Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and... more Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and treated using standard audiological procedures. Yet, hearing can be much poorer (or more impaired) than audibility predicts because of deficits in the suprathreshold mechanisms that encode the rapidly changing, spectral, temporal, and binaural aspects of the sound. The ability to evaluate these mechanisms requires well-defined stimuli and strict adherence to rigorous psychometric principles. This project reports on the comparison between a laboratory-based and a mobile system’s results for psychoacoustic assessment in adult listeners with normal hearing. A description of both systems employed is provided. Psychoacoustic tests include frequency discrimination, amplitude modulation detection, binaural encoding, and temporal gap detection. Results reported by the mobile system were not significantly different from those collected with the laboratory-based system for most of the tests and w...
Computer Methods and Programs in Biomedicine, 2021
INTRODUCTION Auditory brainstem responses (ABRs) offer a unique opportunity to assess the neural ... more INTRODUCTION Auditory brainstem responses (ABRs) offer a unique opportunity to assess the neural integrity of the peripheral auditory nervous system in individuals presenting with listening difficulties. ABRs are typically recorded and analyzed by an audiologist who manually measures the timing and quality of the waveforms. The interpretation of ABRs requires considerable experience and training, and inappropriate interpretation can lead to incorrect judgments about the integrity of the system. Machine learning (ML) techniques may be a suitable approach to automate ABR interpretation and reduce human error. OBJECTIVES The main objective of this paper was to identify a suitable ML technique to automate the analysis of ABR responses recorded as a part of the electrophysiological testing in the Auditory Processing Disorder clinical test battery. METHODS ABR responses recorded during routine clinical assessment from 136 children being evaluated for auditory processing difficulties were analyzed using several common ML algorithms: Support Vector Machines (SVM), Random Forests (RF), Decision Trees (DT), Gradient Boosting (GB), Extreme Gradient Boosting (Xgboost), and Neural Networks (NN). A variety of signal feature extraction techniques were used to extract features from the ABR waveforms as inputs to the ML algorithms. Statistical significance testing and confusion matrices were used to identify the most robust model capable of accurately identifying neurological abnormalities present in ABRs. RESULTS Clinically significant features in the time-frequency representation of the signal were identified. The ML model trained using the Xgboost algorithm was identified as the most robust model with an accuracy of 92% compared to other models. CONCLUSION The findings of the present study demonstrate that it is possible to develop accurate ML models to automate the process of analyzing ABR waveforms recorded at suprathreshold levels. There is currently no ML-based application to screen children with listening difficulties. Therefore, it is expected that this work will be translated into an evaluation tool that can be used by audiologists in the clinic. Furthermore, this work may aid future researchers in exploring ML paradigms to improve clinical test batteries used by audiologists in achieving accurate diagnoses.
In a series of experiments, multidimensional scaling was used to evaluate the encoding of complex... more In a series of experiments, multidimensional scaling was used to evaluate the encoding of complex sounds by school-aged children (6-11 years) and adults. Listeners rated the similarity of all possible pairs of sounds within a given set. The ratings were used to derive a multidimensional space in which the stimuli were represented as points and the axes represent the perceptual dimensions used in making the judgements. Using a computer procedure listeners heard pairs of sounds and were asked to place two computer images at a distance from one another that reflected their perceived similarity. Experiment I. Age effects. The stimuli were 17, 430 ms signals including 3 pure tones (250, 1000, and 4000 Hz), 6 harmonic complexes consisting of the low (2-6), high (12-16) or wide (2-16) harmonics of either a 110 or 200 Hz fundamental, 2 AM noises (500 Hz and 2000 Hz noises, 12 dB modulation at 6 Hz), 2 FM tones (500 and 2000 Hz, frequency modulated at 10 Hz), 3 narrow band noises (centred at...
Objective: To assess the performance of an active transcutaneous implantable-bone conduction devi... more Objective: To assess the performance of an active transcutaneous implantable-bone conduction device (TI-BCD), and to evaluate the benefit of device digital signal processing (DSP) features in challenging listening environments. Design: Participants were tested at 1-and 3-month post-activation of the TI-BCD. At each session, aided and unaided phoneme perception was assessed using the Ling-6 test. Speech reception thresholds (SRTs) and quality ratings of speech and music samples were collected in noisy and reverberant environments, with and without the DSP features. Self-assessment of the device performance was obtained using the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. Study sample: Six adults with conductive or mixed hearing loss. Results: Average SRTs were 2.9 and 12.3 dB in low and high reverberation environments, respectively, which improved to À1.7 and 8.7 dB, respectively with the DSP features. In addition, speech quality ratings improved by 23 points with the DSP features when averaged across all environmental conditions. Improvement scores on APHAB scales revealed a statistically significant aided benefit. Conclusions: Noise and reverberation significantly impacted speech recognition performance and perceived sound quality. DSP features (directional microphone processing and adaptive noise reduction) significantly enhanced subjects' performance in these challenging listening environments.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2019
This paper evaluated the performance of an envelope enhancement (EE) algorithm subjectively by ch... more This paper evaluated the performance of an envelope enhancement (EE) algorithm subjectively by children with auditory processing disorder (APD), and objectively through computational models. Speech intelligibility data was collected from children with APD, for unprocessed and envelope-enhanced speech in the presence of stationary and non-stationary background noise at different signal to noise ratios (SNRs), both with and without noise reduction (NR) algorithms as a front-end to the EE algorithm. Furthermore, intrusive and non-intrusive objective speech intelligibility metrics were derived to predict the perceptual impact of this EE algorithm. Subjective data for stationary noise conditions revealed that the combination of NR and EE algorithms significantly improved the speech intelligibility scores at poor SNRs. In contrast, the same combination was ineffective in improving speech intelligibility in non-stationary noise conditions. Taken together, subjective results suggest that exaggerating the envelope cues improves speech identification scores for children with APD. However, the benefit obtained varies depending upon the type and level of the background noise. Both intrusive and non-intrusive objective speech intelligibility estimators exhibited good correlation with the subjective data, with the intrusive metric demonstrating better generalization capabilities. Implications of these results for hearing aid applications for children with APD is discussed.
