number of good-fit filters is below the upper limit of poor fit, a "poor fit" is determined 1220. If the number of good-fit filters is above the lower limit of good fit, a "good fit" is determined 1223. However, if the number of good-fit filters is between the upper limit of poor fit and the lower limit of good fit, an "uncertain fit" is determined 1222.

[0102] It should be appreciated that the number of analysis filters 1218 may be any predetermined number of filters, and may be a plurality of filters, such as ten filters, or may be just one filter.

[0103] Reference Figure 5B In another embodiment, method 1230 uses response extraction 414 to calculate the frequency response at different predetermined frequencies. In some embodiments, the method may also include averaging the filter coefficients 1234. The averaging stage 1248 generally improves the reliability of the calculations, but is not required. Method 414 generally requires more calculations or more processing power than filter coefficient method 412. However, response extraction method 414 may be more sensitive to different types of interference. One advantage of this method 414 is that it provides an estimator of the quality of fit (a span of values) as opposed to another method 412 that only provides a state or states as output.

[0104] For example, according to one embodiment Figure 5B As further shown in FIG. 1 , the fit assertor module 120 is adapted to wait for a predetermined duration 1231. This delay can ensure that a previous value fit verification test is completed or triggered by a user. The fit assertor module 120 is further adapted to initialize various counters and / or variables 1232, such as, but not limited to, frequency response averages and / or filter coefficient values.

[0105] According to one embodiment, the fit assertor module 120 performs adaptation of the filter 110 (nLMS) for a predetermined duration 1233 in order to estimate the filter.

[0106] Once the filter is estimated, the fit assertor module 120 is adapted to calculate the response at different predetermined frequencies 414. The method 414 includes extracting 1234 the frequency response of a set of predetermined frequency bands, for example between 150 and 350 Hz. This extraction can be performed by Figure 2B and 2C The frequency response extractor module 204 performs the response extraction 1234. The response extraction 1234 generates the adaptive coefficients by computing the fast Fourier transform (FFT) of the impulse response.

[0107] Method 414 also includes calculating an average of the frequency band responses (band average) for each response 1235. Optionally, method 414 may also determine response consistency based on the received frequency band responses (coherence curve) 1235 to detect interference. In some embodiments, method 414 may further verify whether the calculated coherence curve is high and / or exceeds a threshold curve 1236 for all responses. If verification 1236 is negative, the response averages and filter coefficients are reset 1232, another filter is estimated 1233, and the frequency response is extracted to generate filter coefficients 1234. The frequency band response averages are then calculated again and response coherence is determined 1235. If verification 1236 is positive, method 414 verifies whether adaptive filter interference or an inappropriate audio environment is detected during adaptation 1237. If verification 1237 is positive, the previous steps 1232 through 1235 (and optionally 1236) are repeated. If the verification 1237 is negative, the method 414 inserts and / or adds the band average (“BandAverage”) to the response average (ResponseAverage) 1238 .

[0108] According to one embodiment, when a predetermined number of iterations is reached, or when the response average encompasses a predetermined number of iterations 1239 (“Y” iterations), the response average may be used to assess the fit quality of the earphone 102 .

[0109] According to one embodiment, method 414 verifies at 1240 whether the response average is above a predetermined value that is considered the lowest value for a poor-fit configuration (a "bad fit floor"). If the response average is above the predetermined value, the fit is deemed poor or unacceptable 1241. Method 414 also verifies whether the response average is below a predetermined value that is considered the highest value for a good-fit configuration 1244 (a "good fit ceiling"). If the response average is below the predetermined value, the fit quality is deemed good or acceptable 1244. However, if the response average is between the "bad fit floor" and the "good fit ceiling," the fit quality of earphone 102 cannot be assessed, and method 414 is deemed indeterminate 1240.

