Microphone directionality improves speech perception in Mandarin-speaking cochlear implant users

Speech understanding in noise remains challenging for cochlear implant (CI) users. To address this, microphone directionality has been integrated into speech processors to improve the signal-to-noise ratio. Despite demonstrated benefits for users of non-tonal language, studies investigating its efficacy for users of tonal languages are limited.

In this study, we evaluated the benefit of microphone directionality in 24 Mandarin-speaking adult CI users with uni- or bilateral post-lingual deafness (≥ 6 months of experience) using the Mandarin Speech Test Materials in quiet and noise. Speech and noise were presented simultaneously (S0N180). Results of the MSTM are presented as speech recognition score (SRS) as percentage correct.

Performance with an omnidirectional speech processor (OPUS 2) was compared to one (SONNET) with three directional modes (omni, natural, adaptive). A visual analogue scale (VAS) questionnaire was used to assess preferences for each speech processor setting. Directional modes significantly improved speech perception in noise: SONNET/natural outperformed both OPUS 2 by 10.4% (95% CI: 3.4% to 17.5%; p = 0.006) and SONNET/omni by 12.4% (95% CI: 6.0% to 18.7%; p = 0.001), while SONNET/adaptive outperformed both OPUS 2 (by 13.6%; 95% CI: 7.9% to 19.3%; p < 0.001) and SONNET/omni (by 15.6%; 95% CI: 8.4% to 22.7%; p < 0.001).

The difference between SONNET/adaptive and SONNET/natural was 3.17% points (95% CI: -2.2% to 8.5%; p = 0.231). No significant difference was observed in quiet. 63% of participants favored SONNET/adaptive in noise. Under the S0N180 conditions tested, directional microphone settings were associated with better speech perception in noise than omnidirectional settings in Mandarin-speaking CI users, whereas no statistically significant difference was observed between the SONNET/adaptive and SONNET/natural settings.

Upgrading from an omnidirectional speech processor to one equipped with directional technology may provide substantial and clinically meaningful benefit. We gratefully acknowledge support from the China Scholarship Council (CSC) and sincerely thank all participants for their voluntary involvement, as well as Handi Liu and Ya’nan Lan for their contributions to the testing procedures. This work was supported by the Beijing Municipal Public Welfare Development and Reform Pilot Project for Medical Research Institutes, the Beijing Municipal Administration of Hospitals Incubating Program (PX2022006) and the Beijing Nova Program (20220484211).

Clinical Audiology Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China Beier Qi, Ruijuan Dong, Xin Gu, Bowen Zhuang & Shuo Wang Department of Otolaryngology-Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China Key Laboratory of Otolaryngology Head and Neck Surgery, Capital Medical University, Ministry of Education, Beijing, China Beijing Institute of Otolaryngology, Beijing, China The authors declare no competing interests. The study was reviewed and approved by the Research Ethics Committee of Beijing Tongren Hospital (No. trec2024-ky078). Informed consent was obtained from all subjects prior to participation in the study.