The medial olivocochlear reflex (MOCR) has been implicated in several auditory processes. The put... more The medial olivocochlear reflex (MOCR) has been implicated in several auditory processes. The putative role of the MOCR in improving speech perception in noise is particularly relevant for children who complain of listening difficulties (LiD). The hypothesis that the MOCR may be impaired in individuals with LiD or auditory processing disorder has led to several investigations but without consensus. In two related studies, we compared the MOCR functioning of children with LiD and typically developing (TD) children in the same age range (7–17 years). In Study 1, we investigated ipsilateral, contralateral, and bilateral MOCR using forward-masked click-evoked otoacoustic emissions (CEOAEs; n = 17 TD, 17 LiD). In Study 2, we employed three OAE types: CEOAEs ( n = 16 TD, 21 LiD), stimulus frequency OAEs ( n = 21 TD, 30 LiD), and distortion product OAEs ( n = 17 TD, 22 LiD) in a contralateral noise paradigm. Results from both studies suggest that the MOCR functioning is not significantly d...
Speech perception in a noisy environment is a significant challenge for individuals with auditory... more Speech perception in a noisy environment is a significant challenge for individuals with auditory processing deficits. Evidence exists that exaggerating the slow temporal modulations may enhance speech perception for these individuals in the absence or presence of background noise. Nevertheless, a comprehensive assessment of envelope enhancement algorithms is lacking. In the present research study, two different schemes of envelope enhancement (dynamic and static) were evaluated subjectively and objectively for different types and levels of background noise with and without applying a noise reduction algorithm. In the subjective assessment, the dynamic envelope enhancement algorithm was evaluated with three different subjective groups including, twelve normal adults, twelve normal children, and eleven children with suspected auditory processing disorder (APD). The subjective results revealed that the speech intelligibility scores were lower for APD subjects compared to both normal adults and normal children. The subjective results also demonstrated that enhancing the temporal envelope is much more beneficial for subjects with suspected APD when compared to normal adults and children participating in the subjective experiment. In the objective assessment, the Hearing Aid Speech Perception Index (HASPI) was employed to predict the speech intelligibility scores which correlated highly with the subjective data. Comprehensive objective experiments demonstrated that both dynamic and static envelope enhancement algorithms are only effective in improving speech perception under certain processing conditions that depended on the type, level and location of the background noise. It is also shown that the application of a noise reduction algorithm prior to the envelope enhancement algorithms will increase their range of effectiveness.
A Sound Foundation Through Early Amplification, 2007
It is always difficult to describe what we mean when we discuss auditory processing disorders. Th... more It is always difficult to describe what we mean when we discuss auditory processing disorders. There are many different interpretations of what such a disorder looks like, what tests should be used to diagnose it, where the difficulties lie anatomically or ...
The Journal of the Acoustical Society of America, 1999
This paper considers an acoustic basis for speech intelligibility and evaluates various acoustica... more This paper considers an acoustic basis for speech intelligibility and evaluates various acoustically based speech intelligibility prediction algorithms. Earlier research indicates that speech intelligibility does not require preservation of spectral and temporal fine‐structure, but is highly dependent on the preservation of the amplitude component of the modulation spectrum [R. Drullman, J. Acoust. Soc. Am. 97, 585–592 (1995)]. This study assessed the importance of the phase component of the modulation spectrum using a 21‐alternative forced‐choice consonant perception test. Temporal and spectral fine‐structure were removed by modulating a white noise carrier with 50 Hz low‐pass filtered speech amplitude envelopes in 4, 8, or 24 discrete bands. Modulation spectrum phase was distorted by imposing a random delay in each discrete band. Behavioral results are discussed in light of intelligibility predictions generated by the articulation index [N. R. French and J. C. Steinberg, J. Acoust. Soc. Am. 19, 90–119 (...