[0110] Return Reference Figure 5C According to another embodiment, there is a method 1250 that executes the coefficient analysis method 412 and the response extraction method 414. According to one embodiment, the coefficient analysis method 412 and the response extraction method 414 are executed in parallel to provide a real-time assertion of the fit of the earphone 102. The method 1250 provides an assessment of the quality of fit of the earphone 102 with greater reliability or accuracy than the response extraction method 414 or the coefficient analysis method 412 executed separately. The fit is considered good or acceptable only when both methods 412 and 414 return output values indicating a good or acceptable fit. The third method 1250 outputs a bad or unacceptable fit status ("BadFit") only when both methods (412 and 414) return a bad or unacceptable fit status. In all other cases, the third method 1250 returns an indeterminate status or output.

[0111] Figure 4A and 4B The proposed method 400 can be provided by a fit assessment system for headphones having an external microphone for capturing outer ear audio signals outside the ear canal and an internal microphone for capturing inner ear audio signals inside the ear canal. The fit assessment system generally includes a first receiver 104 adapted to receive the captured outer ear audio signals and a second receiver 106 adapted to receive the captured inner ear audio signals. The system also includes a modeling module 110 adapted to be connected to the first receiver 104 and the second receiver 106 and to estimate a filter based on the captured outer ear audio signals and the captured inner ear audio signals, the filter representing the attenuation provided by the headphone 100 when used in a noisy environment. The system also includes a coefficient identifier adapted to identify a set of filter coefficients based on the estimated filters; and a fit quality assessor adapted to analyze the set of filter coefficients and determine at least one fit quality metric based on the analysis. The system includes a fit quality communication module adapted to transmit status information representing the fit quality metric to the wearer or a monitoring system.

[0112] Fit quality in quiet environments

[0113] According to another aspect, an audio wearable device and a method for determining the seal quality of an earphone of the device when in a silent or quiet environment are provided. The apparatus and method of the present invention allow for real-time assessment of the seal quality of an earphone for adequate hearing protection or communication, or for improving the signal-to-noise ratio of distortion product otoacoustic emissions (DPOAE) measurements.

[0114] According to one embodiment, the apparatus and method allow for determining earphone seal quality while simultaneously calibrating a stimulus based on otoacoustic emission tones in order to perform otoacoustic measurements. Indeed, determining proper seal quality before or during otoacoustic measurements can be beneficial, as otoacoustic measurements must be performed with earphones that provide a proper seal in order to obtain accurate measurements. However, it should be appreciated that the seal quality assessment methods and apparatus described herein can also be simply implemented to assess the seal quality of earphones in a quiet environment.

[0115] exist Figure 6A FIGURE 6 illustrates an audio wearable device 600 according to one embodiment, comprising an earphone 602, such as, but not limited to, an earbud, an in-the-ear device, or any other type of device for preventing sound or noise from entering the ear canal 12. The earphone 602 typically includes two internal speakers (SPK) (604a and 604b) positioned to transmit two pure tone frequencies, or stimuli, at known frequencies into the ear canal. One of the speakers 604a is connected to a sound source 610 adapted to produce at least one of the two pure tone frequencies. When otoacoustic emission measurements are also being performed, the other speaker 604b can be connected (not shown) to the sound source 610 and receive the other of the two pure tone frequencies. The earphone 602 also includes an internal microphone (IEM) 606, positioned to capture acoustic signals generated in the ear canal in response to the stimuli (i.e., otoacoustic emission tones). The device 600 also includes a processor 608, such as a digital filter, adapted to receive and process measurements of the acoustic signals received by the IEM. The processor 608 is configured to compare the stimuli with the received signals and estimate a transfer function representative of the seal quality. It will be appreciated that the transfer function also represents the resonance amplitudes and anti-resonance amplitudes specific to the shape and volume of the ear canal (ie the acoustics of the ear canal) and the sealing quality of the earphone and earphone acoustics at a given frequency.

[0116] It will be appreciated that, upon stimulation, the acoustic signal generated within the ear canal comprises the stimulation and reflected acoustic signals from within the ear canal, such as from the eardrum 14. The characteristics of the reflected acoustic signals depend on the shape and volume of the ear canal, the earphone acoustics, and the quality of the earphone seal.

