Impact of noise modulation characteristics on speech perception in cochlear implant users

Introduction:

Subjects with normal hearing typically show improved speech perception in noise with temporal gaps, whereas cochlear implant (CI) users oftentimes do not benefit or even degrade in such conditions. The aim of the present study was to compare the impact of temporal modulation on speech perception in noise

Material and methods:

14 subjects with normal hearing (NH) and 12 bilateral CI users aged between 18 and 45 years took part in the study. The speech reception threshold (SRT) in noise was assessed adaptively using the German matrix test (OLSA). Noise stimuli were the unmodulated Olnoise and three noise types with identical spectrum to Olnoise but different temporal modulation characteristics. Additionally, the ISTS noise and Japanese speech (JS) were used.

Results:

The NH group achieved up to 17 dB better SRTs in the modulated Olnoise compared with the unmodulated condition. CI users showed 4.5 dB higher (i.e. worse) SRTs than the NH group. Mean SRTs in modulated noises were 2.2 dB better than in Olnoise, whereas higher SRTs were found in ISTS (2.2 dB higher) and JS (4.6 dB higher). The NH group had 17 – 18 dB lower SRTs in ISTS and JS noise compared with the CI group.

Conclusion:

Results of the present study showed a small effect of gap listening in CI users in the presence of modulated non-natural stimuli. Differently than in NH subjects, SRTs in the presence of natural or speech-like noise stimuli significantly deteriorated compared with the unmodulated condition.

Publication History

Publication Date:
23 April 2019 (online)