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Eric D. Young - One of the best experts on this subject based on the ideXlab platform.
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encoding intensity in ventral cochlear nucleus following acoustic trauma implications for Loudness Recruitment
Jaro-journal of The Association for Research in Otolaryngology, 2009Co-Authors: Wei Li D, Eric D. YoungAbstract:Loudness Recruitment, an abnormally rapid growth of perceived Loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with Recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91–105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261–274, 2000), suggesting that Recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons’ responses to Recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to Loudness balance functions that show the sound levels giving equal perceptual Loudness in the two ears of a monaurally hearing-impaired person. The rate-balance functions showed Recruitment-like steepening of their slopes in non-primary-like neurons in all conditions. However, primary-like neurons showed Recruitment-like behavior only when rates were summated across neurons of all BFs. These results suggest that the non-primary-like, especially chopper, neurons may be the most peripheral site of the physiological changes in the brain that underlie Recruitment.
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Journal of the Association for Research in Otolaryngology Encoding Intensity in Ventral Cochlear Nucleus Following Acoustic Trauma: Implications for Loudness Recruitment
2008Co-Authors: Shanqing Cai, Wei Li D, Eric D. YoungAbstract:Loudness Recruitment, an abnormally rapid growth of perceived Loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with Recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91–105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261–274, 2000), suggesting that Recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons’ responses to Recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to Loudness balance functions that show the sound levels giving equal perceptual Loudness in the two ears of a monaurally hearing-impaired person. The ratebalance functions showed Recruitment-like steepenin
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auditory nerve rate responses are inconsistent with common hypotheses for the neural correlates of Loudness Recruitment
Jaro-journal of The Association for Research in Otolaryngology, 2005Co-Authors: Michael G. Heinz, Joh Issa, Eric D. YoungAbstract:A number of perceptual phenomena related to normal and impaired level coding can be accounted for by the degree of compression in the basilar-membrane (BM) magnitude response. However, the narrow dynamic ranges of auditory-nerve (AN) fibers complicate these arguments. Because the AN serves as an information bottleneck, an improved understanding of the neural coding of level may clarify some of the limitations of current hearing aids. Here three hypotheses for the neural correlate of Loudness Recruitment were evaluated based on AN responses from normal-hearing cats and from cats with a noise-induced hearing loss (NIHL). Auditory-nerve fiber rate-level functions for tones were analyzed to test the following hypotheses: Loudness Recruitment results from steeper AN rate functions after impairment. This hypothesis was not supported; AN rate functions were not steeper than normal following NIHL, despite steeper estimated BM responses based on the AN data. Loudness is based on the total AN discharge count, and Recruitment results from an abnormally rapid spread of excitation after impairment. Whereas abnormal spread of excitation can be observed, steeper growth of total AN rate is not seen over the range of sound levels where Recruitment is observed in human listeners. Loudness of a narrowband stimulus is based on AN responses in a narrow BF region, and Recruitment results from compression of the AN-fiber threshold distribution after impairment. This hypothesis was not supported because there was no evidence that impaired AN threshold distributions were compressed and the growth of AN activity summed across BFs near the stimulus frequency was shallower than normal.
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Auditory-Nerve Rate Responses are Inconsistent with Common Hypotheses for the Neural Correlates of Loudness Recruitment
Journal of the Association for Research in Otolaryngology, 2005Co-Authors: Michael G. Heinz, John B. Issa, Eric D. YoungAbstract:A number of perceptual phenomena related to normal and impaired level coding can be accounted for by the degree of compression in the basilar-membrane (BM) magnitude response. However, the narrow dynamic ranges of auditory-nerve (AN) fibers complicate these arguments. Because the AN serves as an information bottleneck, an improved understanding of the neural coding of level may clarify some of the limitations of current hearing aids. Here three hypotheses for the neural correlate of Loudness Recruitment were evaluated based on AN responses from normal-hearing cats and from cats with a noise-induced hearing loss (NIHL). Auditory-nerve fiber rate-level functions for tones were analyzed to test the following hypotheses: Loudness Recruitment results from steeper AN rate functions after impairment. This hypothesis was not supported; AN rate functions were not steeper than normal following NIHL, despite steeper estimated BM responses based on the AN data. Loudness is based on the total AN discharge count, and Recruitment results from an abnormally rapid spread of excitation after impairment. Whereas abnormal spread of excitation can be observed, steeper growth of total AN rate is not seen over the range of sound levels where Recruitment is observed in human listeners. Loudness of a narrowband stimulus is based on AN responses in a narrow BF region, and Recruitment results from compression of the AN-fiber threshold distribution after impairment. This hypothesis was not supported because there was no evidence that impaired AN threshold distributions were compressed and the growth of AN activity summed across BFs near the stimulus frequency was shallower than normal. Overall, these results suggest that Loudness Recruitment cannot be accounted for based on summed AN rate responses and may depend on neural mechanisms involved in the central representation of intensity.
