Patent Publication Number: US-2022240033-A1

Title: Hearing Evaluation Systems and Methods Implementing a Spectro-Temporally Modulated Audio Signal

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 17/161,500, filed Jan. 28, 2021, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND INFORMATION 
     Hearing devices (e.g., hearing aids) are used to improve the hearing capability and/or communication capability of users of the hearing devices. Such hearing devices are configured to process a received input sound signal (e.g., ambient sound) and provide the processed input sound signal to the user (e.g., by way of a receiver (e.g., a speaker) placed in the user&#39;s ear canal or at any other suitable location). 
     When a hearing device is initially provided to a user, and during follow-up tests and checkups thereafter, it is usually necessary to “fit” the hearing device to the user. Fitting of a hearing device to a user is typically performed by an audiologist or the like who presents various stimuli having different loudness levels to the user. The audiologist relies on subjective feedback from the user as to how such stimuli are perceived. The subjective feedback may then be used to generate a hearing profile (e.g., an audiogram) that indicates individual hearing thresholds and loudness comfort levels of the user. Adjustments may be made based on the hearing profile to specifically tailor parameters (e.g., prescriptive gain) of the hearing device to the user. 
     Although a user&#39;s hearing thresholds indicated in a hearing profile are useful in tailoring parameters of a hearing device to the user, end-user feedback and studies have shown that benefits gained from a hearing device fitted with regard to such hearing thresholds may vary greatly. This may be true even within groups of users with almost identical hearing profiles. Accordingly, when it comes to fitting parameters of a hearing device to a user, a typical hearing profile fails to provide sufficient information on individual hearing loss and/or residual hearing of the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate various embodiments and are a part of the specification. The illustrated embodiments are merely examples and do not limit the scope of the disclosure. Throughout the drawings, identical or similar reference numbers designate identical or similar elements. 
         FIG. 1  illustrates an exemplary hearing evaluation system according to principles described herein. 
         FIG. 2  illustrates an exemplary implementation of the hearing evaluation system of claim  1  according to principles described herein. 
         FIGS. 3 and 4  illustrate exemplary graphical depictions of spectro-temporally modulated audio signals according to principles described herein. 
         FIG. 5  illustrates an exemplary flowchart showing operations that may be performed by the hearing evaluation system of  FIG. 1  according to principles described herein. 
         FIG. 6  illustrates an exemplary augmented individual hearing profile that includes modulation detection thresholds that may be determined according to principles described herein. 
         FIG. 7  illustrates an exemplary hearing device fitting workflow depicting exemplary hearing device fitting operations that may be performed according to principles described herein. 
         FIG. 8  illustrates an exemplary method implementing a spectro-temporally modulated audio signal according to principles described herein. 
         FIG. 9  illustrates an exemplary computing device according to principles described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Hearing evaluation systems and methods implementing a spectro-temporally modulated audio signal are described herein. As will be described in more detail below, an exemplary system comprises a memory storing instructions and a processor communicatively coupled to the memory. The processor may be configured to execute the instructions to present a spectro-temporally modulated audio signal to a user (e.g., a user of a hearing device, a candidate for a hearing device, and/or any other person for whom it may be desired to determine a hearing capability). The spectro-temporally modulated audio signal may be modulated simultaneously within both the frequency domain and the time domain. The processor may be further configured to execute the instructions to adjust a modulation depth of the spectro-temporally modulated audio signal while the spectro-temporally modulated audio signal is being presented to the user, determine, during the adjusting of the modulation depth, a modulation detection threshold that corresponds to a minimum modulation depth at which the user is able to perceive modulation of the spectro-temporally modulated audio signal, and determine, based on the modulation detection threshold, a hearing capability of the user. As will be described herein, the hearing capability of the user may correspond to a spectral sensitivity of the user within a frequency range associated with the spectro-temporally modulated audio signal. Additionally or alternatively, the hearing capability of the user may correspond to one or more hearing thresholds of the user that may be estimated based on the modulation detection threshold. 
     As used herein, a “spectro-temporally modulated audio signal” may refer to any suitable audio signal that is modulated simultaneously both in a frequency domain and a time domain. A spectro-temporally modulated audio signal may implement any suitable carrier noise to which modulation may be applied (e.g., multiplied). For example, the carrier noise may be white noise, pink noise, and/or any other suitable form of tone complex. A modulation depth of a spectro-temporally modulated audio signal may be adjusted in any suitable manner such as described herein to facilitate determining of a modulation detection threshold. As used herein, a “modulation detection threshold” corresponds to a minimum modulation depth at which a user is able to perceive modulation of the spectro-temporally modulated audio signal. At a modulation depth higher than the modulation detection threshold, the user is able to perceive the characteristic modulation of the spectro-temporally modulated audio signal. However, at a modulation depth less than the modulation detection threshold, the user is only able to perceive the spectro-temporally modulated audio signal as constant noise. As such, spectro-temporally modulated audio signals such as those described herein are different than audio signals used in pure-tone audiometry where a loudness level of the audio signals is adjusted to determine hearing thresholds of a user. Specific examples of spectro-temporally modulated audio signals are described herein. 
