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Hearing Disorders: HELP
Articles by Vijay Parsa
Based on 4 articles published since 2010
(Why 4 articles?)
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Between 2010 and 2020, Vijay Parsa wrote the following 4 articles about Hearing Disorders.
 
+ Citations + Abstracts
1 Article Fitting Frequency-Lowering Signal Processing Applying the American Academy of Audiology Pediatric Amplification Guideline: Updates and Protocols. 2016

Scollie, Susan / Glista, Danielle / Seto, Julie / Dunn, Andrea / Schuett, Brittany / Hawkins, Marianne / Pourmand, Nazanin / Parsa, Vijay. ·National Centre for Audiology, Faculty of Health Sciences, Western University, London, Ontario, Canada. · Microsoft Corporation, Redmond, WA. · Dunn Audiology, London, Ontario, Canada. · Cambridge Audiology, Cambridge, Ontario, Canada. · Knowles Electronics, Valencia, CA. ·J Am Acad Audiol · Pubmed #26967363.

ABSTRACT: BACKGROUND: Although guidelines for fitting hearing aids for children are well developed and have strong basis in evidence, specific protocols for fitting and verifying technologies can supplement such guidelines. One such technology is frequency-lowering signal processing. Children require access to a broad bandwidth of speech to detect and use all phonemes including female /s/. When access through conventional amplification is not possible, the use of frequency-lowering signal processing may be considered as a means to overcome limitations. Fitting and verification protocols are needed to better define candidacy determination and options for assessing and fine tuning frequency-lowering signal processing for individuals. PURPOSE: This work aims to (1) describe a set of calibrated phonemes that can be used to characterize the variation in different brands of frequency-lowering processors in hearing aids and the verification with these signals and (2) determine whether verification with these signal are predictive of perceptual changes associated with changes in the strength of frequency-lowering signal processing. Finally, we aimed to develop a fitting protocol for use in pediatric clinical practice. STUDY SAMPLE: Study 1 used a sample of six hearing aids spanning four types of frequency lowering algorithms for an electroacoustic evaluation. Study 2 included 21 adults who had hearing loss (mean age 66 yr). DATA COLLECTION AND ANALYSIS: Simulated fricatives were designed to mimic the level and frequency shape of female fricatives extracted from two sources of speech. These signals were used to verify the frequency-lowering effects of four distinct types of frequency-lowering signal processors available in commercial hearing aids, and verification measures were compared to extracted fricatives made in a reference system. In a second study, the simulated fricatives were used within a probe microphone measurement system to verify a wide range of frequency compression settings in a commercial hearing aid, and 27 adult listeners were tested at each setting. The relation between the hearing aid verification measures and the listener's ability to detect and discriminate between fricatives was examined. RESULTS: Verification measures made with the simulated fricatives agreed to within 4 dB, on average, and tended to mimic the frequency response shape of fricatives presented in a running speech context. Some processors showed a greater aided response level for fricatives in running speech than fricatives presented in isolation. Results with listeners indicated that verified settings that provided a positive sensation level of /s/ and that maximized the frequency difference between /s/ and /∫/ tended to have the best performance. CONCLUSIONS: Frequency-lowering signal processors have measureable effects on the high-frequency fricative content of speech, particularly female /s/. It is possible to measure these effects either with a simple strategy that presents an isolated simulated fricative and measures the aided frequency response or with a more complex system that extracts fricatives from running speech. For some processors, a more accurate result may be achieved with a running speech system. In listeners, the aided frequency location and sensation level of fricatives may be helpful in predicting whether a specific hearing aid fitting, with or without frequency-lowering, will support access to the fricatives of speech.

2 Article Effect of Stimulus Level and Bandwidth on Speech-Evoked Envelope Following Responses in Adults With Normal Hearing. 2015

Easwar, Vijayalakshmi / Purcell, David W / Aiken, Steven J / Parsa, Vijay / Scollie, Susan D. ·1National Centre for Audiology, Western University, London, Ontario, Canada; 2School of Communication Sciences and Disorders, Western University, London, Ontario, Canada; and 3School of Human Communication Disorders, Dalhousie University, Halifax, Nova Scotia, Canada. ·Ear Hear · Pubmed #26226607.