Behavioral manifestations of processing deficits associated with auditory processing disor-der (A... more Behavioral manifestations of processing deficits associated with auditory processing disor-der (APD) have been well documented. However, little is known about their anatomical underpinnings, especially cochlear processing. Cochlear delays, a proxy for cochlear tun-ing, measured using stimulus frequency otoacoustic emission (SFOAE) group delay, and the influence of the medial olivocochlear (MOC) system activation at the auditory periphery was studied in 23 children suspected with APD (sAPD) and 22 typically developing (TD) children. Results suggest that children suspected with APD have longer SFOAE group delays (possibly due to sharper cochlear tuning) and reduced MOC function compared to TD children. Other differences between the groups include correlation between MOC func-tion and SFOAE delay in quiet in the TD group, and lack thereof in the sAPD group. MOC-mediated changes in SFOAE delay were in opposite directions between groups: increase in delay in TD vs. reduction in delay in ...
Purpose A growing body of evidence indicates that treatment of hearing loss by provision of heari... more Purpose A growing body of evidence indicates that treatment of hearing loss by provision of hearing aids leads to improvements in auditory and visual working memory. The purpose of this study was to assess whether similar working memory benefits are observed following provision of cochlear implants (CIs). Method Fifteen adults with postlingually acquired severe bilateral sensorineural hearing loss completed the prospective longitudinal study. Participants were candidates for bilateral cochlear implantation with some aidable hearing in each ear. Implantation surgeries were carried out sequentially, approximately 1 year apart. Working memory was measured with the visual Reading Span Test (Daneman & Carpenter, 1980) at 5 time points: pre-operatively following a 6-month bilateral hearing aid trial, after 6 and 12 months of bimodal (CI plus contralateral hearing aid) listening experience following the 1st CI surgery and activation, and again after 6 and 12 months of bilateral CI listenin...
The test battery typically used for the diagnosis of auditory processing disorder (APD) is highly... more The test battery typically used for the diagnosis of auditory processing disorder (APD) is highly heterogeneous, with an emphasis on the central auditory nervous system. As such, the peripheral auditory system is typically only screened for the presence of an overt hearing loss. Our previous work suggested that children suspected of APD (sAPD) have atypically sharp cochlear tuning when measured using stimulus frequency otoacoustic emission (SFOAE) group delay. In the present work, we extend our previous findings and test the hypothesis that cochlear tuning influences auditory brainstem response (ABR) latencies. Our hypothesis is based on filter theory, which suggests that a sharper filter will take longer to build-up and ring longer. We predicted that sharper cochlear filters in sAPD should result in delayed ABR wave latencies and will be associated with poorer performance on speech perception tests. Preliminary data from 16 sAPD and 6 typically developing children show a positive correlation between coch...
Background: The ASHA recommends including electrophysiological measures in an auditory processing... more Background: The ASHA recommends including electrophysiological measures in an auditory processing disorder (APD) assessment battery, but few audiologists do so, potentially because of limited published evidence for its utility. Purpose: This study compared the auditory brainstem responses (ABRs) of children with APD with agematched children and adults. Study Sample: This study retrospectively examined the records of 108 children suspected of APD (sAPD) who had click-evoked ABRs recorded as part of their clinical assessment. Twenty adults and 22 typically developing (TD) children were recruited as controls. Data collection and Analysis: Click-evoked ABRs were recorded at slow (13.3 clicks/sec) and faster (57.7 clicks/sec) stimulation rates. ABRs were analyzed using typical clinical measures (latencies and interpeak intervals for waves I, III, and V) and using a model proposed by Ponton et al that offered a more detailed analysis of axonal conduction time and synaptic transmission delay. Results: Both clinical measures and the Ponton model analysis showed no significant differences between TD children and adults. Children sAPD showed absolute latencies that were significantly prolonged when compared with adults but not when compared with TD children. But individual children sAPD showed clinically significant delays (.2 standard deviations of TD children's data). Examination of responses delineating axonal versus synaptic transmission showed significant delays in synaptic transmission in the group of children sAPD in comparison to TD children and adults. These results suggest that a significant portion of children with listening difficulties showed evidence of reduced or atypical brainstem functioning. Examining the responses for axonal and synaptic delays revealed evidence of a synaptic pattern of abnormalities in a significant portion (37.03%) of children sAPD. Such observations could provide objective evidence of factors potentially contributing to listening difficulties that are frequently reported in children identified with APD. Conclusions: Children sAPD often showed abnormalities in the ABR, suggesting a neurophysiologic origin of their reported difficulties, frequently originating at or before the first synapse. This study provides supportive evidence for the value of click-evoked ABRs in comprehensive auditory processing assessment batteries.
Abstract Objective: The purpose of this study was to examine developmental trends in spectral rip... more Abstract Objective: The purpose of this study was to examine developmental trends in spectral ripple discrimination (SRD) and to compare the performance of typically developing children to children with auditory processing disorder (APD). Study design: Cross-sectional study. Study sample: Fifteen children with APD, as well as 17 typically developing children and 14 adults reporting no listening or academic difficulties participated. Results: Typically developing children showed poor SRD thresholds compared to adults, indicating prolonged maturation of spectral shape recognition. Both typically developing children and APD children showed a maturational trend in SRD, but a General Linear Model fit to their thresholds showed that children with APD displayed SRD thresholds that were significantly poorer than those of typically developing children when controlling for age. This suggests that in APD children, SRD maturation lags behind typically developing children. Conclusion: Poor spectral ripple discrimination may explain some of the listening difficulties experienced by children with APD.
