Evaluation of Auditory Evoked Potentials as a Hearing aid Outcome Measure

This thesis aimed to explore the applicability of Cortical Auditory Evoked Potentials (CAEPs) and Envelope Following Responses (EFRs) as objective aided outcome measures for use in infants wearing hearing aids. The goals for CAEP-related projects were to evaluate the effect of speech stimulus source on CAEPs, non-linear hearing aid processing on tone-evoked CAEPs, and the effect of inter-stimulus intervals on non-linear hearing aid processing of phonemes. Results illustrated larger amplitude CAEPs with shorter latencies for speech stimuli from word-medial positions than word-initial positions, and no significant effect of the tone burst onset overshoot due to non-linear hearing aid processing. Inter-stimulus intervals in CAEP protocols resulted in significantly lower aided phoneme levels compared to when they occurred in running speech, illustrating potential inaccuracies in representation of relevant hearing aid function during testing. The major contribution of this thesis includes the proposal and validation of a test paradigm based on speech-evoked EFRs for use as an objective aided outcome measure. The stimulus is a naturally spoken token /susashi/ modified to enable recording of eight EFRs from low, mid and high frequency regions. The projects aimed to evaluate previously recommended response analysis methods of averaging responses to opposite polarities for vowel-evoked EFRs as well as sensitivity of the proposed paradigm to changes in audibility due to level and bandwidth in adults with normal hearing and additionally, due to amplification in adults with hearing loss. Results demonstrated a vowel-specific effect of averaging opposite polarity responses when the first harmonic was present, however the averaging did not affect detection in the majority of participants. The EFR test paradigm illustrated carrier-specific changes in audibility due to level, bandwidth and amplification suggesting that the paradigm may be a useful tool in evaluating unaided and aided audibility, and therefore appropriateness of hearing aid fittings. Further validation is necessary in infants and children wearing hearing aids. In conclusion, CAEPs and EFRs vary in strengths and limitations, and therefore it is likely that a combination of measures may be necessary to address the variety of hearing disorders seen in a typical audiological caseload

A Pilot Study on Cortical Auditory Evoked Potentials in Children: Aided CAEPs Reflect Improved High-Frequency Audibility with Frequency Compression Hearing Aid Technology

Background. This study investigated whether cortical auditory evoked potentials (CAEPs) could reliably be recorded and interpreted using clinical testing equipment, to assess the effects of hearing aid technology on the CAEP. Methods. Fifteen normal hearing (NH) and five hearing impaired (HI) children were included in the study. NH children were tested unaided; HI children were tested while wearing hearing aids. CAEPs were evoked with tone bursts presented at a suprathreshold level. Presence/absence of CAEPs was established based on agreement between two independent raters. Results. Present waveforms were interpreted for most NH listeners and all HI listeners, when stimuli were measured to be at an audible level. The younger NH children were found to have significantly different waveform morphology, compared to the older children, with grand averaged waveforms differing in the later part of the time window (the N2 response). Results suggest that in some children, frequency compression hearing aid processing improved audibility of specific frequencies, leading to increased rates of detectable cortical responses in HI children. Conclusions. These findings provide support for the use of CAEPs in measuring hearing aid benefit. Further research is needed to validate aided results across a larger group of HI participants and with speech-based stimuli

Protocol for the Provision of Amplification v 2023.01

This Protocol addresses the provision of amplification (hereafter: \u27Amplification\u27) to infants and children who are receiving services from the Ontario Infant Hearing Program (IHP). For the purposes of this protocol, providing amplification includes the processes of prescribing a hearing aid (air or bone conduction) and/or other hearing assistance technologies based on appropriate assessment information, verification that the specified acoustical performance targets have been achieved, fitting the device on the child, and ongoing evaluation of device effectiveness in daily life. Amplification within the IHP does not include the provision of cochlear implants

Investigating potential interactions between envelope following responses elicited simultaneously by different vowel formants