[0117] It should also be appreciated that the received in-ear sound signal may be a signal having, for example, a resonance or anti-resonance resulting from a combination of the stimulus emitted at a given frequency and the reflected signal. The received in-ear sound signal may also be a signal that follows a Helmholtz resonator model, indicating an inadequate seal of the earplug. It will be appreciated that in the presence of a good seal, the Helmholtz resonator effect will not be present in the received in-ear sound signal.

[0118] It should also be appreciated that, depending on the otoacoustic measurement method, the two internal speakers (604a and 604b) may be replaced by a single speaker. Furthermore, to assess the quality of fit in a quiet environment only, a single speaker 604a connected to a sound source 610 will be sufficient.

[0119] In one embodiment, to perform distortion producing otoacoustic emissions (DPOAE) measurements, the stimulus includes at least frequencies in the range of 600 Hz to 7000 Hz. Note that DPOAE is the "response when the cochlea is stimulated simultaneously by two pure tone frequencies," so each of the two speakers (604a and 604b) produces one of the two pure tone frequencies simultaneously. For example, the stimulus can be white noise or a linear frequency chirp, i.e., a sinusoidal sweep signal, whose frequency is in the range between 600 Hz and 7000 Hz. The white noise or linear frequency chirp can have a duration of approximately 10 seconds or any other duration sufficient to allow the processor to determine the transfer function. Note that the processor determines the transfer function by comparing the stimulus with the received signal in order to converge to a minimum or acceptable error. It should be appreciated that the stimulus can be any other type of signal besides white noise or linear frequency chirp, as long as the stimulus provides enough discrete frequencies within the required frequency range.

[0120] According to one embodiment, the IEM is associated with a conditioning circuit. The associated conditioning circuit has a high sensitivity and is suitable for detecting sound pressure levels as low as -20 dB (SPL). Therefore, stimuli such as white noise or linear frequency modulation pulses can be generated at very low sound levels, such as at about 0 dB (SPL), and the IEM is still able to detect the reflected sound wave signal generated in the ear canal. In this case, the stimulus is inaudible to the user and has a negligible effect on the user's cumulative noise dose. Therefore, the present solution is suitable for continuously evaluating the sealing quality of the earphones when the earphones are worn in a quiet environment, for example when performing audiometric measurements, or before entering a noisy environment when the earphones are used as HPD (hearing protection device).

[0121] According to one embodiment, the processor 608 is adapted to establish a set of signal amplitudes for various frequencies, respectively, depending on the transfer function. For example, in order to calibrate a stimulus for a distortion product otoacoustic emission (DPOAE) measurement, the processor is adapted to establish signal amplitudes associated with frequencies having a range between 600 Hz and 10,000 Hz. The processor is also adapted to establish signal amplitudes associated with lower frequencies, for example in a range between 100 Hz and 600 Hz, for evaluating the seal quality. According to one embodiment, in order to evaluate the seal quality, it is only necessary to establish a signal amplitude for a single frequency, for example 150 Hz or any other predetermined single frequency or combination of frequencies that is known to clearly characterize a leak. For example, if Figure 8As shown in the graph, it can be noted that at 150 Hz, the signal amplitude varies depending on the "no leak" or leak size radius ranging from r1 to r3. Therefore, the signal amplitude at 150 Hz clearly indicates a leak. The processor is further adapted to determine a seal quality indicator based on the established signal amplitude.

[0122] It will be appreciated that the established set of signal amplitudes represents a set of gain correction values to be applied to the otoacoustic emission stimulation at various frequencies, respectively.

[0123] According to one embodiment, the processor provides a seal quality indicator based on the transfer function. The seal quality indicator can be a PAR (Personal Attenuation Rating) indicator, a leak size indicator, a leak length indicator, a leak volume indicator, a fit quality indicator or any other type of seal quality indicator.

