Speech recognition by bilateral cochlear implant users in a cocktail-party setting

TLDR

Previous studies on bilateral cochlear implant users examined only a single interferer; this study investigates more realistic cocktail‑party scenarios with multiple interferers, sometimes from both sides. The authors measured speech reception thresholds in bilateral cochlear implant users under unilateral and bilateral listening across four spatial configurations with one or three interferers (modulated noise or competing talkers), then analyzed binaural benefits such as monaural advantage and binaural interaction. Bilateral users achieved a 2–5 dB overall spatial release, mainly from a 1–6 dB monaural advantage that was greatest with energetic interferers; no binaural interaction benefit was observed, and performance with speech interferers was markedly poorer than with noise, indicating limited use of binaural cues under informational masking and that noise‑based tests underestimate real‑world challenges.

Abstract

Unlike prior studies with bilateral cochlear implant users which considered only one interferer, the present study considered realistic listening situations wherein multiple interferers were present and in some cases originating from both hemifields. Speech reception thresholds were measured in bilateral users unilaterally and bilaterally in four different spatial configurations, with one and three interferers consisting of modulated noise or competing talkers. The data were analyzed in terms of binaural benefits including monaural advantage (better-ear listening) and binaural interaction. The total advantage (overall spatial release) received was 2–5dB and was maintained with multiple interferers present. This advantage was dominated by the monaural advantage, which ranged from 1to6dB and was largest when the interferers were mostly energetic. No binaural-interaction benefit was found in the present study with either type of interferer (speech or noise). While the total and monaural advantage obtained for noise interferers was comparable to that attained by normal-hearing listeners, it was considerably lower for speech interferers. This suggests that bilateral users are less capable of taking advantage of binaural cues, in particular, under conditions of informational masking. Furthermore, the use of noise interferers does not adequately reflect the difficulties experienced by bilateral users in real-life situations.