OBJECTIVES We sought to investigate whether children referred to our audiology clinic with a comp... more OBJECTIVES We sought to investigate whether children referred to our audiology clinic with a complaint of listening difficulty, that is, suspected of auditory processing disorder (APD), have difficulties localizing sounds in noise and whether they have reduced benefit from spatial release from masking. DESIGN Forty-seven typically hearing children in the age range of 7 to 17 years took part in the study. Twenty-one typically developing (TD) children served as controls, and the other 26 children, referred to our audiology clinic with listening problems, were the study group: suspected APD (sAPD). The ability to localize a speech target (the word "baseball") was measured in quiet, broadband noise, and speech-babble in a hemi-anechoic chamber. Participants stood at the center of a loudspeaker array that delivered the target in a diffused noise-field created by presenting independent noise from four loudspeakers spaced 90° apart starting at 45°. In the noise conditions, the signal-to-noise ratio was varied between -12 and 0 dB in 6-dB steps by keeping the noise level constant at 66 dB SPL and varying the target level. Localization ability was indexed by two metrics, one assessing variability in lateral plane [lateral scatter (Lscat)] and the other accuracy in the front/back dimension [front/back percent correct (FBpc)]. Spatial release from masking (SRM) was measured using a modified version of the Hearing in Noise Test (HINT). In this HINT paradigm, speech targets were always presented from the loudspeaker at 0°, and a single noise source was presented either at 0°, 90°, or 270° at 65 dB A. The SRM was calculated as the difference between the 50% correct HINT speech reception threshold obtained when both speech and noise were collocated at 0° and when the noise was presented at either 90° or 270°. RESULTS As expected, in both groups, localization in noise improved as a function of signal-to-noise ratio. Broadband noise caused significantly larger disruption in FBpc than in Lscat when compared with speech babble. There were, however, no group effects or group interactions, suggesting that the children in the sAPD group did not differ significantly from TD children in either localization metric (Lscat and FBpc). While a significant SRM was observed in both groups, there were no group effects or group interactions. Collectively, the data suggest that children in the sAPD group did not differ significantly from the TD group for either binaural measure investigated in the study. CONCLUSIONS As is evident from a few poor performers, some children with listening difficulties may have difficulty in localizing sounds and may not benefit from spatial separation of speech and noise. However, the heterogeneity in APD and the variability in our data do not support the notion that localization is a global APD problem. Future studies that employ a case study design might provide more insights.
Dynamics of spontaneous alpha activity correlate with language ability in young children" (2019).... more Dynamics of spontaneous alpha activity correlate with language ability in young children" (2019). Communication Sciences and Disorders Publications. 17.
Journal of the American Academy of Audiology, 2017
Previous studies have suggested elevated reflex thresholds in children with auditory processing d... more Previous studies have suggested elevated reflex thresholds in children with auditory processing disorders (APDs). However, some aspects of the child's ear such as ear canal volume and static compliance of the middle ear could possibly affect the measurements of reflex thresholds and thus impact its interpretation. Sound levels used to elicit reflexes in a child's ear may be higher than predicted by calibration in a standard 2-cc coupler, and lower static compliance could make visualization of very small changes in impedance at threshold difficult. For this purpose, it is important to evaluate threshold data with consideration of differences between children and adults. A set of studies were conducted. The first compared reflex thresholds obtained using standard clinical procedures in children with suspected APD to that of typically developing children and adults to test the replicability of previous studies. The second study examined the impact of ear canal volume on estimat...
The Journal of the Acoustical Society of America, 2016
Children as young as 5 yr old localize sounds as accurately as adults in quiet in the frontal hem... more Children as young as 5 yr old localize sounds as accurately as adults in quiet in the frontal hemifield. However, children's ability to localize in noise and in the front/back (F/B) dimension are scantily studied. To address this, the first part of this study investigated localization-in-noise ability of children vs young adults in two maskers: broadband noise (BBN) and speech-babble (SB) at three signal-to-noise ratios: -12, -6, and 0 dB. In the second part, relationship between binaural medial olivocochlear system (MOC) function and localization-in-noise was investigated. In both studies, 21 children and 21 young adults participated. Results indicate, while children are able to differentiate sounds arriving in the F/B dimension on par with adults in quiet and in BBN, larger differences were found for SB. Accuracy of children's localization in noise (for both maskers) in the lateral plane was also poorer than adults'. Significant differences in binaural MOC interaction (mBIC; the difference between the sum of two monaural- and binaural-MOC strength) between adults and children were also found. For reasons which are not clear, adult F/B localization in BBN correlates better with mBIC while children's F/B localization in SB correlated better with binaural MOC strength.
Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and... more Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and treated using standard audiological procedures. Yet, hearing can be much poorer (or more impaired) than audibility predicts because of deficits in the suprathreshold mechanisms that encode the rapidly changing, spectral, temporal, and binaural aspects of the sound. The ability to evaluate these mechanisms requires well-defined stimuli and strict adherence to rigorous psychometric principles. This project reports on the comparison between a laboratory-based and a mobile system’s results for psychoacoustic assessment in adult listeners with normal hearing. A description of both systems employed is provided. Psychoacoustic tests include frequency discrimination, amplitude modulation detection, binaural encoding, and temporal gap detection. Results reported by the mobile system were not significantly different from those collected with the laboratory-based system for most of the tests and w...
Computer Methods and Programs in Biomedicine, 2021
INTRODUCTION Auditory brainstem responses (ABRs) offer a unique opportunity to assess the neural ... more INTRODUCTION Auditory brainstem responses (ABRs) offer a unique opportunity to assess the neural integrity of the peripheral auditory nervous system in individuals presenting with listening difficulties. ABRs are typically recorded and analyzed by an audiologist who manually measures the timing and quality of the waveforms. The interpretation of ABRs requires considerable experience and training, and inappropriate interpretation can lead to incorrect judgments about the integrity of the system. Machine learning (ML) techniques may be a suitable approach to automate ABR interpretation and reduce human error. OBJECTIVES The main objective of this paper was to identify a suitable ML technique to automate the analysis of ABR responses recorded as a part of the electrophysiological testing in the Auditory Processing Disorder clinical test battery. METHODS ABR responses recorded during routine clinical assessment from 136 children being evaluated for auditory processing difficulties were analyzed using several common ML algorithms: Support Vector Machines (SVM), Random Forests (RF), Decision Trees (DT), Gradient Boosting (GB), Extreme Gradient Boosting (Xgboost), and Neural Networks (NN). A variety of signal feature extraction techniques were used to extract features from the ABR waveforms as inputs to the ML algorithms. Statistical significance testing and confusion matrices were used to identify the most robust model capable of accurately identifying neurological abnormalities present in ABRs. RESULTS Clinically significant features in the time-frequency representation of the signal were identified. The ML model trained using the Xgboost algorithm was identified as the most robust model with an accuracy of 92% compared to other models. CONCLUSION The findings of the present study demonstrate that it is possible to develop accurate ML models to automate the process of analyzing ABR waveforms recorded at suprathreshold levels. There is currently no ML-based application to screen children with listening difficulties. Therefore, it is expected that this work will be translated into an evaluation tool that can be used by audiologists in the clinic. Furthermore, this work may aid future researchers in exploring ML paradigms to improve clinical test batteries used by audiologists in achieving accurate diagnoses.
In a series of experiments, multidimensional scaling was used to evaluate the encoding of complex... more In a series of experiments, multidimensional scaling was used to evaluate the encoding of complex sounds by school-aged children (6-11 years) and adults. Listeners rated the similarity of all possible pairs of sounds within a given set. The ratings were used to derive a multidimensional space in which the stimuli were represented as points and the axes represent the perceptual dimensions used in making the judgements. Using a computer procedure listeners heard pairs of sounds and were asked to place two computer images at a distance from one another that reflected their perceived similarity. Experiment I. Age effects. The stimuli were 17, 430 ms signals including 3 pure tones (250, 1000, and 4000 Hz), 6 harmonic complexes consisting of the low (2-6), high (12-16) or wide (2-16) harmonics of either a 110 or 200 Hz fundamental, 2 AM noises (500 Hz and 2000 Hz noises, 12 dB modulation at 6 Hz), 2 FM tones (500 and 2000 Hz, frequency modulated at 10 Hz), 3 narrow band noises (centred at...
Objective: To assess the performance of an active transcutaneous implantable-bone conduction devi... more Objective: To assess the performance of an active transcutaneous implantable-bone conduction device (TI-BCD), and to evaluate the benefit of device digital signal processing (DSP) features in challenging listening environments. Design: Participants were tested at 1-and 3-month post-activation of the TI-BCD. At each session, aided and unaided phoneme perception was assessed using the Ling-6 test. Speech reception thresholds (SRTs) and quality ratings of speech and music samples were collected in noisy and reverberant environments, with and without the DSP features. Self-assessment of the device performance was obtained using the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. Study sample: Six adults with conductive or mixed hearing loss. Results: Average SRTs were 2.9 and 12.3 dB in low and high reverberation environments, respectively, which improved to À1.7 and 8.7 dB, respectively with the DSP features. In addition, speech quality ratings improved by 23 points with the DSP features when averaged across all environmental conditions. Improvement scores on APHAB scales revealed a statistically significant aided benefit. Conclusions: Noise and reverberation significantly impacted speech recognition performance and perceived sound quality. DSP features (directional microphone processing and adaptive noise reduction) significantly enhanced subjects' performance in these challenging listening environments.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2019
This paper evaluated the performance of an envelope enhancement (EE) algorithm subjectively by ch... more This paper evaluated the performance of an envelope enhancement (EE) algorithm subjectively by children with auditory processing disorder (APD), and objectively through computational models. Speech intelligibility data was collected from children with APD, for unprocessed and envelope-enhanced speech in the presence of stationary and non-stationary background noise at different signal to noise ratios (SNRs), both with and without noise reduction (NR) algorithms as a front-end to the EE algorithm. Furthermore, intrusive and non-intrusive objective speech intelligibility metrics were derived to predict the perceptual impact of this EE algorithm. Subjective data for stationary noise conditions revealed that the combination of NR and EE algorithms significantly improved the speech intelligibility scores at poor SNRs. In contrast, the same combination was ineffective in improving speech intelligibility in non-stationary noise conditions. Taken together, subjective results suggest that exaggerating the envelope cues improves speech identification scores for children with APD. However, the benefit obtained varies depending upon the type and level of the background noise. Both intrusive and non-intrusive objective speech intelligibility estimators exhibited good correlation with the subjective data, with the intrusive metric demonstrating better generalization capabilities. Implications of these results for hearing aid applications for children with APD is discussed.