     By providing hearing evaluation systems and methods such as those described herein, it is possible to provide improved individualized fitting (e.g., improved frequency lowering, improved gain adjustment, etc.) of a hearing device to a user based on spectral sensitivity. In addition, the methods and systems described herein provide a simple and fast process to determine spectral sensitivity that is feasibly implemented in the everyday practice of a hearing care professional such as an audiologist or the like at a hearing device fitting facility. Moreover, with the hearing evaluation systems and methods described herein, it could be possible to detect and address hidden hearing loss and/or other hearing characteristics that are not otherwise discernable solely by pure-tone audiometry. For example, with the hearing evaluation systems and methods described herein, it may be possible to use modulation detection thresholds to estimate one or more hearing thresholds of a user in circumstances (e.g., loud hearing environments) where using pure-tone audiometry to determine such hearing thresholds is not feasible. Other benefits of the hearing evaluation systems and methods described herein will be made apparent herein. 
     As will be described further herein, hearing evaluation systems and methods such as those described herein may be used to more accurately fit a hearing device to a user as compared to known fitting systems. As used herein, a “hearing device” may be implemented by any device configured to provide or enhance hearing to a user. For example, a hearing device may be implemented by a hearing aid configured to amplify audio content to a user, a sound processor included in a cochlear implant system configured to apply electrical stimulation representative of audio content to a user, a sound processor included in a stimulation system configured to apply electrical and acoustic stimulation to a user, or any other suitable hearing prosthesis or combination of hearing prostheses. In some examples, a hearing device may be implemented by a behind-the-ear (“BTE”) component configured to be worn behind an ear of a user. In some examples, a hearing device may be implemented by an in-the-ear (“ITE”) component configured to at least partially be inserted within an ear canal of a user. In some examples, a hearing device may include a combination of an ITE component, a BTE component, and/or any other suitable component. 
       FIG. 1  illustrates an exemplary hearing evaluation system  100  (“system  100 ”) that may be implemented according to principles described herein. As shown, system  100  may include, without limitation, a memory  102  and a processor  104  selectively and communicatively coupled to one another. Memory  102  and processor  104  may each include or be implemented by hardware and/or software components (e.g., processors, memories, communication interfaces, instructions stored in memory for execution by the processors, etc.). 
     Memory  102  may maintain (e.g., store) executable data used by processor  104  to perform any of the operations associated with implementing a spectro-temporally modulated audio signal. For example, memory  102  may store instructions  106  that may be executed by processor  104  to perform any of the operations associated with system  100  described herein. Instructions  106  may be implemented by any suitable application, software, code, and/or other executable data instance. 
     Memory  102  may also maintain any data received, generated, managed, used, and/or transmitted by processor  104 . For example, memory  102  may maintain hearing characteristic data  108  that may be representative of any information associated with hearing loss characteristics of a user of a hearing device (e.g., hearing profiles, hearing thresholds, modulation detection thresholds, etc.). Memory  102  may also maintain additional data including, but not limited to, user interface information, notification information, spectro-temporally modulated audio signal information, and/or any other suitable information. In addition, memory  102  may maintain any data suitable to facilitate communications (e.g., wired and/or wireless communications) between system  100  and a hearing device, such as those described herein. Memory  102  may maintain additional or alternative data in other implementations. 
     Processor  104  may be configured to perform (e.g., execute instructions  106  stored in memory  102  to perform) various processing operations associated with implementing a spectro-temporally modulated audio signal. Such processing operations may include presenting a spectro-temporally modulated audio signal to a user, adjusting a modulation depth of the spectro-temporally modulated audio signal while the spectro-temporally modulated audio signal is being presented to the user, determining, during the adjusting of the modulation depth, a modulation detection threshold that corresponds to a minimum modulation depth at which the user is able to perceive modulation of the spectro-temporally modulated audio signal, and determining, based on the modulation detection threshold, a hearing capability of the user. These and other operations that may be performed by system  100  are described herein. 
