Effect of microphone directionality setting on speech recognition in noise in bilateral CI users

Introduction Directional microphones improve speech recognition for frontal speech in noise in CI users. For speaker positions at the side, application of microphones with less focused directionality might be beneficial. This study aims to assess the effect of microphone directionality setting used with 2 sound processors CP1000 on speech understanding in noise in bilateral CI (BiCI) users.

Material and methods 11 BiCI users were included. Speech understanding was assessed as speech reception threshold (SRT) in 2 different noises, ICRA5-250 (ICRA), and road traffic noise (TRAFF). Speech and noise were presented in 4 configurations using 4 speakers: speech from front, left, right or behind, and noise from the 3 remaining speakers. With regard to the sides of the 1st and 2nd CI, the configurations are referred to as S0N3, Sci1N3, S180N3, and Sci2N3. The SRT was assessed for application of 4 microphone directionality settings: moderate directional microphone (Standard) with both CI (Std/Std), directional microphone Zoom with both CI (Zoom/Zoom), Standard with 1st CI and Zoom with 2nd CI (1Std/2Zoom), and Zoom with 1st CI and Standard with 2nd CI (1Zoom/2Std).

Results In S0N3, the BiCI users showed lowest SRT in ICRA for Zoom/Zoom, and largest SRT for Std/Std. In Sci1N3, SRTs in both noises were lower with 1Std/2Zoom and Std/Std compared to 1Zoom/2Std and Zoom/Zoom. In Sci2N3, BiCI users yielded lower SRTs in both noises with 1Zoom/2Std and Std/Std compared to 1Std/2Zoom and Zoom/Zoom.

Conclusion For presentation of speech from the side, using Standard with the CI at the speech side and Standard or Zoom with the contralateral CI enables better speech in noise performance compared to Zoom with the CI at the speech side and Standard or Zoom with the contralateral CI.

Publication History

Article published online:
19 April 2024