The medial olivocochlear reflex (MOCR) has been implicated in several auditory processes. The put... more The medial olivocochlear reflex (MOCR) has been implicated in several auditory processes. The putative role of the MOCR in improving speech perception in noise is particularly relevant for children who complain of listening difficulties (LiD). The hypothesis that the MOCR may be impaired in individuals with LiD or auditory processing disorder has led to several investigations but without consensus. In two related studies, we compared the MOCR functioning of children with LiD and typically developing (TD) children in the same age range (7–17 years). In Study 1, we investigated ipsilateral, contralateral, and bilateral MOCR using forward-masked click-evoked otoacoustic emissions (CEOAEs; n = 17 TD, 17 LiD). In Study 2, we employed three OAE types: CEOAEs ( n = 16 TD, 21 LiD), stimulus frequency OAEs ( n = 21 TD, 30 LiD), and distortion product OAEs ( n = 17 TD, 22 LiD) in a contralateral noise paradigm. Results from both studies suggest that the MOCR functioning is not significantly d...
Speech perception in a noisy environment is a significant challenge for individuals with auditory... more Speech perception in a noisy environment is a significant challenge for individuals with auditory processing deficits. Evidence exists that exaggerating the slow temporal modulations may enhance speech perception for these individuals in the absence or presence of background noise. Nevertheless, a comprehensive assessment of envelope enhancement algorithms is lacking. In the present research study, two different schemes of envelope enhancement (dynamic and static) were evaluated subjectively and objectively for different types and levels of background noise with and without applying a noise reduction algorithm. In the subjective assessment, the dynamic envelope enhancement algorithm was evaluated with three different subjective groups including, twelve normal adults, twelve normal children, and eleven children with suspected auditory processing disorder (APD). The subjective results revealed that the speech intelligibility scores were lower for APD subjects compared to both normal adults and normal children. The subjective results also demonstrated that enhancing the temporal envelope is much more beneficial for subjects with suspected APD when compared to normal adults and children participating in the subjective experiment. In the objective assessment, the Hearing Aid Speech Perception Index (HASPI) was employed to predict the speech intelligibility scores which correlated highly with the subjective data. Comprehensive objective experiments demonstrated that both dynamic and static envelope enhancement algorithms are only effective in improving speech perception under certain processing conditions that depended on the type, level and location of the background noise. It is also shown that the application of a noise reduction algorithm prior to the envelope enhancement algorithms will increase their range of effectiveness.
A Sound Foundation Through Early Amplification, 2007
It is always difficult to describe what we mean when we discuss auditory processing disorders. Th... more It is always difficult to describe what we mean when we discuss auditory processing disorders. There are many different interpretations of what such a disorder looks like, what tests should be used to diagnose it, where the difficulties lie anatomically or ...
The Journal of the Acoustical Society of America, 1999
This paper considers an acoustic basis for speech intelligibility and evaluates various acoustica... more This paper considers an acoustic basis for speech intelligibility and evaluates various acoustically based speech intelligibility prediction algorithms. Earlier research indicates that speech intelligibility does not require preservation of spectral and temporal fine‐structure, but is highly dependent on the preservation of the amplitude component of the modulation spectrum [R. Drullman, J. Acoust. Soc. Am. 97, 585–592 (1995)]. This study assessed the importance of the phase component of the modulation spectrum using a 21‐alternative forced‐choice consonant perception test. Temporal and spectral fine‐structure were removed by modulating a white noise carrier with 50 Hz low‐pass filtered speech amplitude envelopes in 4, 8, or 24 discrete bands. Modulation spectrum phase was distorted by imposing a random delay in each discrete band. Behavioral results are discussed in light of intelligibility predictions generated by the articulation index [N. R. French and J. C. Steinberg, J. Acoust. Soc. Am. 19, 90–119 (...
