Effects of noise on integration of acoustic and electric hearing within and across ears.

In bimodal listening, cochlear implant (CI) users combine electric hearing (EH) in one ear and acoustic hearing (AH) in the other ear. In electric-acoustic stimulation (EAS), CI users combine EH and AH in the same ear. In quiet, integration of EH and AH has been shown to be better with EAS, but with greater sensitivity to tonotopic mismatch in EH. The goal of the present study was to evaluate how external noise might affect integration of AH and EH within or across ears. Recognition of monosyllabic words was measured for normal-hearing subjects listening to simulations of unimodal (AH or EH alone), EAS, and bimodal listening in quiet and in speech-shaped steady noise (10 dB, 0 dB signal-to-noise ratio). The input/output frequency range for AH was 0.1–0.6 kHz. EH was simulated using an 8-channel noise vocoder. The output frequency range was 1.2–8.0 kHz to simulate a shallow insertion depth. The input frequency range was either matched (1.2–8.0 kHz) or mismatched (0.6–8.0 kHz) to the output frequency range; the mismatched input range maximized the amount of speech information, while the matched input resulted in some speech information loss. In quiet, tonotopic mismatch differently affected EAS and bimodal performance. In noise, EAS and bimodal performance was similarly affected by tonotopic mismatch. The data suggest that tonotopic mismatch may differently affect integration of EH and AH in quiet and in noise.

在双模聆听中，人工耳蜗（CI）使用者一只耳朵结合电听觉（EH），另一只耳朵结合声学听觉（AH）。在电 - 声刺激（EAS）中，CI使用者在同一只耳朵中结合EH和AH。在安静环境下，已表明EAS对EH和AH的整合效果更好，但对EH中的音调拓扑失配更为敏感。本研究的目的是评估外部噪声如何影响同耳或双耳内AH和EH的整合。对听力正常的受试者在安静环境以及语音形状的稳态噪声（10分贝、0分贝信噪比）下，对单音节词的识别进行了测量，这些受试者聆听单模（仅AH或仅EH）、EAS和双模聆听的模拟声音。AH的输入/输出频率范围是0.1 - 0.6千赫兹。使用8通道噪声声码器模拟EH。输出频率范围是1.2 - 8.0千赫兹以模拟浅插入深度。输入频率范围与输出频率范围要么匹配（1.2 - 8.0千赫兹），要么失配（0.6 - 8.0千赫兹）；失配的输入范围使语音信息量最大化，而匹配的输入会导致一些语音信息丢失。在安静环境下，音调拓扑失配对EAS和双模性能的影响不同。在噪声环境下，音调拓扑失配对EAS和双模性能的影响相似。数据表明，音调拓扑失配在安静环境和噪声环境下对EH和AH整合的影响可能不同。