On the upper cutoff frequency of the auditory critical-band envelope detectors in the context of speech perception
On the upper cutoff frequency of the auditory critical-band envelope detectors in the context of speech perception
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DOI：
10.1121/1.1396325
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发表时间：
2001-09-01
影响因子：
2.4
通讯作者：
Ghitza, O
中科院分区：
文献类型：
--
作者：
Ghitza, O
神经生理学和心理物理学的研究为听觉系统中存在时间整合机制提供了证据。这些听觉机制可以被视为“探测器”，由其截止频率参数化。有兴趣在量化这些截止频率的直接心理物理测量，特别是与语音感知的任务，在这项研究中，固有的困难，在合成语音信号与规定的时间包络带宽在输出的听众耳蜗已被确定。为了规避这些困难。提出了一种具有交错临界频带包络的两分合成技术。该技术能够产生产生具有规定带宽的耳蜗时间包络的信号。此外，对于未平滑的包络，合成信号在感知上与原始信号无法区分。建立了这种技术，心理物理学实验已经进行了量化的听觉临界带包络检测器在阈值上的截止频率，使用高质量，宽带语音信号（带宽为7 kHz）作为测试刺激。这些实验表明为了保持语音质量（即，对于听不见的失真），给定听觉通道的包络信息的最小带宽显著小于临界频带带宽（大约是一个临界频带的一半）。在使用二分合成技术测量与具有良好质量水平的语音信号的可懂度相关的截止频率时遇到的困难（例如，以上MOS级3）也进行了讨论。(C)2001年，美国声学学会。
Studies in neurophysiology and in psychophysics provide evidence for the existence of temporal integration mechanisms in the auditory system. These auditory mechanisms may be viewed as "detectors," parametrized by their cutoff frequencies. There is an interest in quantifying those cutoff frequencies by direct psychophysical measurement, in particular for tasks that are related to speech perception, In this study, the inherent difficulties in synthesizing speech signals with prescribed temporal envelope bandwidth at the output of the listener cochlea have been identified. In order to circumvent these difficulties. a dichotic synthesis technique is suggested with interleaving critical-band envelopes. This technique is capable of producing signals which generate cochlear temporal envelopes with prescribed bandwidth. Moreover, for unsmoothed envelopes, the synthetic signal is perceptually indistinguishable from the original. With this technique established, psychophysical experiments have been conducted to quantify the upper cutoff frequency of the auditory critical-band envelope detectors at threshold, using high-quality, wideband speech signals (bandwidth of 7 kHz) as test stimuli. These experiments show that in order to preserve speech quality (i.e., for inaudible distortions), the minimum bandwidth of the envelope information for a given auditory channel is considerably smaller than a critical-band bandwidth (roughly one-half of one critical band). Difficulties encountered in using the dichotic synthesis technique to measure the cutoff frequencies relevant to intelligibility of speech signals with fair quality levels (e.g., above MOS level 3) are also discussed. (C) 2001 Acoustical Society of America.