Electrical hearing by cochlear implants (CIs) may be fundamentally different from the acoustic hearing by normal-hearing (NH) listeners, presumably showing unequal speech quality perception in various noise environments. Noise reduction (NR) algorithms used in CIs reduce the noise in favor of signal-to-noise ratio (SNR), regardless of plausible accompanying distortions that may degrade the speech quality perception. To gain a better understanding of CI speech quality perception, the present work aimed at investigating speech quality perception in diverse noise conditions, including factors of speech/noise levels, type of noise, and distortions caused by NR models. Fifteen NH and seven CI subjects participated in this study. Speech sentences were set to two different levels (65 and 75 dB SPL (Sound Pressure Level)). Two types of noise (Cafeteria and Babble) at three levels (55, 65, and 75 dB SPL) were used. Sentences were processed using two NR algorithms to investigate the perceptual sensitivity of CI and NH listeners to the distortion. All sentences processed with the combinations of these sets were presented to CI and NH listeners, and they were asked to rate the sound quality of speech as they perceived. The effect of each factor on the perceived speech quality was investigated based on the group-averaged quality rated by CI and NH listeners. Consistent with previous studies, CI listeners were not as sensitive as NH listeners to the distortion made by NR algorithms. Statistical analysis showed that the speech level has a significant effect on quality perception. At the same SNR, the quality of 65 dB speech was rated higher than that of 75 dB for CI users, but vice versa for NH listeners. Therefore, the present study showed that the perceived speech quality patterns were different between CI and NH listeners in terms of their sensitivity to distortion and speech level in a complex listening environment.

人工耳蜗 (CI) 的电听觉可能与正常听力 (NH) 听众的听觉有根本的不同，可能在各种噪声环境中表现出不同的语音质量感知。CI 中使用的降噪 (NR) 算法会降低噪声以提高信噪比 (SNR)，而不管可能会降低语音质量感知的合理伴随失真。为了更好地理解 CI 语音质量感知，目前的工作旨在研究不同噪声条件下的语音质量感知，包括语音/噪声水平、噪声类型和由 NR 模型引起的失真的因素。15 名 NH 和 7 名 CI 受试者参与了这项研究。语音句子被设置为两个不同的级别（65 和 75 dB SPL（声压级））。使用了三个级别（55、65 和 75 dB SPL）的两种类型的噪音（Cafeteria 和 Babble）。句子使用两种 NR 算法进行处理，以研究 CI 和 NH 听众对失真的感知敏感性。用这些集合的组合处理的所有句子都被呈现给 CI 和 NH 听众，他们被要求对他们感知的语音音质进行评分。基于 CI 和 NH 听众评定的组平均质量，研究了每个因素对感知语音质量的影响。与之前的研究一致，CI 听众不像 NH 听众那样对 NR 算法造成的失真敏感。统计分析表明，语音水平对质量感知有显着影响。在相同的信噪比下，CI 用户对 65 dB 语音质量的评价高于 75 dB，但对于 NH 听众而言，反之亦然。因此，本研究表明，在复杂的聆听环境中，CI 和 NH 听众的感知语音质量模式在对失真和语音电平的敏感性方面有所不同。