Effects of the number of channels and speech-to-noise ratio on rate of connected discourse tracking through a simulated cochlear implant speech processor
Effects of the number of channels and speech-to-noise ratio on rate of connected discourse tracking through a simulated cochlear implant speech processor
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DOI：
10.1097/00003446-200110000-00007
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发表时间：
2001-10-01
期刊：
影响因子：
3.7
通讯作者：
Wilkinson, L
中科院分区：
文献类型：
--
作者：
Faulkner, A;Rosen, S;Wilkinson, L
目的：通过人工耳蜗语音处理的仿真研究，探讨通道数和语音噪声比对连接语篇跟踪（CDT）的影响。以往的研究都是使用引文形式的元音和辅音材料或简单的句子。CDT率预计将不太可能受到限制的天花板效应和日常语音communication.Design的代表：四个正常听力的受试者提出了通过实时正弦激励声码器有三个，四个，八个，或12个通道的语音处理。从放置在每个频带中心频率处的每个频带调制的正弦载波信号提取的幅度包络。在声码器处理之前，根据实时测量的语音电平，在三个信噪比下对语音进行频谱整形噪声（+7，+12，+17 dB）。结果：CDT率在安静和噪声中均随通道数增加至8而显著增加，并且随噪声水平从安静增加而显著降低。通道数量和语音噪声比对CDT率的影响与噪声测试（HINT）句子、辅音和元音的可懂度测量高度相关。然而，即使在噪声中，HINT句子分数也显示出天花板效应，这掩盖了具有八个或更多通道的处理器的优势。中等水平的噪音，只有轻微的影响，其他措施显着影响CDT率。CDT率与三个或四个波段的光谱信息远低于渐近率，特别是在存在噪声的情况下。
Objective: To investigate the effects of number of channels and speech-to-noise ratio on connected discourse tracking (CDT) through simulations of cochlear implant speech processing. Previous studies have used citation-form vowel and consonant materials or simple sentences. CDT rates were expected to be less likely to be limited by ceiling effects and more representative of everyday speech communication.Design: Four normal-hearing subjects were presented with speech processed through a real-time sine-excited vocoder having three, four, eight, or 12 channels. Amplitude envelopes extracted from each band modulated sinusoidal carrier signals placed at each band center frequency. Speech-spectrum shaped noise was added to speech before vocoder processing at three signal to noise ratios based on real-time measurements of speech level (+7, +12, +17 dB).Results: CDT rates increased significantly with number of channels up to eight in both quiet and noise, and decreased significantly with each increase in noise level from quiet.Conclusions: The effects on CDT rates of the number of channels and speech-to-noise ratio are highly correlated with intelligibility measures for Hearing in Noise Test (HINT) sentences, consonants and vowels. However, HINT sentence scores even in noise show ceiling effects that obscure the advantages of processors with eight or more channels. Moderate levels of noise that have only slight effects on other measures significantly affected CDT rate. CDT rates with three or four bands of spectral information were much lower than asymptotic rates, especially in the presence of noise.