[0124] It should be understood that the device 600 does not require an external sound source. When performed in a noiseless environment and without the user making any sound, a better seal quality assessment can be provided. In a quiet environment, a stimulus is delivered for a few seconds, and the earphone seal quality is determined based on the determined transfer function.

[0125] Figure 6B 6 shows various seal quality assessment components of an audio wearable device 600 according to one embodiment. The device 600 includes a modeling module 612 adapted to determine a transfer function based on the stimulus generated by the sound source 610 and the signal received by the inner ear microphone 606. The device 600 also includes a seal quality assessor 614, which is generally adapted to determine a seal quality indicator based on the transfer function. Figure 6C As shown, the seal quality evaluator 614 includes a signal amplitude identifier 616 adapted to identify the signal amplitude at a predetermined seal evaluation frequency. The predetermined seal evaluation frequency is at least one frequency at which the signal amplitude of the known transfer function differs depending on the seal quality. For example, Figure 8 As shown, it has been determined that at 150 Hz, the seal quality, such as the leakage size radius of the earphone, can be identified based on the signal amplitude. The seal quality determiner 618 then determines the seal quality based on analysis, calculation, or based on a lookup table (e.g. Figure 6D In the latter case, the seal quality determiner 618 is adapted to compare the identified signal amplitude with the reference signal amplitudes of the lookup table 622. The reference signal amplitude is first measured and stored in the lookup table 622 along with the associated seal quality indicator. The seal quality determiner 620 is adapted to determine the seal quality indicator corresponding to the identified signal amplitude and the seal evaluation frequency.

[0126] It should be appreciated that the signal amplitude identifier 616 can identify multiple signal amplitudes of the transfer function, each signal amplitude corresponding to a different seal evaluation frequency of the predetermined set of seal evaluation frequencies. The seal quality determiner 618 can then analyze the multiple signal amplitudes and select only one corresponding to the most accurate seal quality indicator. The seal quality determiner 618 can also analyze the multiple signal amplitudes, select a corresponding multiple seal quality indicators, and provide an average of the corresponding seal quality indicators to determine a seal quality indicator with greater accuracy.

[0127] It should also be appreciated that once the fit quality indicator is determined at 652, the communication module 654 can send status information corresponding to the fit quality indicator to the wearer, the speaker (604a or 604b), or the monitoring system, such as Figure 6E shown.

[0128] Device using adaptive filter

[0129] According to one embodiment of the device 600, the processor 608 may be adapted to execute instructions defined in the modeling module 612, such as Figure 6A As shown. In such an embodiment, the modeling module 612 is an adaptive filter. The filter module 612 is adapted to receive a stimulus signal from the sound source 610, referred to herein as a reference x(n) signal input, and a captured signal from the IEM 606, referred to herein as a desired d(n) signal input. It should be understood that the sound source 610 can be connected to two speakers 604a and 604b and can simultaneously generate two pure tone frequencies suitable for generating DPOAE measurements (e.g., one pure tone frequency for each channel or speaker). The filter module 612 uses the above-mentioned desired d(n) and reference x(n) signal inputs to identify the transfer function between the electrical signal of the speakers (604a and 604b) and the signal captured by the IEM 606. The stimulus signal generated by the sound source 610 can be composed of a low-amplitude linear frequency chirp or a broadband noise signal. In other embodiments, the linear frequency chirp can be reversed (from high to low frequency) to improve low-frequency estimation.

[0130] like Figure 6A As further shown, the stimulation signals from the speakers (604a and 604b) are used as reference x(n) signals for the filter module 612, and the signal captured by the IEM 606 is used as the desired d(n) signal. According to one embodiment, the coefficients of the filter module 612 converge to a transfer function of the response of the speakers (604a and 604b) combined with the response of the ear canal 12 and the IEM 606, which is based on the following equations (1) to (4):

[0131] (1)

[0132] (2)e(n)=d(n)-y(n)

[0133] (3)

[0134] (4)

[0135] The average value of the transfer function is often referred to as the estimated transfer function H(z). In this case, the adaptive filter 612 is a normalized least mean square (NLMS) adaptive filter, and the magnitude response M(z) of the estimated sealing transfer function H(z) is calculated from the NLMS coefficients using equation (4), where z=e jω ,ω=2πf, is the NLMS coefficient and N is the number of coefficients used for the NLMS adaptive filter.The amplitude M can also be estimated at discrete frequencies f, such as but not limited to f = 150 Hz.

