The speech intelligibility benefit of a unilateral wireless system for hearing-impaired adults

Abstract

Objective: This study measured the effects of two previously untested practical considerations - venting and transmission delays - on speech intelligibility in a simulated unilateral wireless system, where a target signal in background noise was transmitted wirelessly to the hearing-impaired (HI) listener. Design: Speech reception thresholds (SRTs) relative to the signal-to-noise ratio (SNR) were measured by varying the surrounding babble noise level. The target signal was presented at 0 azimuth in the soundfi eld and unilaterally via an insert earphone, using open and closed fi ttings with simulated-wireless delays ranging between 0 - 160 ms. SRTs were also measured unaided and with participants ' current hearing aid(s). Study sample: Thirty-three mild-to-moderate sensorineural HI adults participated in the experiment. Results: For an open fi tting, the results showed a 5-dB SNR benefi t in SRT compared to unaided performance at shorter delays. For a closed fi tting, the majority of participants could accurately recognize speech below 20 dBSNR across delays. Conclusions: These results highlight the effi cacy of wireless systems with HI adults. Speech-intelligibility benefi ts are affected by transmission delays only when the delay is greater than 40 ms and the coupling is vented.