Does the degree of linguistic experience (native versus nonnative) modulate the degree to which listeners can benefit from a delay between the onset of the maskers and the onset of the target speech?

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Boaz M. Ben-David, Meital Avivi-Reich, Bruce A. Schneider
Background noise has a greater adverse effect on word recognition when people are listening in their second language (L2) as opposed to their first language (L1). The present study investigates the extent to which linguistic experience affects the ability of L2 listeners to benefit from a delay between the onset of a masker and the onset of a word. In a previous study (Ben-David, Tse & Schneider, 2012), word recognition thresholds for young L1s were found to improve with the increase in the delay between the onset of a masker (either a stationary noise or a babble of voices) and the onset of a word. The investigators interpreted this result as reflecting the ability of L1 listeners to rapidly segregate the target words from a masker. Given stream segregation depends, in part, on top-down knowledge-driven processes, we might expect stream segregation to be more “sluggish” for L2 listeners than for L1 listeners, especially when the masker consists of a babble of L2 voices. In the present study, we compared the ability of native English speakers to those who had either recent or long-term immersion in English as L2, to benefit from a delay between masker onset and word onset for English words. Results show that thresholds were higher for the two L2s groups than for the L1s. However, the rate at which word recognition improved with word-onset delay was unaffected by linguistic status, both when words were presented in noise, and in babble. Hence, for young listeners, stream segregation appears to be independent of linguistic status, suggesting that bottom-up sensory mechanisms play a large role in stream segregation in this paradigm. The implications of a failure of older L1 listeners (in Ben-David et al.) to benefit from a word-onset delay when the masker is a babble of voices are discussed.



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Frequency discrimination in the common marmoset (Callithrix jacchus)

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Michael S. Osmanski, Xindong Song, Yueqi Guo, Xiaoqin Wang
The common marmoset (Callithrix jacchus) is a highly vocal New World primate species that has emerged in recent years as a promising model system for studies of auditory and vocal processing. Our recent studies have examined perceptual mechanisms related to the pitch of harmonic complex tones in this species. However, no previous psychoacoustic work has measured marmosets’ frequency discrimination abilities for pure tones across a broad frequency range. Here we systematically examined frequency difference limens (FDLs), which measure the minimum discriminable frequency difference between two pure tones, in marmosets across most of their hearing range. Results show that marmosets’ FDLs are comparable to other New World primates, with lowest values in the frequency range of ∼3.5–14 kHz. This region of lowest FDLs corresponds with the region of lowest hearing thresholds in this species measured in our previous study and also with the greatest concentration of spectral energy in the major types of marmoset vocalizations. These data suggest that frequency discrimination in the common marmoset may have evolved to match the hearing sensitivity and spectral characteristics of this species’ vocalizations.



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Controlled Exploration of the Effects of Conductive Hearing Loss on Wideband Acoustic Immittance in Human Cadaveric Preparations

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Gabrielle R. Merchant, Saumil N. Merchant, John J. Rosowski, Hideko Heidi Nakajima
Current clinical practice cannot distinguish, with any degree of certainty, the multiple pathologies that produce conductive hearing loss in patients with an intact tympanic membrane and a well-aerated middle ear without exploratory surgery. The lack of an effective non-surgical diagnostic procedure leads to unnecessary surgery and limits the accuracy of information available during pre-surgical consultations with the patient. A non-invasive measurement to determine the pathology responsible for a conductive hearing loss prior to surgery would be of great value. This work investigates the utility of wideband acoustic immittance (WAI), a non-invasive measure of middle-ear mobility, in the differential diagnosis of pathologies responsible for conductive hearing loss.We focus on determining whether power reflectance (PR), a derivative of WAI, is a possible solution to this problem. PR is a measure of the fraction of sound power reflected from the middle ear when a sound stimulus is presented to the ear canal. PR and other metrics of middle-ear performance (such as ossicular motion via laser Doppler vibrometry) were measured in well-controlled human temporal bone preparations with simulated pathologies. We report measurements before and after simulation of stapes fixation (n=8), malleus fixation (n=10), ossicular disarticulation (n=10), and superior canal dehiscence (n=8). Our results are consistent with the small set of previously published reflectance measurements made in temporal bones and patients. In this present study, these temporal bone experiments with different middle- and inner-ear pathologies were compared to the initial normal state by analyzing both WAI and ossicular motion, demonstrating that WAI can be a valuable tool in the diagnosis of conductive hearing loss.



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Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): N.P.M. Todd, S. Govender, J.G. Colebatch
Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.