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Physiological Modeling for Hearing Aid Design
2000Co-Authors: Ian Bruce Eric, Eric D. Young, Murray . SachsAbstract:Perceptual models of impaired hearing are being used increasingly in hearing aid design. The most successful application has been compression schemes to compensate for Loudness Recruitment. Less fruitful have been attempts to counteract degraded cochlear filtering with spectral shaping. Perceptual models are developed from psychophysical measures that reflect both peripheral and central processing. More physiological detail may be required to describe the effects of a cochlear lesion on peripheral coding of speech. For example, physiological data from hearing-impaired cats indicate that conventional hearing aid signal processing schemes do not restore normal auditory nerve responses to a vowel (Miller et al., JASA 101:3602, 1997) and can even produce anomalous and potentially confounding patterns of activity (Schilling et al., Hear. Res. 117:57, 1998). These deficits in the neural representation may at least partially account for poor speech perception in some hearing aid users. An amplification scheme has been developed that produces neural responses to a vowel more like those seen in normal cats and that minimizes confounding responses (Miller et al., JASA 106:2693, 1999). A physiological model of the normal and impaired auditory periphery would provide simpler and quicker testing of such potential hearing aid designs. Details of a physiological model will be presented. Model predictions of vowel responses suggest that degraded cochlear filtering can indeed account for a good deal of the data from hearingimpaired cats described above. However, some response properties appear to result from physiological features that are not considered in perceptual models. In particular, auditory nerve responses to speech stimuli are very sensitive to wide-band nonlinearities in the ..
Wei Li D - One of the best experts on this subject based on the ideXlab platform.
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encoding intensity in ventral cochlear nucleus following acoustic trauma implications for Loudness Recruitment
Jaro-journal of The Association for Research in Otolaryngology, 2009Co-Authors: Wei Li D, Eric D. YoungAbstract:Loudness Recruitment, an abnormally rapid growth of perceived Loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with Recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91–105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261–274, 2000), suggesting that Recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons’ responses to Recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to Loudness balance functions that show the sound levels giving equal perceptual Loudness in the two ears of a monaurally hearing-impaired person. The rate-balance functions showed Recruitment-like steepening of their slopes in non-primary-like neurons in all conditions. However, primary-like neurons showed Recruitment-like behavior only when rates were summated across neurons of all BFs. These results suggest that the non-primary-like, especially chopper, neurons may be the most peripheral site of the physiological changes in the brain that underlie Recruitment.
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Journal of the Association for Research in Otolaryngology Encoding Intensity in Ventral Cochlear Nucleus Following Acoustic Trauma: Implications for Loudness Recruitment
2008Co-Authors: Shanqing Cai, Wei Li D, Eric D. YoungAbstract:Loudness Recruitment, an abnormally rapid growth of perceived Loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with Recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91–105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261–274, 2000), suggesting that Recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons’ responses to Recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to Loudness balance functions that show the sound levels giving equal perceptual Loudness in the two ears of a monaurally hearing-impaired person. The ratebalance functions showed Recruitment-like steepenin
Brian C J Moore - One of the best experts on this subject based on the ideXlab platform.