     System  100  may be implemented in any suitable manner as may serve a particular implementation. For example, system  100  may be implemented by one or more computing devices capable of presenting spectro-temporally modulated signals (“STMs”) to a user (e.g., directly or by way of a speaker or receiver). To illustrate, system  100  may be implemented by a personal computer, a mobile device (e.g., a mobile phone configured to execute a mobile application that facilitates hearing capability evaluation), any of the hearing devices described herein, etc. In some examples, system  100  may be implemented at a clinician facility where an audiologist or the like uses system  100  to evaluate hearing loss characteristics of a user and uses those hearing loss characteristics to fit a hearing device to the user. 
       FIG. 2  shows an exemplary configuration  200  in which system  100  may be implemented. As shown in  FIG. 2 , system  100  may be provided in relation to a user  202  so as to present a spectro-temporally modulated (“STM”) audio signal  204  to a user  202 . To that end, system  100  may include or otherwise be communicatively connected to any suitable device configured to present audio content to user  202 . For example, system  100  may include or otherwise be communicatively connected to a speaker (not shown) (e.g., an audiometer headphone, a loudspeaker, etc.) configured to present STM audio signal  204  to user  202 . Additionally or alternatively, system  100  may direct a hearing device in any suitable manner to present (e.g., by way of a receiver of an ITE component) STM audio signal  204  to user  202  in certain implementations. 
     The audio characteristics of STM audio signal  204  may be defined in any suitable manner as may serve a particular implementation. Parameters used to define STM audio signal  204  may include, for example, a sampling rate parameter, a stimulus length parameter, a temporal modulation frequency parameter, a spectral modulation parameter (e.g., cycles/octave), a modulation depth parameter, a center frequency parameter, a bandwidth parameter, high and low cut off frequency parameters, and/or any other suitable parameter. System  100  may facilitate adjustment of such parameters in any suitable manner. For example, system  100  may provide one or more graphical user interfaces to facilitate a user (e.g., a clinician) adjusting one or more of such parameters to define STM audio signal  204  during a fitting procedure. 
     STM audio signal  204  may correspond to a broadband frequency range and may be spectrally modulated across any suitable range of the broadband frequency range. In certain examples, STM audio signal  204  may correspond to a broadband frequency range and may be spectrally modulated across the broadband frequency range. For example, STM audio signal  204  may be modulated substantially across an entire broadband frequency range (e.g., from 0 Hz to 15 kHz). In such examples, a modulation detection threshold determined based on STM audio signal  204  may correspond to a broadband modulation detection threshold. Such a broadband modulation detection threshold may be indicative of the hearing capability (e.g., spectral sensitivity and/or hearing thresholds) of user  202  with respect to the broadband frequency range. In addition, such a broadband modulation detection threshold may be used as an indicator for a maximum spectral sensitivity of the hearing of user  202  and may be used to estimate training effects. 
     In certain implementations, STM audio signal  204  may correspond to a broadband frequency range but may be modulated across only a sub-band frequency range within the broadband frequency range. STM audio signal  204  may be modulated across any suitable sub-band frequency range as may serve a particular implementation. For example, in certain implementations, the sub-band frequency range may be a one octave frequency band, a two octave frequency band, a three octave frequency band, a four octave frequency band, or any other suitable sub-band frequency range. In examples where STM audio signal  204  is modulated across a sub-band frequency range, the modulation detection threshold may be specific to the sub-band frequency range. In addition, the modulation detection threshold associated with a sub-band frequency range may be indicative of the hearing capability (e.g., spectral sensitivity and/or hearing thresholds) of user  202  with respect to the sub-band frequency range. 
       FIG. 3  shows an exemplary graphical depiction  302  that illustrates audio characteristics that STM audio signal  204  may have in certain implementations. As shown in  FIG. 3 , STM audio signal  204  may be modulated across a frequency domain shown along the y-axis and a time domain shown along the x-axis. In the example shown in FIG.  3 , the following parameters are set for STM audio signal  204 : a sampling frequency of 48000 Hz; a stimulation length 1 second; a temporal modulation frequency of 4 Hz; a spectral modulation of 2 cycles per octave; a modulation depth of 0 dB; a center frequency of 2000 Hz; a bandwidth of 4 octaves, a low cut off frequency of 500 Hz; and a high cut off frequency of 8000 Hz. 
     In the example shown in  FIG. 3 , STM audio signal is modulated across a sub-band frequency range  304  (as defined by low cut off frequency of 500 Hz and the high cut off frequency of 8000 Hz) within a broadband frequency range  306  of 0-15 kHz. STM audio signal  204  includes dark regions  308  and light regions  310  that are represented within sub-band frequency range  304 . Dark regions  308  represent relatively higher intensity regions of STM audio signal  204  and light regions  310  represent relatively lower intensity regions of STM audio signal  204 . Adjusting the modulation depth of STM audio signal  204  changes the relative intensity between the high intensity regions and the low intensity regions, thus making the modulation of STM audio signal  204  either easier for user  202  to perceive or more difficult for user  202  to perceive. To illustrate an example, the modulation depth of 0 dB in the example shown in  FIG. 3  may be decreased, for example, to −10 dB. Such a change is illustrated in  FIG. 4 , which shows a graphical depiction  402  that includes dark regions  404  and light regions  406  within sub-band frequency range  304 . As shown in  FIG. 4 , dark regions  404  are less pronounced as compared to dark regions  308  shown in  FIG. 3  illustrating that the −10 dB modulation is less than that depicted in  FIG. 3  and as a result the modulation represented in  FIG. 4  may be more difficult for user  202  to perceive. 