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Drug discovery for hearing loss: Phenotypic screening of chemical compounds on primary cultures of the spiral ganglion

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Donna S. Whitlon
In the United States there are, at present, no drugs that are specifically FDA approved to treat hearing loss. Although several clinical trials are ongoing, including one testing D-methionine that is supported by the US Army, none of these trials directly address the effect of noise exposure on cochlear spiral ganglion neurons. We recently published the first report of a systematic chemical compound screen using primary, mammalian spiral ganglion cultures in which we were able to detect a compound and others in its class that increased neurite elongation, a critical step in restoring cochlear synapses after noise induced hearing loss. Here we discuss the issues, both pro and con, that influenced the development of our approach. These considerations may be useful for future compound screens that target the same or other attributes of cochlear spiral ganglion neurons.



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Does the degree of linguistic experience (native versus nonnative) modulate the degree to which listeners can benefit from a delay between the onset of the maskers and the onset of the target speech?

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Boaz M. Ben-David, Meital Avivi-Reich, Bruce A. Schneider
Background noise has a greater adverse effect on word recognition when people are listening in their second language (L2) as opposed to their first language (L1). The present study investigates the extent to which linguistic experience affects the ability of L2 listeners to benefit from a delay between the onset of a masker and the onset of a word. In a previous study (Ben-David, Tse & Schneider, 2012), word recognition thresholds for young L1s were found to improve with the increase in the delay between the onset of a masker (either a stationary noise or a babble of voices) and the onset of a word. The investigators interpreted this result as reflecting the ability of L1 listeners to rapidly segregate the target words from a masker. Given stream segregation depends, in part, on top-down knowledge-driven processes, we might expect stream segregation to be more “sluggish” for L2 listeners than for L1 listeners, especially when the masker consists of a babble of L2 voices. In the present study, we compared the ability of native English speakers to those who had either recent or long-term immersion in English as L2, to benefit from a delay between masker onset and word onset for English words. Results show that thresholds were higher for the two L2s groups than for the L1s. However, the rate at which word recognition improved with word-onset delay was unaffected by linguistic status, both when words were presented in noise, and in babble. Hence, for young listeners, stream segregation appears to be independent of linguistic status, suggesting that bottom-up sensory mechanisms play a large role in stream segregation in this paradigm. The implications of a failure of older L1 listeners (in Ben-David et al.) to benefit from a word-onset delay when the masker is a babble of voices are discussed.



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Frequency discrimination in the common marmoset (Callithrix jacchus)

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Michael S. Osmanski, Xindong Song, Yueqi Guo, Xiaoqin Wang
The common marmoset (Callithrix jacchus) is a highly vocal New World primate species that has emerged in recent years as a promising model system for studies of auditory and vocal processing. Our recent studies have examined perceptual mechanisms related to the pitch of harmonic complex tones in this species. However, no previous psychoacoustic work has measured marmosets’ frequency discrimination abilities for pure tones across a broad frequency range. Here we systematically examined frequency difference limens (FDLs), which measure the minimum discriminable frequency difference between two pure tones, in marmosets across most of their hearing range. Results show that marmosets’ FDLs are comparable to other New World primates, with lowest values in the frequency range of ∼3.5–14 kHz. This region of lowest FDLs corresponds with the region of lowest hearing thresholds in this species measured in our previous study and also with the greatest concentration of spectral energy in the major types of marmoset vocalizations. These data suggest that frequency discrimination in the common marmoset may have evolved to match the hearing sensitivity and spectral characteristics of this species’ vocalizations.



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Controlled Exploration of the Effects of Conductive Hearing Loss on Wideband Acoustic Immittance in Human Cadaveric Preparations

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Gabrielle R. Merchant, Saumil N. Merchant, John J. Rosowski, Hideko Heidi Nakajima
Current clinical practice cannot distinguish, with any degree of certainty, the multiple pathologies that produce conductive hearing loss in patients with an intact tympanic membrane and a well-aerated middle ear without exploratory surgery. The lack of an effective non-surgical diagnostic procedure leads to unnecessary surgery and limits the accuracy of information available during pre-surgical consultations with the patient. A non-invasive measurement to determine the pathology responsible for a conductive hearing loss prior to surgery would be of great value. This work investigates the utility of wideband acoustic immittance (WAI), a non-invasive measure of middle-ear mobility, in the differential diagnosis of pathologies responsible for conductive hearing loss.We focus on determining whether power reflectance (PR), a derivative of WAI, is a possible solution to this problem. PR is a measure of the fraction of sound power reflected from the middle ear when a sound stimulus is presented to the ear canal. PR and other metrics of middle-ear performance (such as ossicular motion via laser Doppler vibrometry) were measured in well-controlled human temporal bone preparations with simulated pathologies. We report measurements before and after simulation of stapes fixation (n=8), malleus fixation (n=10), ossicular disarticulation (n=10), and superior canal dehiscence (n=8). Our results are consistent with the small set of previously published reflectance measurements made in temporal bones and patients. In this present study, these temporal bone experiments with different middle- and inner-ear pathologies were compared to the initial normal state by analyzing both WAI and ossicular motion, demonstrating that WAI can be a valuable tool in the diagnosis of conductive hearing loss.