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effect of the number of amplitude compression channels and compression speed on speech recognition by listeners with mild to moderate sensorineural hearing loss
Journal of the Acoustical Society of America, 2020Co-Authors: Marina Saloriocorbetto, Thomas Baer, Michael A Stone, Brian C J MooreAbstract:The use of a large number of amplitude-compression channels in hearing aids has potential advantages, such as the ability to compensate for variations in Loudness Recruitment across frequency and provide appropriate frequency-response shaping. However, sound quality and speech intelligibility could be adversely affected due to reduction of spectro-temporal contrast and distortion, especially when fast-acting compression is used. This study assessed the effect of the number of channels and compression speed on speech recognition when the multichannel processing was used solely to implement amplitude compression, and not for frequency-response shaping. Computer-simulated hearing aids were used. The frequency-dependent insertion gains for speech with a level of 65 dB sound pressure level were applied using a single filter before the signal was filtered into compression channels. Fast-acting (attack, 10 ms; release, 100 ms) or slow-acting (attack, 50 ms; release, 3000 ms) compression using 3, 6, 12, and 22 channels was applied subsequently. Using a sentence recognition task with speech in two- and eight-talker babble at three different signal-to-babble ratios (SBRs), 20 adults with sensorineural hearing loss were tested. The number of channels and compression speed had no significant effect on speech recognition, regardless of babble type or SBR.The use of a large number of amplitude-compression channels in hearing aids has potential advantages, such as the ability to compensate for variations in Loudness Recruitment across frequency and provide appropriate frequency-response shaping. However, sound quality and speech intelligibility could be adversely affected due to reduction of spectro-temporal contrast and distortion, especially when fast-acting compression is used. This study assessed the effect of the number of channels and compression speed on speech recognition when the multichannel processing was used solely to implement amplitude compression, and not for frequency-response shaping. Computer-simulated hearing aids were used. The frequency-dependent insertion gains for speech with a level of 65 dB sound pressure level were applied using a single filter before the signal was filtered into compression channels. Fast-acting (attack, 10 ms; release, 100 ms) or slow-acting (attack, 50 ms; release, 3000 ms) compression using 3, 6, 12, and 22 ch...
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psychoacoustics of normal and impaired hearing
British Medical Bulletin, 2002Co-Authors: Brian C J MooreAbstract:Recent developments in the field of psychoacoustics are presented, focusing on areas which have application in the diagnosis and understanding of impaired hearing. Cochlear hearing loss often results in a loss of the compressive nonlinearity that operates in normal ears; this loss is probably the main cause of Loudness Recruitment. Forward masking can be used as a tool to assess the strength of cochlear compression in human listeners. Hearing impairment can sometimes be associated with complete loss of function of inner hair cells over a certain region of the cochlea, resulting in a ‘dead region’. Two psychoacoustic methods for detecting dead regions and defining their limits are described. The implications of the results for fitting hearing aids are discussed. Finally, the effect of cochlear hearing loss on the perception of rapid sequences of sounds (stream segregation) is described. This chapter presents a selective review of recent developments in the field of psychoacoustics. It focuses on areas which have application in the diagnosis and understanding of impaired hearing. It does not repeat topics covered in my earlier British Medical Bulletin review 1 . For more comprehensive coverage of the psychoacoustics of impaired hearing, the reader is referred to reviews elsewhere 2,3 .
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psychoacoustics of cochlear hearing impairment and the design of hearing aids
Journal of the Acoustical Society of America, 1998Co-Authors: Brian C J MooreAbstract:Cochlear hearing impairment is usually associated with damage to the hair cells within the cochlea. When the damage is restricted to the outer hair cells (OHCs), the main consequence is disruption of the ‘‘active’’ mechanism which normally enhances the response of the basilar membrane to weak sounds and which sharpens the tuning (frequency selectivity) of the basilar membrane. Psychoacoustically, damage to OHCs results in loss of sensitivity (elevated absolute thresholds), Loudness Recruitment, and reduced frequency selectivity. Damage to the inner hair cells (IHCs) causes basilar membrane vibrations to be transduced less effectively, so absolute thresholds are elevated, but does not result in altered frequency selectivity or Loudness Recruitment. Sometimes, IHCs and/or neurons may be completely inoperative at certain places within the cochlea, giving rise to ‘‘dead regions.’’ Such regions can strongly influence the perception of pitch and Loudness. Current hearing aids can partially compensate for the effects of Loudness Recruitment by using compression amplification, but there is much controversy about the ‘‘best’’ form of compression. The deleterious effects of reduced frequency selectivity on speech intelligibility in noise can be alleviated by various methods for improving the speech‐to‐noise ratio, although so far only directional microphones have given clear benefits.