       FIG. 5  shows an exemplary flowchart  500  that depicts operations that may be performed by system  100  (e.g., processor  104 ) according to principles described herein. As shown in  FIG. 5 , at operation  502  system  100  may present STM audio signal  204  to user  202 . This may be performed in any suitable manner such as described herein. While STM audio signal  204  is presented to user  202 , system  100  may adjust a modulation depth of STM audio signal  204 . In certain examples, system  100  may adjust the modulation depth in response to an input provided by a clinician (e.g., by way of a graphical user interface). In certain alternative examples, system  100  may automatically adjust the modulation depth. As used herein, the expression “automatically” means that an operation (e.g., adjusting one or more parameters) or series of operations are performed without requiring further input from a user. 
     During adjustment of the modulation depth, system  100  may determine whether a modulation detection threshold has been reached at operation  506 . This may be accomplished in any suitable manner. For example, system  100  may instruct user  202  in any suitable manner to indicate whether user  202  is able to perceive modulation of STM audio signal  204 . System  100  may then receive subjective feedback from user  202  in the form of a communication indicating that user  202  is able to perceive the modulation of STM audio signal  204 . To illustrate an example, system  100  may present an audio clip (e.g., by way of a headphone speaker) instructing user  202  to, for example, say “YES,” raise a hand, and/or provide any other suitable communication to indicate that user  202  perceives the modulation. Based on the communication provided by user  202 , system  100  may determine whether the modulation detection threshold has been reached. 
     If the answer at operation  506  is “NO,” the process returns to before operation  504  and the modulation depth is adjusted again. System  100  may then perform operation  506  again to determine whether the modulation detection threshold has been determined at the adjusted modulation depth. This process may be repeated as many times as necessary until the modulation detection threshold is determined. 
     In certain examples, system  100  may adjust the modulation depth until user  202  perceives the modulation. For example, system  100  may initially set the modulation depth at a value that at which user  202  would not be able to perceive the modulation. System  100  may then facilitate incrementally increasing the modulation depth by any suitable amount until user  202  perceives the modulation. Alternatively, system  100  may adjust the modulation depth until user  202  stops perceiving the modulation. For example, system  100  may initially set the modulation depth at a value that at which user  202  would be able to perceive the modulation. System  100  may then facilitate incrementally decreasing the modulation depth by any suitable amount until user  202  begins perceiving the modulation. 
     If the answer at operation  506  is “YES,” system  100  may determine a hearing capability (e.g., an individual spectral sensitivity and/or hearing thresholds) of user  202  based on the modulation detection threshold at operation  508 . System  100  may determine the hearing capability of user  202  based on the modulation detection threshold in any suitable manner. For example, system  100  may compare the modulation detection threshold determined at operation  506  to one or more modulation detection thresholds of a person that has normal hearing characteristics within a frequency range associated with STM audio signal  204 . In so doing, system  100  may facilitate defining frequency regions with relatively higher or lower spectral sensitivity and estimating the frequency dependent spectral sensitivity (also referred to as a frequency dependent resolution capability) of user  202  within those frequency regions. 
     System  100  may perform operations  502  through  508  any suitable number of times for different frequency ranges of a broadband frequency range. For example, system  100  may perform operations  502 - 508  for a broadband frequency range to determine a broadband modulation detection threshold. Additionally or alternatively, system  100  may perform operations  502  through  508  for any suitable number of sub-band frequency ranges included in a broadband frequency range. For example, system  100  may perform operations  502  through  508  for each of a broadband frequency range, a first sub-band frequency range included in a broadband frequency range, a second sub-band frequency range included in the broadband frequency range, and a third sub-band frequency range included in the broadband frequency range. The first, second, and third sub-band frequency ranges may each correspond to different sub-band frequency ranges within the broadband frequency range. 
     In certain examples, each sub-band frequency range may have the same size. For example, the first, the second, and the third sub-band frequency ranges in the example described above may each have a width of one octave. In such examples, each sub-band frequency range may correspond to a different one octave frequency band within the broadband frequency range. Alternatively, at least some of the sub-band frequency ranges may have different sizes. For example, the first sub-band frequency range may correspond to a four octave frequency band, and the second and third sub-band frequency ranges may correspond to different one octave frequency bands within the broadband frequency range. 