[0136] The amplitude M is typically used to assess the fit or seal quality of the earphone 602, but can also be used to calibrate the DPOAE stimulus signals f = f1 and f = f2. In an embodiment using two speakers (604a and 604b), when f = f2, the sound source 610 signal is transmitted to the second speaker (604a and 604b). The calibration of the stimulus signal consists in adjusting the gain of the discrete main tone based on the difference between the amplitude at, for example, 0 dB at 1000 Hz and at the discrete frequencies f1 and / or f2.

[0137] Methods for evaluating seal quality

[0138] Figure 7A , a method 700 for evaluating the seal quality of an earphone 602 according to one embodiment is shown. Method 700 generally includes generating a stimulus signal in the ear canal at step 702 and capturing a reflected signal generated in the ear canal based on the stimulus signal at step 704. The method also includes estimating a transfer function based on the generated stimulus signal and the captured signal at step 706. Seal quality is then determined based on the transfer function at step 708.

[0139] It should be appreciated that the reflection signal generated in the ear canal includes the reflected sound signal from the ear canal according to the stimulus and the emitted stimulus signal. The characteristics of the reflection signal depend on the shape and volume of the ear canal, the acoustics of the earphone and the sealing quality of the earphone. In addition, the reflection signal generated in the ear canal can be a signal having, for example, a resonance or anti-resonance, which is generated at a given frequency by the combination of the generated stimulus and the reflection signal. The reflection signal can also be a signal that follows a Helmholtz resonator model, which indicates an improper seal of the earphone. Note that in the case of good sealing quality, there will be no Helmholtz resonator effect in the reflection signal.

[0140] Figure 7B A method of estimating a transfer function 706 according to one embodiment is shown in . The method 706 includes comparing the stimulus signal with the reflected signal at step 710 and then estimating a transfer function that allows the comparison to converge to an acceptable error at step 712 .

[0141] Figure 7C A method 708 for determining a seal quality indicator according to one embodiment is shown. The method 708 includes establishing a signal amplitude associated with a predetermined seal evaluation frequency based on the estimated transfer function at step 720. Then, at step 724, a seal quality indicator is determined based on the established signal amplitude.

[0142] Figure 7D A method 730 for performing otoacoustic emission measurements is shown. Method 730 includes step 700 of evaluating the seal quality of the earphone. If the seal quality is good, method 730 further includes step 732 of establishing a set of signal amplitudes associated with the DPOAE stimulation frequency based on the estimated transfer function. Then, step 734 of evaluating a gain correction value based on the established set of signal amplitudes is performed, and step 736 of applying the established gain correction value at the otoacoustic emission stimulation frequency is performed, so that step 738 of providing an otoacoustic measurement is performed.

[0143] It should be recognized that Figure 7E As shown, once the seal quality indicator is determined at step 708 , the seal quality indicator may be communicated to the wearer, a monitoring device, or a system at step 752 .

[0144] Partial results

[0145] Now refer to Figure 8 , according to one embodiment, a graph 800 is presented that presents a comparison of different responses of standardized microspeakers (604a and 604b) in a leaking earplug and a non-leaking earplug located in the ear canal 12. The different results of graph 800 correspond to an earphone with no leakage and an earphone with a leakage radius size ranging from r1 to r3. Figure 8 As shown, for headphones with leakage, a decrease in amplitude at lower frequencies is observed. As shown in graph 800, the extent of leakage can be estimated by measuring the amplitude at 150 Hz. At 150 Hz, the measured amplitude of the response varies with greater differences depending on the size of the leakage radius.

