RP206 - A Comparison of Remote Microphone Technologies for Pediatric Hearing Aid Users

Abstract:
Remote microphone systems (RMS) are tools designed to improve signal-to-noise ratios (SNRs) in the classroom, but there are differences in how they function. Twenty-five pediatric hearing aid users with mild to severe hearing losses were evaluated in a simulated classroom comparing a dual adaptive system to a fixed directional system at +4, +2 and -2 dB SNRs in a teacher/lecture and small group setting. Results indicate significant differences between the two technologies in terms of speech intelligibility and subjective preference. Performance and preference will be reviewed, and evidence-based treatment recommendations shared in this research presentation.

Summary:
Rationale/Purpose
Children with hearing loss require a favorable SNR of +15 dB or greater to access the academic curriculum. Children spend a considerable amount of their day listening in classrooms with poor SNRs (Crukley et al, 2011). RMS are designed to improve SNRs in these settings, but there are differences in how each technology functions, which may lead to differences in recommendations for use. The purpose of this study is to: 1) compare speech intelligibility in noise performance in school-age children with hearing loss across two different types of RMS: a dual adaptive system and a traditional fixed directional system in both a teacher/lecture setting and a small group setting, and 2) evaluate preference between the dual adaptive RMS and the fixed directional RMS based on sound quality, comfort in noise, clarity of speech, ease of use, aesthetics, and overall preference.

Methods
Twenty-five experienced hearing aid users, ages 8-12, with mild to severe hearing losses were included. Study hearing aids were programmed and verified to prescriptive target and program settings were set to fixed directional. Participants were then tested in a simulated classroom at +4, +2, and -2 dB SNR without the RMS, with the dual adaptive RMS, and with the fixed directional RMS in two different conditions: teacher/lecture and small group settings.

Speech stimuli for the teacher condition was presented 8.5 feet from the participant at 0 degrees azimuth, and the RMS was placed 8 inches from the diaphragm of the speaker. For the small group condition, the participant was seated at a small table with 3 speakers, placed 2 feet away with the remote microphone placed on the center of the table. For both conditions, diffuse classroom noise was played from four corner speakers placed ~ 3m from the participant. Study order was randomized and counter-balanced to avoid order effects. A repeated measures ANOVA was run to analyze speech intelligibility for both conditions.

Results
Speech intelligibility was improved with the addition of any RMS compared to the no RMS condition. In the teacher condition, performance between RMS was no different at +4 dB SNR, but the dual adaptive system significantly outperformed the fixed directional system at a +2 and -2 dB SNR. In the small group condition, speech understanding was best with the dual adaptive system across all SNRs. Participants exhibited a preference for the dual adaptive system related to comfort in noise, clarity of speech, sound quality, and overall preference.

Conclusions
Both RMS provided improvement in speech intelligibility over the no RM condition. The dual adaptive RMS outperformed the fixed directional RMS in most listening conditions for both teacher and small group conditions, especially as the SNR decreased. Participants also demonstrated a subjective preference for the dual adaptive system. The dual adaptive technology should be considered for classroom use over the fixed directional technology, especially in adverse listening environments.

Intermediate instructional level was chosen because this study builds on existing knowledge about RMS and expands on treatment recommendations.

Brief Summary of Clinical Takeaways:
The clinical takeaway for this session is remote microphone technologies vary in functionality and performance. Audiologists should counsel patients on the differences between the two technologies in terms of performance and useability to optimize outcomes in the classroom and beyond.