     In certain examples, system  100  may perform operations  502  through  508  any suitable number of times for progressively more narrow sub-band frequency ranges included in the broadband frequency range. In so doing, system  100  may facilitate increasing the frequency resolution of the measurement of the hearing capability of user  202  within certain target frequency regions of interest. 
     In certain examples, system  100  may select a sub-band frequency range to use to determine a modulation detection threshold based on a hearing profile (e.g., an audiogram) of user  202 . Such a hearing profile may provide information regarding individual hearing thresholds and loudness comfort levels specific to user  202 . To that end, system  100  may obtain a hearing profile of user  202  in any suitable manner. For example, in certain implementations system  100  may access a hearing profile that is already generated for user  202  from any suitable source. Alternatively, system  100  may facilitate generating a hearing profile for user  202  in any suitable manner. 
     As a result of repeating operations  502 - 508 , system  100  may determine a broadband modulation detection threshold and one or more sub-band modulation detection thresholds. By determining both a broadband modulation detection threshold and one or more sub-band modulation detection thresholds (e.g., one octave modulation detection thresholds), it is possible to estimate the frequency dependent spectral sensitivity of user  202  relative to the determined modulation detection thresholds. This is advantageous in that systems and methods such as those described herein may be used without a training session and still provide feasible results. 
     In certain examples, operation  508  shown in  FIG. 5  may include system  100  adding information associated with one or more modulation detection thresholds determined by way of operations  502 - 508  to a hearing profile of user  202 . Such an addition may result in system  100  generating an augmented hearing profile that includes both hearing threshold data (e.g., generated based on pure-tone audiometry) and modulation detection threshold data (e.g., generated according to principles described herein). 
     To illustrate,  FIG. 6  shows an exemplary augmented hearing profile  600  that may be generated by system  100  according to principles described herein and may be provided for display during a fitting procedure. As shown in  FIG. 6 , hearing threshold in decibels (HL) is represented on the left side y-axis, frequency in Hz is represented along the x-axis, and modulation depth (MD) in decibels is represented along the right side y-axis.  FIG. 6  includes a plurality indicators  602  (e.g., indicators  602 - 1  through  602 - 10 ) that each represent different determined modulation detection thresholds for user  202  at different frequencies. Although  FIG. 6  shows ten indicators  602 , it is understood that any suitable number of indicators representing modulation detection thresholds may be depicted in an augmented hearing profile as may serve a particular implementation. 
     Line  604  in  FIG. 6  represents hearing thresholds for user  202  at different frequencies. The hearing threshold values represented by line  604  may be determined in any suitable manner using pure-tone audiometry. Dashed line  606  represents half of a broadband modulation detection threshold. 
     In the example shown in  FIG. 6 , an “R” is provided at the upper left corner of augmented hearing profile  600 . The “R” indicates that augmented hearing profile  600  is specific to the hearing loss characteristics of the right ear of user  202 . It is understood that system  100  may additionally or alternatively generate another augmented hearing profile that is specific to hearing loss characteristics of the left ear of user  202  and that may be separately provided for display during a fitting procedure. Alternatively, such hearing loss characteristics for the left ear may be provided for display together with the hearing loss characteristics of the right ear in augmented hearing profile  600 . 
     Returning to  FIG. 5 , at operation  510 , system  100  may fit a hearing device  512  to user  202  based on the hearing capability (e.g., individual spectral sensitivity and/or hearing thresholds) determined at operation  508 . Although only one hearing device  512  is shown in  FIG. 5 , it is understood that hearing device  512  may be included in a system that includes more than one hearing device configured to provide or enhance hearing to a user. For example, hearing device  512  may be included in a binaural hearing system that includes two hearing devices, one for each ear. In such examples, hearing device  512  may be provided behind, for example, the left ear of the user and an additional hearing device may be provided behind the right ear of the user. When hearing device  512  is included as part of a binaural hearing system, hearing device  512  may communicate with the additional hearing device by way of a binaural communication link that interconnects hearing device  512  with the additional hearing device. Such a binaural communication link may include any suitable wireless or wired communication link as may serve a particular implementation. 
