Department of Otolaryngology, Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Ministry of Education of China.
Department of Head and Neck Surgery, David Geffen School of Medicine, University of California.
Trends Hear. 2020 Jan-Dec;24:2331216520916106. doi: 10.1177/2331216520916106.
For normal-hearing (NH) listeners, monaural factors, such as voice pitch cues, may play an important role in the segregation of speech signals in multitalker environments. However, cochlear implant (CI) users experience difficulties in segregating speech signals in multitalker environments in part due to the coarse spectral resolution. The present study examined how the vocal characteristics of the target and masking talkers influence listeners’ ability to extract information from a target phrase in a multitalker environment. Speech recognition thresholds (SRTs) were measured with one, two, or four masker talkers for different combinations of target-masker vocal characteristics in 10 adult Mandarin-speaking NH listeners and 12 adult Mandarin-speaking CI users. The results showed that CI users performed significantly poorer than NH listeners in the presence of competing talkers. As the number of masker talkers increased, the mean SRTs significantly worsened from –22.0 dB to –5.2 dB for NH listeners but significantly improved from 5.9 dB to 2.8 dB for CI users. The results suggest that the flattened peaks and valleys with increased numbers of competing talkers may reduce NH listeners’ ability to use dips in the spectral and temporal envelopes that allow for “glimpses” of the target speech. However, the flattened temporal envelope of the resultant masker signals may be less disruptive to the amplitude contour of the target speech, which is important for Mandarin-speaking CI users’ lexical tone recognition. The amount of masking release was further estimated by comparing SRTs between the same-sex maskers and the different-sex maskers. There was a large amount of masking release in NH adults (12 dB) and a small but significant amount of masking release in CI adults (2 dB). These results suggest that adult CI users may significantly benefit from voice pitch differences between target and masker speech.
对于听力正常（NH）的听众来说，单声道因素，如语音音高线索，可能在多说话人环境中分离语音信号方面发挥重要作用。然而，由于频谱分辨率粗糙，人工耳蜗（CI）使用者在多说话人环境中分离语音信号存在困难。本研究考察了目标和掩蔽说话者的声音特征如何影响听众从多说话人环境中的目标短语中提取信息的能力。使用 10 名成年讲普通话的 NH 听众和 12 名成年讲普通话的 CI 用户，对不同目标-掩蔽说话者声音特征组合的情况下，使用一个、两个或四个掩蔽说话者测量语音识别阈值（SRT）。结果表明，在存在竞争说话者的情况下，CI 用户的表现明显逊于 NH 听众。随着掩蔽说话者数量的增加，NH 听众的平均 SRT 从-22.0dB 显著恶化到-5.2dB，而 CI 用户的 SRT 从 5.9dB 显著改善到 2.8dB。结果表明，随着竞争说话者数量的增加，频谱和时域包络中的峰和谷变得更加平坦，这可能会降低 NH 听众利用目标语音的“ glimpses”来识别语音的能力。然而，掩蔽信号的平坦时域包络可能对目标语音的幅度轮廓干扰较小，这对讲普通话的 CI 用户的音节识别很重要。通过比较同性别掩蔽者和不同性别掩蔽者之间的 SRT，进一步估计了掩蔽释放量。NH 成年人有大量的掩蔽释放（12dB），CI 成年人有少量但显著的掩蔽释放（2dB）。这些结果表明，成年 CI 用户可能会从目标和掩蔽语音之间的语音音高差异中显著受益。