Ia C J Moore - One of the best experts on this subject based on the ideXlab platform.
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British Medical Bulletin 2002;63: 121–134 The British Council 2002 Psychoacoustics of normal and impaired hearing
2015Co-Authors: Ia C J MooreAbstract:Recent developments in the field of psychoacoustics are presented, focusing on areas which have application in the diagnosis and understanding of impaired hearing. Cochlear hearing loss often results in a loss of the compressive non-linearity that operates in normal ears; this loss is probably the main cause of Loudness Recruitment. Forward masking can be used as a tool to assess the strength of cochlear compression in human listeners. Hearing impairment can sometimes be associated with complete loss of function of inner hair cells over a certain region of the cochlea, resulting in a ‘dead region’. Two psychoacoustic methods for detecting dead regions and defining their limits are described. The implications of the results for fitting hearing aids are discussed. Finally, the effect of cochlear hearing loss on the perception of rapid sequences of sounds (stream segregation) is described. This chapter presents a selective review of recent developments in the field of psychoacoustics. It focuses on areas which have application in the diagnosis and understanding of impaired hearing. It does not repea
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Speech processing for the hearing-impaired: successes, failures, and implications for speech mechanisms
2014Co-Authors: Ia C J MooreAbstract:People with sensorineural hearing impairment typically have more difficulty than normally hearing people in un-derstanding speech in the presence of background sounds. This paper starts by quantifying the magnitude of the problem in various listening situations and with various types of background sound. It then considers some of the factors that contribute to this difficulty, including: reduced audibility; reduced frequency selectivity; Loudness recruit-ment; and regions in the cochlea which have no surviving inner hair cells and/or neurones (dead regions). Methods of compensating for the effects of some of these factors are described and evaluated. Signal-processing methods to compensate for the effects of reduced frequency selectivity using the output of a single microphone have had only limited success, although methods using multiple microphones have worked well. Amplitude compression can com-pensate for some of the effects of Loudness Recruitment, allowing speech to be understood over a wide range of sound levels. The exact form of the compression (fast-acting versus slow-acting, single-channel versus multiple channel) does not seem to be critical, suggesting that the relative Loudness of different components of speech, and dynamic aspects of Loudness perception do not need to be restored to ‘‘normal’’
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Psychoacoustics of normal and impaired hearing
2008Co-Authors: Ia C J MooreAbstract:Recent developments in the field of psychoacoustics are presented, focusing on areas which have application in the diagnosis and understanding of impaired hearing. Cochlear hearing loss often results in a loss of the compressive nonlinearity that operates in normal ears; this loss is probably the main cause of Loudness Recruitment. Forward masking can be used as a tool to assess the strength of cochlear compression in human listeners. Hearing impairment can sometimes be associated with complete loss of function of inner hair cells over a certain region of the cochlea, resulting in a ‘dead region’. Two psychoacoustic methods for detecting dead regions and defining their limits are described. The implications of the results for fitting hearing aids are discussed. Finally, the effect of cochlear hearing loss on the perception of rapid sequences of sounds (stream segregation) is described. This chapter presents a selective review of recent developments in the field of psychoacoustics. It focuses on areas which have application in the diagnosis and understanding of impaired hearing. It does not repeat topics covered in my earlier British Medical Bulletin review 1. For more comprehensive coverage of the psychoacoustics of impaired hearing, the reader is referred to reviews elsewhere 2,3. Using forward masking to assess cochlear compression Correspondence to
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simulation of the effect of threshold elevation and Loudness Recruitment combined with reduced frequency selectivity on the intelligibility of speech in noise