     System  100  may fit hearing device  512  to user  202  in any suitable manner. For example, according to principles described herein, system  100  may facilitate determining the individual frequency dependent spectral sensitivity of user  202 . System  100  may then use the individual frequency dependent spectral sensitivity to adjust one or more fitting parameters of hearing device  512  for any suitable number of different frequency regions. To illustrate, system  100  may determine that user  202  has a first spectral sensitivity in a first frequency region, a second spectral sensitivity in a second frequency region, and a third spectral sensitivity in a third frequency region. System  100  may adjust one or more fitting parameters of hearing device  512  with respect to the first frequency region based on the first spectral sensitivity. Likewise, system  100  may adjust one or more fitting parameters of hearing device  512  with respect to the second and third frequency regions based on the second and third spectral sensitivities. As such, system  100  may specifically individualize fitting of hearing device  512  to user  202  in different frequency regions based on the individual frequency dependent spectral sensitivity of user  202 .  FIG. 7  shows an exemplary fitting workflow  700  depicting fitting operations that may be performed by system  100  according to principles described herein. As shown in  FIG. 7 , workflow block  702  represents an indication regarding the individual hearing loss of user  202 . 
     Workflow block  704  represents a basic diagnostic operation that includes acquiring (e.g., generating or obtaining from any suitable source) a hearing profile that is specific to user  202  and that is generated based on pure-tone audiometry. 
     Workflow block  706  represents an advanced diagnostic operation in which individual spectral sensitivity of user  202  is measured by using an STM audio signal (e.g., STM audio signal  204 ) in any suitable manner such as described herein. 
     Workflow block  708  represents a precalculated fitting operation that may be performed by system  100  based on both the individual hearing thresholds and the individual spectral sensitivity of user  202 . 
     Workflow block  710  represents a fitting operation in which hearing device  512  is fit to user  202  based on the individual hearing thresholds and individual spectral sensitivity of user  202 . 
     Workflow block  712  represents a frequency lowering algorithm that may be applied in certain examples to fit hearing device  512  to user  202 . Such a frequency lowering algorithm may be used to restore audibility of high frequencies for a user. To accomplished this, frequency lowering algorithms are generally configured to map higher frequencies, that are predicted to be inaudible to a user, to lower frequencies that are predicted to be audible. System  100  may implement any suitable type of frequency lowering algorithm as may serve a particular implementation. Exemplary types of frequency lowering algorithms may include non-linear frequency compression, adaptive non-linear frequency compression, linear frequency compression, frequency transposition, frequency composition, dynamic spectral identification and translation, or any other suitable type frequency lowering algorithm. 
     In certain examples, system  100  may modify a frequency lowering algorithm based on the individual hearing threshold and/or the individual spectral sensitivity of user  202 . For example, system  100  may obtain a hearing profile of user  202  in any suitable manner. Based on the hearing profile, system  100  may determine a frequency region of an input audio signal and/or an output audio signal to be subjected to the frequency lowering algorithm. System  100  may then adjust a parameter of the frequency lowering algorithm based on one or more modulation detection thresholds determined at workflow block  706 . 
     System  100  may adjust any suitable parameter of the frequency lowering algorithm based on the one or more modulation detection thresholds as may serve a particular implementation. For example, system  100  may adjust or change a target frequency region of an output audio signal to be subjected to the frequency lowering algorithm in any suitable manner based on the individual frequency dependent spectral sensitivity of user  202 . In certain examples, system  100  may adjust the frequency lowering algorithm such that the frequency lowering algorithm acts stronger or is more aggressive when a target frequency region shows a relatively high spectral sensitivity. On the other hand, when the spectral sensitivity in a target frequency region is relatively low, system  100  may reduce a compression ratio/amount of frequency mapping, increase a start frequency and work with a stronger amplification of mapped frequencies in a source region instead, and/or shift a target frequency region to even lower frequencies where spectral sensitivity may be higher. 
     Workflow block  714  represents a gain model that may be additionally or alternatively applied to at least part of the broadband frequency range based on the individual hearing threshold and/or the individual spectral sensitivity of user  202 . In such examples, system  100  may adjust, based on one or more modulation detection thresholds determined at workflow block  706 , a parameter of the gain model implemented by a hearing device to facilitate fitting the hearing device to user  202 . System  100  may adjust a parameter of the gain model in any suitable manner as may serve a particular implementation. For example, system  100  may implement the gain model more aggressively in certain target frequency regions having high spectral sensitivity thereby increasing resolution of the dynamic range for the hearing impaired. 
     Workflow block  716  represents a complete individualized fitting of a hearing device to user  202  based on workflow block  710  and, in certain examples, one or more of workflow blocks  712  and  714 . 
