Kewley-Port D, Zheng Y
Department of Speech and Hearing Sciences, Indiana University, Bloomington 47405, USA.
J Acoust Soc Am. 1998 Mar;103(3):1654-66. doi: 10.1121/1.421264.
Thresholds for formant discrimination of female and male vowels are significantly elevated by two stimulus factors, increases in formant frequency and fundamental frequency [Kewley-Port et al., J. Acoust. Soc. Am. 100, 2462-2470 (1996)]. The present analysis systematically examined whether auditory models of vowel sounds, including excitation patterns, specific loudness, and a Gammatone filterbank, could explain the effects of stimulus parameters on formant thresholds. The goal was to determine if an auditory metric could be specified that reduced variability observed in the thresholds to a single-valued function across four sets of female and male vowels. Based on Sommers and Kewley-Port [J. Acoust. Soc. Am. 99, 3770-3781 (1996)], four critical bands around the test formant were selected to calculate a metric derived from excitation patterns. A metric derived from specific loudness difference (delta Sone) was calculated across the entire frequency region. Since analyses of spectra from Gammatone filters gave similar results to those derived from excitation patterns, only the 4-ERB (equivalent rectangular bandwidth) and delta Sone metrics were analyzed in detail. Three criteria were applied to the two auditory metrics to determine if they were single-valued functions relative to formant thresholds for female and male vowels. Both the 4-ERB and delta Sone metrics met the criteria of reduced slope, reduced effect of fundamental frequency, although delta Sone was superior to 4-ERB in reducing overall variability. Results suggest that the auditory system has an inherent nonlinear transformation in which differences in vowel discrimination thresholds are almost constant in the internal representation.
两个刺激因素，即共振峰频率和基频的增加，会显著提高女性和男性元音共振峰辨别阈值[凯维 - 波特等人，《美国声学学会杂志》100, 2462 - 2470 (1996)]。本分析系统地研究了元音声音的听觉模型，包括激励模式、特定响度和伽马通滤波器组，是否能够解释刺激参数对共振峰阈值的影响。目标是确定是否可以指定一种听觉度量，将在阈值中观察到的变异性降低到跨越四组女性和男性元音的单值函数。基于萨默斯和凯维 - 波特[《美国声学学会杂志》99, 3770 - 3781 (1996)]，选择测试共振峰周围的四个临界频带，以计算从激励模式导出的度量。在整个频率区域计算从特定响度差异（增量宋）导出的度量。由于对伽马通滤波器频谱的分析给出了与从激励模式导出的结果相似的结果，因此仅详细分析了4 - ERB（等效矩形带宽）和增量宋度量。将三个标准应用于这两个听觉度量，以确定它们相对于女性和男性元音共振峰阈值是否为单值函数。4 - ERB和增量宋度量都满足斜率降低、基频影响降低的标准，尽管增量宋在降低总体变异性方面优于4 - ERB。结果表明，听觉系统具有固有的非线性变换，其中元音辨别阈值的差异在内部表示中几乎是恒定的。