[0146] Now refer to Figure 9 , according to one embodiment, presents a graph 900 of the magnitude response calculated from the coefficients of an adaptive filter. In this case, the response is normalized to 0 dB. As shown in graph 900, the magnitude of the response is similar to other estimation methods, especially for lower frequencies.

[0147] Now refer to Figure 10 , according to one embodiment, a graph 1000 is presented of various passive attenuation levels provided by custom-fit headphones worn by five different users and measured at different times of the day on different days. The lower graph (solid line) 1002 refers to a good seal based on criteria in the 250 Hz octave band, while the upper graph (dashed line) 1004 refers to a poor seal based on the same criteria.

[0148] Now refer to Figure 11 , according to one embodiment, a graph 1100 is presented showing a linear regression of passive attenuation (dB) as a function of seal rating (dB). The linear regression uses the seal rating at 150 Hz on the x-axis and the passive attenuation of the earphone calculated from the difference in the automatic spectrum between the OEM and IEM at 500 Hz. 2 is the coefficient of determination on the y-axis. It will be appreciated that passive attenuation can be estimated over a frequency range from 125 Hz to 16,000 Hz.

[0149] Now refer to Figure 12 , according to one embodiment, graph 1200 shows a linear regression of personal attenuation rating (dB) at 500 Hz as a function of seal rating (dB) in one embodiment. The multiple linear regressions show the passive attenuation of the earphones, calculated by the difference in the auto spectrum between the OEM and IEM at 500 Hz on the x-axis and the personal attenuation rating (PAR) on the y-axis. 2 is the coefficient of determination on the y-axis. It will be appreciated that the passive attenuation may have an octave band on the x-axis from 125 Hz to 8000 Hz.

[0150] Now refer to Figure 13 , according to one embodiment, a graph 1300 is presented which presents a linear regression of the above seal evaluation at 150 Hz on the x-axis and the personal attenuation rating (PAR) on the y-axis, R 2 is the coefficient of determination.

[0151] It will be appreciated that the seal quality indicator may be a PAR (Personal Attenuation Rating) indicator, a leak size indicator, a fit quality indicator, or any other type of seal quality indicator.

[0152] Sealing test in quiet or noisy environment

[0153] according to Figure 14In one embodiment shown, there is an apparatus 1400 for evaluating the quality of a seal in a silent environment or in a noisy environment. The device 1400 includes an earphone 1402 having at least one speaker 1404 connected to a sound source 1410, the sound source 1410 being adapted to provide a pure tone signal at a predetermined seal evaluation frequency. The earphone 1402 also includes an inner ear microphone 1406 adapted to capture internal audio signals from the ear canal 12 and an outer ear microphone 1408 adapted to capture external audio signals from external sound sources (e.g., noise from the environment). The device 1400 also includes a noise detector 1416 adapted to receive the external audio signal and determine whether the device 1400 is being worn in a noisy environment or in a quiet or silent environment. When in a noisy environment, the first adaptive filter 1412 is activated and, based on Figure 4A and 4B When in a quiet or silent environment, the second adaptive filter 1412 is activated and the second adaptive filter 1412 is activated according to the method 400. Figure 7A The method 700 determines a seal evaluation indicator.

[0154] It should also be appreciated that the estimated transfer function can be compared with another transfer function determined according to another seal quality assessment method to more accurately assess the seal quality. Figure 4A and 4B The estimated transfer function can be compared with another transfer function determined by the fitting quality assessment method 400 shown, and the sealing quality can be assessed with higher reliability. In addition, the estimated transfer function can be compared with the transfer function generated in a noisy environment, such as Figure 14 shown.