Journal of the Acoustical Society of America, 1997Co-Authors: Yoshito Nejime, Ia C J MooreAbstract:The effect of Loudness Recruitment and threshold elevation together with reduced frequency selectivity have been simulated to examine the combined effect of the two major consequences of cochlear hearing loss on the intelligibility of speech in speech-shaped noise. In experiment 1, four conditions were simulated: a moderate flat loss with auditory filters broadened by a factor of three (B3R2); a moderate-to-severe sloping loss with auditory filters broadened by a constant factor of three (B3RX); and these conditions with linear amplification applied prior to the simulation processing (B3R2+, B3RX+). For conditions B3R2 and B3RX, performance was markedly worse than for a control condition (normal hearing, condition R1) tested in a previous study. For conditions B3R2+ and B3RX+, linear amplification improved performance considerably. However, performance remained below that for condition R1 by between 5% and 19%. In experiment 2 the broadening of the auditory filters was made more realistic by making it a function of the absolute threshold at the center frequency of the auditory filter. Three different hearing losses were simulated: a moderate-to-severe sloping loss with variable broadening of the auditory filters (BXRX); the same moderate-to-severe sloping loss with linear amplification (BXRX+); and the same broadening of the auditory filters but without the simulation of Loudness Recruitment and threshold elevation (BX). For condition BXRX, performance was markedly worse than in condition R1, while performance in condition BX was somewhat worse than for condition R1. For condition BXRX+, linear amplification according to the NAL procedure improved performance to a large extent but it remained worse than for condition R1. The results are consistent with previous evidence indicating that only part of the decrease of performance produced by actual cochlear hearing loss can be compensated by conventional linear hearing aids.
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effect of Loudness Recruitment on the perception of amplitude modulation
Journal of the Acoustical Society of America, 1996Co-Authors: Ia C J Moore, Magdalena Wojtczak, Deborah VickersAbstract:People with hearing loss of cochlear origin usually display Loudness Recruitment; the rate of growth of Loudness level with increasing sound level is greater than for a normally hearing person. Loudness Recruitment has usually been studied with steady sounds of relatively long duration. The present study examines how Recruitment affects the perception of dynamically varying sounds, namely amplitude modulated sinusoids. The modulation rates used (4, 8, 16, and 32 Hz) were chosen to span the range of the most prominent modulations present in the envelope of speech. Three subjects with unilateral cochlear hearing loss were used. In experiment 1, subjects were required to make Loudness matches between 1‐kHz tones presented alternately to the two ears. This was done over a wide range of sound levels. Experiment 2 used 1‐kHz carriers that were amplitude modulated. The modulation was sinusoidal on a dB scale. The modulated tones were presented alternately to the two ears and were approximately equally loud in the two ears. The modulation depth was fixed in one ear, and the subject was required to adjust the modulation depth in the other ear so that the modulation depth appeared equal in the two ears. This was done for a range of modulation depths and with the fixed tone presented to both the normal and the impaired ear. A given modulation depth in the impaired ear was matched by a greater modulation depth in the normal ear. To a first approximation, the modulation‐matching functions were independent of modulation rate. Furthermore, the functions could be predicted reasonably well from the Loudness‐matching results of experiment 1, obtained with steady tones. The results are consistent with the idea that Loudness Recruitment results from the loss of a fast‐acting compressive nonlinearity that operates in the normal peripheral auditory system. Possible implications of the results for the use of fast‐acting compression in hearing aids are discussed.
Abee Alwa - One of the best experts on this subject based on the ideXlab platform.
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a novel structure to compensate for frequency dependent Loudness Recruitment of sensorineural hearing loss
International Conference on Acoustics Speech and Signal Processing, 1995Co-Authors: Ia Strope, Abee AlwaAbstract:A simple structure that compensates for frequency-dependent Loudness Recruitment of sensorineural hearing loss is presented. The non-linear structure estimates total input signal energy, and then weights and combines the output of two parallel filters based on this energy estimation. Preliminary evaluation of this structure with noise-masked normal hearing listeners, and speech recorded in naturally noisy environments, shows a 15-20% performance increase in word recognition scores when compared to a linear structure.