Behavioral manifestations of processing deficits associated with auditory processing disor-der (A... more Behavioral manifestations of processing deficits associated with auditory processing disor-der (APD) have been well documented. However, little is known about their anatomical underpinnings, especially cochlear processing. Cochlear delays, a proxy for cochlear tun-ing, measured using stimulus frequency otoacoustic emission (SFOAE) group delay, and the influence of the medial olivocochlear (MOC) system activation at the auditory periphery was studied in 23 children suspected with APD (sAPD) and 22 typically developing (TD) children. Results suggest that children suspected with APD have longer SFOAE group delays (possibly due to sharper cochlear tuning) and reduced MOC function compared to TD children. Other differences between the groups include correlation between MOC func-tion and SFOAE delay in quiet in the TD group, and lack thereof in the sAPD group. MOC-mediated changes in SFOAE delay were in opposite directions between groups: increase in delay in TD vs. reduction in delay in ...
Purpose A growing body of evidence indicates that treatment of hearing loss by provision of heari... more Purpose A growing body of evidence indicates that treatment of hearing loss by provision of hearing aids leads to improvements in auditory and visual working memory. The purpose of this study was to assess whether similar working memory benefits are observed following provision of cochlear implants (CIs). Method Fifteen adults with postlingually acquired severe bilateral sensorineural hearing loss completed the prospective longitudinal study. Participants were candidates for bilateral cochlear implantation with some aidable hearing in each ear. Implantation surgeries were carried out sequentially, approximately 1 year apart. Working memory was measured with the visual Reading Span Test (Daneman & Carpenter, 1980) at 5 time points: pre-operatively following a 6-month bilateral hearing aid trial, after 6 and 12 months of bimodal (CI plus contralateral hearing aid) listening experience following the 1st CI surgery and activation, and again after 6 and 12 months of bilateral CI listenin...
The test battery typically used for the diagnosis of auditory processing disorder (APD) is highly... more The test battery typically used for the diagnosis of auditory processing disorder (APD) is highly heterogeneous, with an emphasis on the central auditory nervous system. As such, the peripheral auditory system is typically only screened for the presence of an overt hearing loss. Our previous work suggested that children suspected of APD (sAPD) have atypically sharp cochlear tuning when measured using stimulus frequency otoacoustic emission (SFOAE) group delay. In the present work, we extend our previous findings and test the hypothesis that cochlear tuning influences auditory brainstem response (ABR) latencies. Our hypothesis is based on filter theory, which suggests that a sharper filter will take longer to build-up and ring longer. We predicted that sharper cochlear filters in sAPD should result in delayed ABR wave latencies and will be associated with poorer performance on speech perception tests. Preliminary data from 16 sAPD and 6 typically developing children show a positive correlation between coch...
Background: The ASHA recommends including electrophysiological measures in an auditory processing... more Background: The ASHA recommends including electrophysiological measures in an auditory processing disorder (APD) assessment battery, but few audiologists do so, potentially because of limited published evidence for its utility. Purpose: This study compared the auditory brainstem responses (ABRs) of children with APD with agematched children and adults. Study Sample: This study retrospectively examined the records of 108 children suspected of APD (sAPD) who had click-evoked ABRs recorded as part of their clinical assessment. Twenty adults and 22 typically developing (TD) children were recruited as controls. Data collection and Analysis: Click-evoked ABRs were recorded at slow (13.3 clicks/sec) and faster (57.7 clicks/sec) stimulation rates. ABRs were analyzed using typical clinical measures (latencies and interpeak intervals for waves I, III, and V) and using a model proposed by Ponton et al that offered a more detailed analysis of axonal conduction time and synaptic transmission delay. Results: Both clinical measures and the Ponton model analysis showed no significant differences between TD children and adults. Children sAPD showed absolute latencies that were significantly prolonged when compared with adults but not when compared with TD children. But individual children sAPD showed clinically significant delays (.2 standard deviations of TD children's data). Examination of responses delineating axonal versus synaptic transmission showed significant delays in synaptic transmission in the group of children sAPD in comparison to TD children and adults. These results suggest that a significant portion of children with listening difficulties showed evidence of reduced or atypical brainstem functioning. Examining the responses for axonal and synaptic delays revealed evidence of a synaptic pattern of abnormalities in a significant portion (37.03%) of children sAPD. Such observations could provide objective evidence of factors potentially contributing to listening difficulties that are frequently reported in children identified with APD. Conclusions: Children sAPD often showed abnormalities in the ABR, suggesting a neurophysiologic origin of their reported difficulties, frequently originating at or before the first synapse. This study provides supportive evidence for the value of click-evoked ABRs in comprehensive auditory processing assessment batteries.
Abstract Objective: The purpose of this study was to examine developmental trends in spectral rip... more Abstract Objective: The purpose of this study was to examine developmental trends in spectral ripple discrimination (SRD) and to compare the performance of typically developing children to children with auditory processing disorder (APD). Study design: Cross-sectional study. Study sample: Fifteen children with APD, as well as 17 typically developing children and 14 adults reporting no listening or academic difficulties participated. Results: Typically developing children showed poor SRD thresholds compared to adults, indicating prolonged maturation of spectral shape recognition. Both typically developing children and APD children showed a maturational trend in SRD, but a General Linear Model fit to their thresholds showed that children with APD displayed SRD thresholds that were significantly poorer than those of typically developing children when controlling for age. This suggests that in APD children, SRD maturation lags behind typically developing children. Conclusion: Poor spectral ripple discrimination may explain some of the listening difficulties experienced by children with APD.