[0155] Seal quality assessment system

[0156] According to one embodiment, the proposed method 700 can be provided by a seal quality assessment system for headphones having a speaker for emitting sound into the ear canal and an internal microphone for capturing inner ear audio signals within the ear canal. The seal quality assessment system includes a sound source generator adapted to generate a sound stimulus at a predetermined seal assessment frequency and a receiver adapted to receive the inner ear audio signal of the sound stimulus captured by the internal microphone. The system also includes a modeling module adapted to estimate the transfer function of the headphones when used in a quiet environment based on a comparison of the sound stimulus and the received inner ear audio signal. The system also includes a signal amplitude identifier adapted to establish the signal amplitude of the transfer function at the predetermined seal assessment frequency and a seal quality evaluator adapted to determine at least one seal quality indicator based on the signal amplitude. The system includes a seal quality communication module adapted to transmit status information representing the seal quality indicator to a wearer or a monitoring system. Once the fit quality indicator is determined, the communication module can transmit status information corresponding to the fit quality indicator to the wearer or the monitoring system.

[0157] Embodiments of the present systems, devices, and methods generally require reduced or low computation time. Limited computation time is typically achieved by using computational methods other than Fast Fourier Transform (FFT) computations. The proposed solution utilizes a processor configured to provide adaptive filtering to efficiently identify transfer functions or filter coefficients at low computational cost.

[0158] The proposed solution allows for providing an assessment of the seal quality of earphones. The solution can be used for any type of audio wearable device that includes a desired audio sensor, such as in-ear / on-ear or external-ear wearable devices. In some embodiments, the audio sensor can be a microphone located outside the device, below the device, or a speaker typically located below the device.

[0159] Thus, the proposed method 700 is able to provide a continuous, periodic, or on-demand estimate of the fit of the headphones, while being simply calculated in real time or with a slight imperceptible delay within the standalone in-ear audio wearable device 600 in a quiet environment.

[0160] Although exemplary and presently preferred embodiments of the invention have been described in detail above, it should be understood that the concepts of the invention may be otherwise variously embodied and used, and that the appended claims are intended to be interpreted to include such variations beyond the scope of the prior art.

Claims

1. An audio wearable device having an earphone operable to prevent ambient sound from entering an ear canal of a user, the earphone comprising a sound emitting device positioned toward the ear canal and a sound capturing device within the ear canal, the audio wearable device comprising: a sound source generator adapted to generate sound stimulation at a predetermined seal assessment frequency; a sound source transmitter adapted to transmit sound stimuli to the sound emitting device and the modeling module; the modeling module being configured to estimate a transfer function of the earphone when used in a quiet environment based on a comparison of the sound stimulus and an inner ear audio signal of the sound stimulus captured by a sound capture device; a signal amplitude identifier configured to establish a signal amplitude of the transfer function at a predetermined seal evaluation frequency; and A seal quality evaluator is adapted to determine at least one seal quality indicator based on the established signal amplitude. 2 . The audio wearable device of claim 1 , wherein the seal quality evaluator is further configured to determine the at least one seal quality indicator based on a dataset of previously measured seal quality indicators. 3 . The audio wearable device of claim 1 , wherein the sound source generator is configured to generate sound stimulation at a plurality of predetermined seal assessment frequencies.

4. The audio wearable device of claim 3 , wherein the signal amplitude identifier is further configured to establish a plurality of signal amplitudes based on the transfer function and the plurality of predetermined seal evaluation frequencies, and the seal quality evaluator is adapted to determine at least one seal quality indicator based on the plurality of signal amplitudes. 5 . The audio wearable device according to claim 1 , wherein the sound source generator is further adapted to generate a plurality of sound stimuli at a plurality of predetermined otoacoustic emission measurement calibration frequencies. 6 . The audio wearable device of claim 5 , wherein the predetermined seal assessment frequency is one of the plurality of otoacoustic emission measurement calibration frequencies.