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Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): N.P.M. Todd, S. Govender, J.G. Colebatch
Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.



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Drug discovery for hearing loss: Phenotypic screening of chemical compounds on primary cultures of the spiral ganglion

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Donna S. Whitlon
In the United States there are, at present, no drugs that are specifically FDA approved to treat hearing loss. Although several clinical trials are ongoing, including one testing D-methionine that is supported by the US Army, none of these trials directly address the effect of noise exposure on cochlear spiral ganglion neurons. We recently published the first report of a systematic chemical compound screen using primary, mammalian spiral ganglion cultures in which we were able to detect a compound and others in its class that increased neurite elongation, a critical step in restoring cochlear synapses after noise induced hearing loss. Here we discuss the issues, both pro and con, that influenced the development of our approach. These considerations may be useful for future compound screens that target the same or other attributes of cochlear spiral ganglion neurons.



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via IFTTT

Does the degree of linguistic experience (native versus nonnative) modulate the degree to which listeners can benefit from a delay between the onset of the maskers and the onset of the target speech?

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Boaz M. Ben-David, Meital Avivi-Reich, Bruce A. Schneider
Background noise has a greater adverse effect on word recognition when people are listening in their second language (L2) as opposed to their first language (L1). The present study investigates the extent to which linguistic experience affects the ability of L2 listeners to benefit from a delay between the onset of a masker and the onset of a word. In a previous study (Ben-David, Tse & Schneider, 2012), word recognition thresholds for young L1s were found to improve with the increase in the delay between the onset of a masker (either a stationary noise or a babble of voices) and the onset of a word. The investigators interpreted this result as reflecting the ability of L1 listeners to rapidly segregate the target words from a masker. Given stream segregation depends, in part, on top-down knowledge-driven processes, we might expect stream segregation to be more “sluggish” for L2 listeners than for L1 listeners, especially when the masker consists of a babble of L2 voices. In the present study, we compared the ability of native English speakers to those who had either recent or long-term immersion in English as L2, to benefit from a delay between masker onset and word onset for English words. Results show that thresholds were higher for the two L2s groups than for the L1s. However, the rate at which word recognition improved with word-onset delay was unaffected by linguistic status, both when words were presented in noise, and in babble. Hence, for young listeners, stream segregation appears to be independent of linguistic status, suggesting that bottom-up sensory mechanisms play a large role in stream segregation in this paradigm. The implications of a failure of older L1 listeners (in Ben-David et al.) to benefit from a word-onset delay when the masker is a babble of voices are discussed.



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Frequency discrimination in the common marmoset (Callithrix jacchus)

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Michael S. Osmanski, Xindong Song, Yueqi Guo, Xiaoqin Wang
The common marmoset (Callithrix jacchus) is a highly vocal New World primate species that has emerged in recent years as a promising model system for studies of auditory and vocal processing. Our recent studies have examined perceptual mechanisms related to the pitch of harmonic complex tones in this species. However, no previous psychoacoustic work has measured marmosets’ frequency discrimination abilities for pure tones across a broad frequency range. Here we systematically examined frequency difference limens (FDLs), which measure the minimum discriminable frequency difference between two pure tones, in marmosets across most of their hearing range. Results show that marmosets’ FDLs are comparable to other New World primates, with lowest values in the frequency range of ∼3.5–14 kHz. This region of lowest FDLs corresponds with the region of lowest hearing thresholds in this species measured in our previous study and also with the greatest concentration of spectral energy in the major types of marmoset vocalizations. These data suggest that frequency discrimination in the common marmoset may have evolved to match the hearing sensitivity and spectral characteristics of this species’ vocalizations.