OBJECTIVES We sought to investigate whether children referred to our audiology clinic with a comp... more OBJECTIVES We sought to investigate whether children referred to our audiology clinic with a complaint of listening difficulty, that is, suspected of auditory processing disorder (APD), have difficulties localizing sounds in noise and whether they have reduced benefit from spatial release from masking. DESIGN Forty-seven typically hearing children in the age range of 7 to 17 years took part in the study. Twenty-one typically developing (TD) children served as controls, and the other 26 children, referred to our audiology clinic with listening problems, were the study group: suspected APD (sAPD). The ability to localize a speech target (the word "baseball") was measured in quiet, broadband noise, and speech-babble in a hemi-anechoic chamber. Participants stood at the center of a loudspeaker array that delivered the target in a diffused noise-field created by presenting independent noise from four loudspeakers spaced 90° apart starting at 45°. In the noise conditions, the signal-to-noise ratio was varied between -12 and 0 dB in 6-dB steps by keeping the noise level constant at 66 dB SPL and varying the target level. Localization ability was indexed by two metrics, one assessing variability in lateral plane [lateral scatter (Lscat)] and the other accuracy in the front/back dimension [front/back percent correct (FBpc)]. Spatial release from masking (SRM) was measured using a modified version of the Hearing in Noise Test (HINT). In this HINT paradigm, speech targets were always presented from the loudspeaker at 0°, and a single noise source was presented either at 0°, 90°, or 270° at 65 dB A. The SRM was calculated as the difference between the 50% correct HINT speech reception threshold obtained when both speech and noise were collocated at 0° and when the noise was presented at either 90° or 270°. RESULTS As expected, in both groups, localization in noise improved as a function of signal-to-noise ratio. Broadband noise caused significantly larger disruption in FBpc than in Lscat when compared with speech babble. There were, however, no group effects or group interactions, suggesting that the children in the sAPD group did not differ significantly from TD children in either localization metric (Lscat and FBpc). While a significant SRM was observed in both groups, there were no group effects or group interactions. Collectively, the data suggest that children in the sAPD group did not differ significantly from the TD group for either binaural measure investigated in the study. CONCLUSIONS As is evident from a few poor performers, some children with listening difficulties may have difficulty in localizing sounds and may not benefit from spatial separation of speech and noise. However, the heterogeneity in APD and the variability in our data do not support the notion that localization is a global APD problem. Future studies that employ a case study design might provide more insights.
Dynamics of spontaneous alpha activity correlate with language ability in young children" (2019).... more Dynamics of spontaneous alpha activity correlate with language ability in young children" (2019). Communication Sciences and Disorders Publications. 17.
Journal of the American Academy of Audiology, 2017
Previous studies have suggested elevated reflex thresholds in children with auditory processing d... more Previous studies have suggested elevated reflex thresholds in children with auditory processing disorders (APDs). However, some aspects of the child's ear such as ear canal volume and static compliance of the middle ear could possibly affect the measurements of reflex thresholds and thus impact its interpretation. Sound levels used to elicit reflexes in a child's ear may be higher than predicted by calibration in a standard 2-cc coupler, and lower static compliance could make visualization of very small changes in impedance at threshold difficult. For this purpose, it is important to evaluate threshold data with consideration of differences between children and adults. A set of studies were conducted. The first compared reflex thresholds obtained using standard clinical procedures in children with suspected APD to that of typically developing children and adults to test the replicability of previous studies. The second study examined the impact of ear canal volume on estimat...
The Journal of the Acoustical Society of America, 2016
Children as young as 5 yr old localize sounds as accurately as adults in quiet in the frontal hem... more Children as young as 5 yr old localize sounds as accurately as adults in quiet in the frontal hemifield. However, children's ability to localize in noise and in the front/back (F/B) dimension are scantily studied. To address this, the first part of this study investigated localization-in-noise ability of children vs young adults in two maskers: broadband noise (BBN) and speech-babble (SB) at three signal-to-noise ratios: -12, -6, and 0 dB. In the second part, relationship between binaural medial olivocochlear system (MOC) function and localization-in-noise was investigated. In both studies, 21 children and 21 young adults participated. Results indicate, while children are able to differentiate sounds arriving in the F/B dimension on par with adults in quiet and in BBN, larger differences were found for SB. Accuracy of children's localization in noise (for both maskers) in the lateral plane was also poorer than adults'. Significant differences in binaural MOC interaction (mBIC; the difference between the sum of two monaural- and binaural-MOC strength) between adults and children were also found. For reasons which are not clear, adult F/B localization in BBN correlates better with mBIC while children's F/B localization in SB correlated better with binaural MOC strength.
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Papers by Prudence Allen