     In certain examples, the individual spectral sensitivity measured at workflow block  706  may be useful to detect hidden hearing loss of user  202 . In certain examples, such hidden hearing loss may be caused due to damage to inner and/or outer hair cells and nerve fibers of user  202 . For example, the inner hair cells of user  202  may be partially damaged in a particular frequency region. Such damage may not be discernable from the hearing thresholds of user  202  indicated in a hearing profile (e.g., an audiogram) because neighboring auditory filters may mask the damage in the frequency region. However, a relatively higher modulation detection threshold than is normal in the frequency region may be indicative of the damage and may be used to detect the hidden hearing loss. By detecting such hidden hearing loss, it is possible to detect slight hearing loss earlier than may otherwise be possible. This may result in an earlier decision by user  202  to seek help from a hearing care professional, which is beneficial because the earlier a hearing impaired person decides to get a hearing device, the better the hearing impaired person is able to adapt to and use the hearing device. 
     Additionally or alternatively, the individual spectral sensitivity measured at workflow block  706  may be useful to provide an estimation regarding particular damage to inner and/or outer hair cells of user  202 . For example, a reduced spectral sensitivity when the sound itself is still perceivable at a moderate stimulus level could indicate that the hearing loss is mainly caused by damaged inner hair cells. However, a high or normal spectral sensitivity at loud stimulus levels but an increased hearing threshold could indicate damaged outer hair cells but mainly intact inner hair cells. This would allow an estimation of whether a simple amplification of a sound is enough for user  202  or whether adjusting one or more other fitting parameters would be useful. Such an estimation could also help in evaluating whether user  202  should receive a cochlear implant or not and whether any respective parts of the cochlear implant should be omitted from an implanted electrode to conserve residual hearing of user  202 . 
     In examples where hearing device  512  corresponds to a cochlear implant, system  100  may additionally or alternatively use the individual spectral sensitivity determined at workflow block  706  to estimate a quality of connection of a cochlear implant electrode to an auditory nerve. For example, one or more modulation detection thresholds such as those described herein may provide information regarding which frequency regions of the cochlear implant electrode have a good connection to the auditory nerve. System  100  may then use such information in any suitable manner to fine tune fitting of the cochlear implant to user  202 . 
     In certain examples, the hearing capability of a user may additionally or alternatively correspond to one or more hearing thresholds of the user. This is possible based on a correlation that exists between modulation detection thresholds such as those described herein and hearing thresholds of a user. A modulation detection threshold may be correlated with a hearing threshold in any suitable manner. For example, a modulation detection threshold below a predefined value within a certain sub-band frequency range may be indicative of the user having a hearing threshold below a predefined value within that sub-band frequency range, which may be indicative of hearing loss. In such examples, system  100  may additionally or alternatively be configured to estimate one or more hearing thresholds of a user based on one or more modulation detection thresholds. Estimating hearing thresholds based on modulation thresholds may be beneficial in circumstances where it is not possible to measure such hearing thresholds in a conventional way (e.g., by using pure-tone audiometry). For example, in noisy environments (e.g., in public places, at home, at work, etc.) where browser-based or application-based hearing screenings may be performed, the background noise may make it difficult or impossible to use audio tones to adequately detect hearing thresholds. However, modulation detection thresholds such as those described herein may be independent of presentation level as long as the modulation carrier noise is perceivable. Accordingly, in such circumstances, system  100  may be configured to estimate a hearing threshold of a user based on a determined modulation detection threshold. 
     In certain examples, the estimation of a hearing threshold based on a modulation detection threshold may correspond to a preliminary or rough estimate of potential hearing loss of the user. In such examples, system  100  may provide a notification to the user in any suitable manner that informs the user of the potential hearing loss and instructs the user to schedule a hearing test with a hearing care professional such as an audiologist or the like at a hearing device fitting facility. 
     The preceding disclosure describes adjusting modulation depth of an STM audio signal to facilitate determining a modulation detection threshold. In such examples, other parameters (e.g., the bandwidth, low and high cut off frequencies, etc.) used to define the STM audio signal may be fixed while the modulation depth is adjusted. However, it is understood that different parameters may be adjusted while other parameters are fixed in other implementations. For example, in certain alternative implementations, the bandwidth may be varied at a fixed modulation depth. In such examples, the modulation detection threshold may depend on the adjusted bandwidth instead of the adjusted modulation depth. 
       FIG. 8  illustrates an exemplary method  800  for implementing a spectro-temporally modulated audio signal. While  FIG. 8  illustrates exemplary operations according to one embodiment, other embodiments may omit, add to, reorder, and/or modify any of the operations shown in  FIG. 8 . One or more of the operations shown in  FIG. 8  may be performed by a hearing evaluation system such as hearing evaluation system  100 , any components included therein, and/or any implementation thereof. 
     At operation  802 , a processor (e.g., processor  104 ) may present a spectro-temporally modulated audio signal to a user (e.g., user  202 ). As described herein the spectro-temporally modulated audio signal may be modulated in both a frequency domain and a time domain. Operation  802  may be performed in any of the ways described herein. For example, the spectro-temporally modulated audio signal may be presented to the user with a modulation depth specified by a clinician and/or hearing evaluation system  100 . 