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via IFTTT

Controlled Exploration of the Effects of Conductive Hearing Loss on Wideband Acoustic Immittance in Human Cadaveric Preparations

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Gabrielle R. Merchant, Saumil N. Merchant, John J. Rosowski, Hideko Heidi Nakajima
Current clinical practice cannot distinguish, with any degree of certainty, the multiple pathologies that produce conductive hearing loss in patients with an intact tympanic membrane and a well-aerated middle ear without exploratory surgery. The lack of an effective non-surgical diagnostic procedure leads to unnecessary surgery and limits the accuracy of information available during pre-surgical consultations with the patient. A non-invasive measurement to determine the pathology responsible for a conductive hearing loss prior to surgery would be of great value. This work investigates the utility of wideband acoustic immittance (WAI), a non-invasive measure of middle-ear mobility, in the differential diagnosis of pathologies responsible for conductive hearing loss.We focus on determining whether power reflectance (PR), a derivative of WAI, is a possible solution to this problem. PR is a measure of the fraction of sound power reflected from the middle ear when a sound stimulus is presented to the ear canal. PR and other metrics of middle-ear performance (such as ossicular motion via laser Doppler vibrometry) were measured in well-controlled human temporal bone preparations with simulated pathologies. We report measurements before and after simulation of stapes fixation (n=8), malleus fixation (n=10), ossicular disarticulation (n=10), and superior canal dehiscence (n=8). Our results are consistent with the small set of previously published reflectance measurements made in temporal bones and patients. In this present study, these temporal bone experiments with different middle- and inner-ear pathologies were compared to the initial normal state by analyzing both WAI and ossicular motion, demonstrating that WAI can be a valuable tool in the diagnosis of conductive hearing loss.



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Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): N.P.M. Todd, S. Govender, J.G. Colebatch
Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.



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via IFTTT

Drug discovery for hearing loss: Phenotypic screening of chemical compounds on primary cultures of the spiral ganglion

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Donna S. Whitlon
In the United States there are, at present, no drugs that are specifically FDA approved to treat hearing loss. Although several clinical trials are ongoing, including one testing D-methionine that is supported by the US Army, none of these trials directly address the effect of noise exposure on cochlear spiral ganglion neurons. We recently published the first report of a systematic chemical compound screen using primary, mammalian spiral ganglion cultures in which we were able to detect a compound and others in its class that increased neurite elongation, a critical step in restoring cochlear synapses after noise induced hearing loss. Here we discuss the issues, both pro and con, that influenced the development of our approach. These considerations may be useful for future compound screens that target the same or other attributes of cochlear spiral ganglion neurons.



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via IFTTT

Does the degree of linguistic experience (native versus nonnative) modulate the degree to which listeners can benefit from a delay between the onset of the maskers and the onset of the target speech?

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Boaz M. Ben-David, Meital Avivi-Reich, Bruce A. Schneider
Background noise has a greater adverse effect on word recognition when people are listening in their second language (L2) as opposed to their first language (L1). The present study investigates the extent to which linguistic experience affects the ability of L2 listeners to benefit from a delay between the onset of a masker and the onset of a word. In a previous study (Ben-David, Tse & Schneider, 2012), word recognition thresholds for young L1s were found to improve with the increase in the delay between the onset of a masker (either a stationary noise or a babble of voices) and the onset of a word. The investigators interpreted this result as reflecting the ability of L1 listeners to rapidly segregate the target words from a masker. Given stream segregation depends, in part, on top-down knowledge-driven processes, we might expect stream segregation to be more “sluggish” for L2 listeners than for L1 listeners, especially when the masker consists of a babble of L2 voices. In the present study, we compared the ability of native English speakers to those who had either recent or long-term immersion in English as L2, to benefit from a delay between masker onset and word onset for English words. Results show that thresholds were higher for the two L2s groups than for the L1s. However, the rate at which word recognition improved with word-onset delay was unaffected by linguistic status, both when words were presented in noise, and in babble. Hence, for young listeners, stream segregation appears to be independent of linguistic status, suggesting that bottom-up sensory mechanisms play a large role in stream segregation in this paradigm. The implications of a failure of older L1 listeners (in Ben-David et al.) to benefit from a word-onset delay when the masker is a babble of voices are discussed.



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Frequency discrimination in the common marmoset (Callithrix jacchus)

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Michael S. Osmanski, Xindong Song, Yueqi Guo, Xiaoqin Wang
The common marmoset (Callithrix jacchus) is a highly vocal New World primate species that has emerged in recent years as a promising model system for studies of auditory and vocal processing. Our recent studies have examined perceptual mechanisms related to the pitch of harmonic complex tones in this species. However, no previous psychoacoustic work has measured marmosets’ frequency discrimination abilities for pure tones across a broad frequency range. Here we systematically examined frequency difference limens (FDLs), which measure the minimum discriminable frequency difference between two pure tones, in marmosets across most of their hearing range. Results show that marmosets’ FDLs are comparable to other New World primates, with lowest values in the frequency range of ∼3.5–14 kHz. This region of lowest FDLs corresponds with the region of lowest hearing thresholds in this species measured in our previous study and also with the greatest concentration of spectral energy in the major types of marmoset vocalizations. These data suggest that frequency discrimination in the common marmoset may have evolved to match the hearing sensitivity and spectral characteristics of this species’ vocalizations.