ABSTRACT: OBJECTIVE: The use of auditory evoked potentials as an objective outcome measure in infants fitted with hearing aids has gained interest in recent years. This article proposes a test paradigm using speech-evoked envelope following responses (EFRs) for use as an objective-aided outcome measure. The method uses a running speech-like, naturally spoken stimulus token /susa∫i/ (fundamental frequency [f0] = 98 Hz; duration 2.05 sec), to elicit EFRs by eight carriers representing low, mid, and high frequencies. Each vowel elicited two EFRs simultaneously, one from the region of formant one (F1) and one from the higher formants region (F2+). The simultaneous recording of two EFRs was enabled by lowering f0 in the region of F1 alone. Fricatives were amplitude modulated to enable recording of EFRs from high-frequency spectral regions. The present study aimed to evaluate the effect of level and bandwidth on speech-evoked EFRs in adults with normal hearing. As well, the study aimed to test convergent validity of the EFR paradigm by comparing it with changes in behavioral tasks due to bandwidth. DESIGN: Single-channel electroencephalogram was recorded from the vertex to the nape of the neck over 300 sweeps in two polarities from 20 young adults with normal hearing. To evaluate the effects of level in experiment I, EFRs were recorded at test levels of 50 and 65 dB SPL. To evaluate the effects of bandwidth in experiment II, EFRs were elicited by /susa∫i/ low-pass filtered at 1, 2, and 4 kHz, presented at 65 dB SPL. The 65 dB SPL condition from experiment I represented the full bandwidth condition. EFRs were averaged across the two polarities and estimated using a Fourier analyzer. An F test was used to determine whether an EFR was detected. Speech discrimination using the University of Western Ontario Distinctive Feature Differences test and sound quality rating using the Multiple Stimulus Hidden Reference and Anchors paradigm were measured in identical bandwidth conditions. RESULTS: In experiment I, the increase in level resulted in a significant increase in response amplitudes for all eight carriers (mean increase of 14 to 50 nV) and the number of detections (mean increase of 1.4 detections). In experiment II, an increase in bandwidth resulted in a significant increase in the number of EFRs detected until the low-pass filtered 4 kHz condition and carrier-specific changes in response amplitude until the full bandwidth condition. Scores in both behavioral tasks increased with bandwidth up to the full bandwidth condition. The number of detections and composite amplitude (sum of all eight EFR amplitudes) significantly correlated with changes in behavioral test scores. CONCLUSIONS: Results suggest that the EFR paradigm is sensitive to changes in level and audible bandwidth. This may be a useful tool as an objective-aided outcome measure considering its running speech-like stimulus, representation of spectral regions important for speech understanding, level and bandwidth sensitivity, and clinically feasible test times. This paradigm requires further validation in individuals with hearing loss, with and without hearing aids.

3 Article Evaluation of Speech-Evoked Envelope Following Responses as an Objective Aided Outcome Measure: Effect of Stimulus Level, Bandwidth, and Amplification in Adults With Hearing Loss. 2015

Easwar, Vijayalakshmi / Purcell, David W / Aiken, Steven J / Parsa, Vijay / Scollie, Susan D. ·1National Centre for Audiology, Western University, London, Ontario, Canada; 2School of Communication Sciences and Disorders, Western University, London, Ontario, Canada; and 3School of Human Communication Disorders, Dalhousie University, Halifax, Nova Scotia, Canada. ·Ear Hear · Pubmed #26226606.