     At operation  804 , the processor may adjust a modulation depth of the spectro-temporally modulated audio signal while the spectro-temporally modulated audio signal is being presented to the user. Operation  804  may be performed in any of the ways described herein. 
     At operation  806 , the processor may determine, during the adjusting of the modulation depth, a modulation detection threshold that corresponds to a minimum modulation depth at which the user is able to perceive modulation of the spectro-temporally modulated audio signal. Operation  806  may be performed in any of the ways described herein. 
     At operation  808 , the processor may determine, based on the modulation detection threshold, a hearing capability of the user. For example, the processor may determine a frequency dependent spectral sensitivity of the user based on the modulation detection threshold. Operation  808  may be performed in any of the ways described herein. 
     In some examples, a non-transitory computer-readable medium storing computer-readable instructions may be provided in accordance with the principles described herein. The instructions, when executed by a processor of a computing device, may direct the processor and/or computing device to perform one or more operations, including one or more of the operations described herein. Such instructions may be stored and/or transmitted using any of a variety of known computer-readable media. 
     A non-transitory computer-readable medium as referred to herein may include any non-transitory storage medium that participates in providing data (e.g., instructions) that may be read and/or executed by a computing device (e.g., by a processor of a computing device). For example, a non-transitory computer-readable medium may include, but is not limited to, any combination of non-volatile storage media and/or volatile storage media. Exemplary non-volatile storage media include, but are not limited to, read-only memory, flash memory, a solid-state drive, a magnetic storage device (e.g. a hard disk, a floppy disk, magnetic tape, etc.), ferroelectric random-access memory (“RAM”), and an optical disc (e.g., a compact disc, a digital video disc, a Blu-ray disc, etc.). Exemplary volatile storage media include, but are not limited to, RAM (e.g., dynamic RAM). 
       FIG. 9  illustrates an exemplary computing device  900  that may be specifically configured to perform one or more of the processes described herein. As shown in  FIG. 9 , computing device  900  may include a communication interface  902 , a processor  904 , a storage device  906 , and an input/output (“I/O”) module  908  communicatively connected one to another via a communication infrastructure  910 . While an exemplary computing device  900  is shown in  FIG. 9 , the components illustrated in  FIG. 9  are not intended to be limiting. Additional or alternative components may be used in other embodiments. Components of computing device  900  shown in  FIG. 9  will now be described in additional detail. 
     Communication interface  902  may be configured to communicate with one or more computing devices. Examples of communication interface  902  include, without limitation, a wired network interface (such as a network interface card), a wireless network interface (such as a wireless network interface card), a modem, an audio/video connection, and any other suitable interface. 
     Processor  904  generally represents any type or form of processing unit capable of processing data and/or interpreting, executing, and/or directing execution of one or more of the instructions, processes, and/or operations described herein. Processor  904  may perform operations by executing computer-executable instructions  912  (e.g., an application, software, code, and/or other executable data instance) stored in storage device  906 . 
     Storage device  906  may include one or more data storage media, devices, or configurations and may employ any type, form, and combination of data storage media and/or device. For example, storage device  906  may include, but is not limited to, any combination of the non-volatile media and/or volatile media described herein. Electronic data, including data described herein, may be temporarily and/or permanently stored in storage device  906 . For example, data representative of computer-executable instructions  912  configured to direct processor  904  to perform any of the operations described herein may be stored within storage device  906 . In some examples, data may be arranged in one or more databases residing within storage device  906 . 
     I/O module  908  may include one or more I/O modules configured to receive user input and provide user output. I/O module  908  may include any hardware, firmware, software, or combination thereof supportive of input and output capabilities. For example, I/O module  908  may include hardware and/or software for capturing user input, including, but not limited to, a keyboard or keypad, a touchscreen component (e.g., touchscreen display), a receiver (e.g., an RF or infrared receiver), motion sensors, and/or one or more input buttons. 
     I/O module  908  may include one or more devices for presenting output to a user, including, but not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display drivers), one or more audio speakers, and one or more audio drivers. In certain embodiments, I/O module  908  is configured to provide graphical data to a display for presentation to a user. The graphical data may be representative of one or more graphical user interfaces and/or any other graphical content as may serve a particular implementation. 
     In some examples, any of the systems, hearing devices, and/or other components described herein may be implemented by computing device  900 . For example, memory  102  may be implemented by storage device  906 , and processor  104  may be implemented by processor  904 . 
     In the preceding description, various exemplary embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the claims that follow. For example, certain features of one embodiment described herein may be combined with or substituted for features of another embodiment described herein. The description and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.