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via IFTTT

Controlled Exploration of the Effects of Conductive Hearing Loss on Wideband Acoustic Immittance in Human Cadaveric Preparations

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): Gabrielle R. Merchant, Saumil N. Merchant, John J. Rosowski, Hideko Heidi Nakajima
Current clinical practice cannot distinguish, with any degree of certainty, the multiple pathologies that produce conductive hearing loss in patients with an intact tympanic membrane and a well-aerated middle ear without exploratory surgery. The lack of an effective non-surgical diagnostic procedure leads to unnecessary surgery and limits the accuracy of information available during pre-surgical consultations with the patient. A non-invasive measurement to determine the pathology responsible for a conductive hearing loss prior to surgery would be of great value. This work investigates the utility of wideband acoustic immittance (WAI), a non-invasive measure of middle-ear mobility, in the differential diagnosis of pathologies responsible for conductive hearing loss.We focus on determining whether power reflectance (PR), a derivative of WAI, is a possible solution to this problem. PR is a measure of the fraction of sound power reflected from the middle ear when a sound stimulus is presented to the ear canal. PR and other metrics of middle-ear performance (such as ossicular motion via laser Doppler vibrometry) were measured in well-controlled human temporal bone preparations with simulated pathologies. We report measurements before and after simulation of stapes fixation (n=8), malleus fixation (n=10), ossicular disarticulation (n=10), and superior canal dehiscence (n=8). Our results are consistent with the small set of previously published reflectance measurements made in temporal bones and patients. In this present study, these temporal bone experiments with different middle- and inner-ear pathologies were compared to the initial normal state by analyzing both WAI and ossicular motion, demonstrating that WAI can be a valuable tool in the diagnosis of conductive hearing loss.



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Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin

Publication date: Available online 3 August 2016
Source:Hearing Research
Author(s): N.P.M. Todd, S. Govender, J.G. Colebatch
Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.



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Drug discovery for hearing loss: Phenotypic screening of chemical compounds on primary cultures of the spiral ganglion

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Donna S. Whitlon
In the United States there are, at present, no drugs that are specifically FDA approved to treat hearing loss. Although several clinical trials are ongoing, including one testing D-methionine that is supported by the US Army, none of these trials directly address the effect of noise exposure on cochlear spiral ganglion neurons. We recently published the first report of a systematic chemical compound screen using primary, mammalian spiral ganglion cultures in which we were able to detect a compound and others in its class that increased neurite elongation, a critical step in restoring cochlear synapses after noise induced hearing loss. Here we discuss the issues, both pro and con, that influenced the development of our approach. These considerations may be useful for future compound screens that target the same or other attributes of cochlear spiral ganglion neurons.



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Does the degree of linguistic experience (native versus nonnative) modulate the degree to which listeners can benefit from a delay between the onset of the maskers and the onset of the target speech?

Publication date: Available online 2 August 2016
Source:Hearing Research
Author(s): Boaz M. Ben-David, Meital Avivi-Reich, Bruce A. Schneider
Background noise has a greater adverse effect on word recognition when people are listening in their second language (L2) as opposed to their first language (L1). The present study investigates the extent to which linguistic experience affects the ability of L2 listeners to benefit from a delay between the onset of a masker and the onset of a word. In a previous study (Ben-David, Tse & Schneider, 2012), word recognition thresholds for young L1s were found to improve with the increase in the delay between the onset of a masker (either a stationary noise or a babble of voices) and the onset of a word. The investigators interpreted this result as reflecting the ability of L1 listeners to rapidly segregate the target words from a masker. Given stream segregation depends, in part, on top-down knowledge-driven processes, we might expect stream segregation to be more “sluggish” for L2 listeners than for L1 listeners, especially when the masker consists of a babble of L2 voices. In the present study, we compared the ability of native English speakers to those who had either recent or long-term immersion in English as L2, to benefit from a delay between masker onset and word onset for English words. Results show that thresholds were higher for the two L2s groups than for the L1s. However, the rate at which word recognition improved with word-onset delay was unaffected by linguistic status, both when words were presented in noise, and in babble. Hence, for young listeners, stream segregation appears to be independent of linguistic status, suggesting that bottom-up sensory mechanisms play a large role in stream segregation in this paradigm. The implications of a failure of older L1 listeners (in Ben-David et al.) to benefit from a word-onset delay when the masker is a babble of voices are discussed.



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