ABSTRACT: OBJECTIVES: The present study evaluated a novel test paradigm based on speech-evoked envelope following responses (EFRs) as an objective aided outcome measure for individuals fitted with hearing aids. Although intended for use in infants with hearing loss, this study evaluated the paradigm in adults with hearing loss, as a precursor to further evaluation in infants. The test stimulus was a naturally male-spoken token /susa∫i/, modified to enable recording of eight individual EFRs, two from each vowel for different formants and one from each fricative. In experiment I, sensitivity of the paradigm to changes in audibility due to varying stimulus level and use of hearing aids was tested. In experiment II, sensitivity of the paradigm to changes in aided audible bandwidth was evaluated. As well, experiment II aimed to test convergent validity of the EFR paradigm by comparing the effect of bandwidth on EFRs and behavioral outcome measures of hearing aid fitting. DESIGN: Twenty-one adult hearing aid users with mild to moderately severe sensorineural hearing loss participated in the study. To evaluate the effects of level and amplification in experiment I, the stimulus was presented at 50 and 65 dB SPL through an ER-2 insert earphone in unaided conditions and through individually verified hearing aids in aided conditions. Behavioral thresholds of EFR carriers were obtained using an ER-2 insert earphone to estimate sensation level of EFR carriers. To evaluate the effect of aided audible bandwidth in experiment II, EFRs were elicited by /susa∫i/ low-pass filtered at 1, 2, and 4 kHz and presented through the programmed hearing aid. EFRs recorded in the 65 dB SPL aided condition in experiment I represented the full bandwidth condition. EEG was recorded from the vertex to the nape of the neck over 300 sweeps. Speech discrimination using the University of Western Ontario Distinctive Feature Differences test and sound quality rating using the Multiple-Stimulus Hidden Reference and Anchor paradigm were measured in the same bandwidth conditions. RESULTS: In experiment I, an increase in stimulus level above threshold and the use of amplification resulted in a significant increase in the number of EFRs detected per condition. At positive sensation levels, an increase in level demonstrated a significant increase in response amplitude in unaided and aided conditions. At 50 and 65 dB SPL, the use of amplification led to a significant increase in response amplitude for the majority of carriers. In experiment II, the number of EFR detections and the combined response amplitude of all eight EFRs improved with an increase in bandwidth up to 4 kHz. In contrast, behavioral measures continued to improve at wider bandwidths. Further change in EFR parameters was possibly limited by the hearing aid bandwidth. Significant positive correlations were found between EFR parameters and behavioral test scores in experiment II. CONCLUSIONS: The EFR paradigm demonstrates sensitivity to changes in audibility due to a change in stimulus level, bandwidth, and use of amplification in clinically feasible test times. The paradigm may thus have potential applications as an objective aided outcome measure. Further investigations exploring stimulus-response relationships in aided conditions and validation studies in children are warranted.

4 Article Predicting the perceived sound quality of frequency-compressed speech. 2014

Huber, Rainer / Parsa, Vijay / Scollie, Susan. ·Centre of Competence HörTech gGmbH, Oldenburg, Germany; Cluster of Excellence Hearing4All, Oldenburg and Hannover, Germany. · National Centre for Audiology, Western University, London, Canada. ·PLoS One · Pubmed #25402456.

ABSTRACT: The performance of objective speech and audio quality measures for the prediction of the perceived quality of frequency-compressed speech in hearing aids is investigated in this paper. A number of existing quality measures have been applied to speech signals processed by a hearing aid, which compresses speech spectra along frequency in order to make information contained in higher frequencies audible for listeners with severe high-frequency hearing loss. Quality measures were compared with subjective ratings obtained from normal hearing and hearing impaired children and adults in an earlier study. High correlations were achieved with quality measures computed by quality models that are based on the auditory model of Dau et al., namely, the measure PSM, computed by the quality model PEMO-Q; the measure qc, computed by the quality model proposed by Hansen and Kollmeier; and the linear subcomponent of the HASQI. For the prediction of quality ratings by hearing impaired listeners, extensions of some models incorporating hearing loss were implemented and shown to achieve improved prediction accuracy. Results indicate that these objective quality measures can potentially serve as tools for assisting in initial setting of frequency compression parameters.