Envelope following responses (EFRs) evoked by the periodicity of voicing in vowels are elicited at the fundamental frequency of voice (f0), irrespective of the harmonics that initiate it. One approach of improving the frequency specificity of vowel stimuli without increasing test-time is by altering the f0 selectively in one or more formants. The harmonics contributing to an EFR can then be differentiated by the unique f0 at which the EFRs are elicited. The advantages of using such an approach would be increased frequency specificity and efficiency, given that multiple EFRs can be evaluated in a certain test-time. However, multiple EFRs elicited simultaneously could interact and lead to altered amplitudes and outcomes. To this end, the present study aimed to evaluate: (i) if simultaneous recording of two EFRs, one elicited by harmonics in the first formant (F1) and one elicited by harmonics in the second and higher formants (F2+), leads to attenuation or enhancement of EFR amplitude, and (ii) if simultaneous measurement of two EFRs affects its accuracy and anticipated efficiency. In a group of 22 young adults with normal hearing, EFRs were elicited by F1 and F2+ bands of /u/, /a/ and /i/ when F1 and F2+ were presented independently (individual), when F1 and F2+ were presented simultaneously (dual), and when F1 or F2+ was presented with spectrally matched Gaussian noise of the other (noise). Repeated-measures analysis of variance indicated no significant group differences in EFR amplitudes between any of the conditions, suggesting minimal between-EFR interactions. Between-participant variability was evident, however, significant changes were evident only in a third of the participants for the stimulus /u/ F1. For the majority of stimuli, the change between individual and dual conditions was positively correlated with the change between individual and noise conditions, suggesting that interaction-based changes in EFR amplitude, when present, were likely due to the restriction of cochlear regions of excitation in the presence of a competing stimulus. The amplitude of residual noise was significantly higher in the dual or noise relative to the individual conditions, although the mean differences were very small (\u3c3 nV). F-test-based detection of EFRs, commonly used to determine the presence of an EFR, did not vary across conditions. Further, neither the mean reduction in EFR amplitude nor the mean increase in noise amplitude in dual relative to individual conditions was large enough to alter the anticipated gain in efficiency of simultaneous EFR recordings. Together, results suggest that the approach of simultaneously recording two vowel-evoked EFRs from different formants for improved frequency-specificity does not alter test accuracy and is more time-efficient than evaluating EFRs to each formant individually

The ling 6(HL) test: Typical pediatric performance data and clinical use evaluation

Background: The Ling 6(HL) test offers a calibrated version of naturally produced speech sounds in dB HL for evaluation of detection thresholds. Aided performance has been previously characterized in adults.Purpose: The purpose of this work was to evaluate and refine the Ling 6(HL) test for use in pediatric hearing aid outcome measurement.Research Design: This work is presented across two studies incorporating an integrated knowledge translation approach in the characterization of normative and typical performance, and in the evaluation of clinical feasibility, utility, acceptability, and implementation.Study Sample: A total of 57 children, 28 normally hearing and 29 with binaural sensorineural hearing loss, were included in Study 1. Children wore their own hearing aids fitted using Desired Sensation Level v5.0. Nine clinicians from The Network of Pediatric Audiologists participated in Study 2.Data Collection and Analysis: A CD-based test format was used in the collection of unaided and aided detection thresholds in laboratory and clinical settings; thresholds were measured clinically as part of routine clinical care. Confidence intervals were derived to characterize normal performance and typical aided performance according to hearing loss severity. Unaided-aided performance was analyzed using a repeated-measures analysis of variance. The audiologists completed an online questionnaire evaluating the quality, feasibility/executability, utility/comparative value/relative advantage, acceptability/applicability, and interpretability, in addition to recommendation and general comments sections.Results: Ling 6(HL) thresholds were reliably measured with children 3-18 yr old. Normative and typical performance ranges were translated into a scoring tool for use in pediatric outcome measurement. In general, questionnaire respondents generally agreed that the Ling 6(HL) test was a high-quality outcome evaluation tool that can be implemented successfully in clinical settings.Conclusions: By actively collaborating with pediatric audiologists and using an integrated knowledge translation framework, this work supported the creation of an evidence-based clinical tool that has the potential to be implemented in, and useful to, clinical practice. More research is needed to characterize performance in alternative listening conditions to facilitate use with infants, for example. Future efforts focused on monitoring the use of the Ling 6(HL) test in daily clinical practice may help describe whether clinical use has been maintained across time and if any additional adaptations are necessary to facilitate clinical uptake