7. The audio wearable device of claim 6, wherein the plurality of sound stimuli comprises two pure tone frequencies.

8. A seal quality assessment system for an earphone, the earphone being configured to prevent ambient noise from entering an ear canal of a wearer and having a sound emitting device for emitting sound into the ear canal and a sound capturing device within the ear canal, the seal quality assessment system comprising: a sound source generator configured to generate sound stimulation at a predetermined seal assessment frequency; a sound source transmitter configured to transmit the sound stimulus to the sound emitting device; and a modeling module adapted to receive an inner ear audio signal of the sound stimulus captured by the sound capturing device; The modeling module is further configured to estimate a transfer function of the earphone when used in a quiet environment based on a comparison of the sound stimulus and the received inner ear audio signal; a signal amplitude identifier adapted to establish the signal amplitude of said transfer function at a predetermined close evaluation frequency; and A seal quality evaluator is adapted to determine at least one seal quality indicator based on the signal amplitude.

9. The seal quality assessment system according to claim 8, wherein the seal quality assessor is adapted to determine the at least one seal quality indicator based on a data set of previously measured seal quality indicators.

10. The seal quality assessment system of claim 8, wherein the sound source generator is adapted to generate sound stimuli at a plurality of predetermined seal assessment frequencies.

11. The seal quality assessment system of claim 10, wherein the signal amplitude identifier is adapted to establish a plurality of signal amplitudes based on the transfer function and the plurality of predetermined seal assessment frequencies, and the seal quality assessor is adapted to determine at least one seal quality indicator based on the plurality of signal amplitudes.

12. The seal quality assessment system according to any one of claims 8 to 11, wherein the sound source generator is further adapted to generate a plurality of sound stimuli at a predetermined plurality of otoacoustic emission measurement calibration frequencies.

13. The seal quality assessment system of claim 12, wherein the predetermined seal assessment frequency is one of the plurality of otoacoustic emission measurement calibration frequencies.

14. The seal quality assessment system of claim 12, wherein the plurality of sound stimuli comprises two pure tone frequencies.

15. The seal quality assessment system of claim 8, further comprising a seal quality communication module adapted to transmit status information representative of the at least one seal quality indicator.

16. The seal quality assessment system of claim 15, wherein the status information is sent to the sound emitting device or to a monitoring system.

17. The seal quality assessment system of claim 8, wherein the at least one seal quality indicator is a leak indicator selected from the group consisting of leak radius size, leak length, and leak volume.

18. A method of evaluating the sealing quality of an earphone according to any one of claims 1 to 7, wherein the earphone is configured to prevent ambient noise from entering an ear canal of a wearer, the method comprising: generating a sound stimulus at a predetermined seal assessment frequency; emits sound stimuli into the ear canal; Capture inner ear audio signals in the ear canal; comparing the generated sound stimulus with the captured inner ear audio signal; estimating a transfer function based on a comparison of the generated sound stimulus and the captured inner ear audio signal; identifying a signal amplitude of the transfer function at the predetermined seal evaluation frequency; and At least one seal quality indicator is determined based on the signal amplitude. 19 . The method of claim 18 , wherein determining at least one seal quality indicator further comprises determining the at least one seal quality indicator based on a dataset of previously measured seal quality indicators.

20. The method of claim 18, wherein generating the sound stimulus further comprises generating the sound stimulus at a plurality of predetermined seal assessment frequencies.

21. The method of claim 20, wherein identifying the signal amplitude of the transfer function further comprises identifying a plurality of signal amplitudes based on the transfer function and the plurality of predetermined seal evaluation frequencies, and determining at least one seal quality indicator further comprises determining at least one seal quality indicator based on the plurality of signal amplitudes.

22. The method of any one of claims 18 to 21, wherein generating sound stimuli further comprises generating a plurality of sound stimuli at a predetermined plurality of otoacoustic emission measurement calibration frequencies.

23. The method of claim 22, wherein the predetermined seal assessment frequency is one of the plurality of otoacoustic emission measurement calibration frequencies.

24. The method of claim 22, wherein the plurality of sound stimuli comprises two pure tone frequencies.

25. The method of claim 18, further comprising transmitting status information representative of the at least one seal quality indicator.

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