Electroacoustic Comparison of Hearing Aid Output of Phonemes in Running Speech versus Isolation: Implications for Aided Cortical Auditory Evoked Potentials Testing

Background. Functioning of nonlinear hearing aids varies with characteristics of input stimuli. In the past decade, aided speech evoked cortical auditory evoked potentials (CAEPs) have been proposed for validation of hearing aid fittings. However, unlike in running speech, phonemes presented as stimuli during CAEP testing are preceded by silent intervals of over one second. Hence, the present study aimed to compare if hearing aids process phonemes similarly in running speech and in CAEP testing contexts. Method. A sample of ten hearing aids was used. Overall phoneme level and phoneme onset level of eight phonemes in both contexts were compared at three input levels representing conversational speech levels. Results. Differences of over 3 dB between the two contexts were noted in one-fourth of the observations measuring overall phoneme levels and in one-third of the observations measuring phoneme onset level. In a majority of these differences, output levels of phonemes were higher in the running speech context. These differences varied across hearing aids. Conclusion. Lower output levels in the isolation context may have implications for calibration and estimation of audibility based on CAEPs. The variability across hearing aids observed could make it challenging to predict differences on an individual basis

Translation and adaptation of five English language self-report health measures to South Indian Kannada language

The objective of this study was to translate and adapt five English self-report health measures to a South Indian language Kannada. Currently, no systematically developed questionnaires assessing hearing rehabilitation outcomes are available for clinical or research use in Kannada. The questionnaires included for translation and adaptation were the hearing handicap questionnaire, the international outcome inventory- hearing aids, the self-assessment of communication, the participation scale, and the assessment of quality of life 4 dimensions. The questionnaires were translated and adapted using the American Association of Orthopedic Surgeons (AAOS) guidelines. The five stages followed in the study included: i) forward translation; ii) common translation synthesis; iii) backward translation; iv) expert committee review; v) pre-final testing. In this paper, in addition to a description of the process, we also highlight practical issues faced while adopting the procedure with an aim to help readers better understand the intricacies involved in such processes. This can be helpful to researchers and clinicians who are keen to adapt standard self-report questionnaires from other languages to their native language

The effect of stimulus choice on cortical auditory evoked potentials (CAEP): Consideration of speech segment positioning within naturally produced speech

Objective: Cortical auditory evoked potentials (CAEPs) can be elicited to stimuli generated from different parts of speech. The aim of this study was to compare the phoneme/s/from word medial and word initial positions and its influence on the CAEP. Design: Stimuli from word medial positions were found to have shorter rise times compared to the same phonemes from word initial positions. A repeated measures design was carried out with CAEPs elicited using/s/from a word initial and a word medial position. Study sample: Sixteen individuals with audiometric thresholds within normal limits participated in the study. Results: Stimuli/s/from a word medial position elicited CAEPs with significantly larger amplitudes and shorter latencies compared to/s/from a word initial position (p \u3c 0.05). Conclusions: Findings from this study, incorporating naturally produced speech sounds, suggest the need to consider spectral and temporal variations when choosing stimuli to optimize the amplitude and latency characteristics of the CAEP. Overall, findings illustrate good test-retest reliability of CAEP measures using speech stimuli with clinical equipment. © 2012 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society