van Veen T M, Houtgast T
J Acoust Soc Am. 1985 Feb;77(2):628-34. doi: 10.1121/1.391880.
The effect of sharpening or smoothing the spectral envelopes of synthetic vowel-like sounds on the dissimilarities perceived among these sounds was investigated by means of triadic comparisons. When a spectral envelope (dB on a log-frequency scale) is considered the sum of a series of sinusoidal spectral modulations (or ripples) of different densities (the ripple spectrum), spectral sharpening or smoothing can be described as an amplification or attenuation of a part of the original ripple spectrum. For a set of nine sounds comprising different degrees of spectral sharpening of a single vowel, the perceived dissimilarities were found to be dominated by a specific part of the ripple spectrum, i.e., by spectral modulations with a density of about 2 ripples/oct. The possible role of lateral suppression in relation to this dominant region is discussed. For a set of 18 sounds comprising six vowels, each in three different versions (sharpened, normal, or smoothed), the dissimilarities were found to be determined mainly by the global shape of the spectral envelopes, i.e., by spectral modulations up to about 1.5-2 ripples/oct. Details of the spectral envelope (including the region of 2 ripples/oct where lateral suppression is effective) appear to be of minor influence on vowel dissimilarities.
通过三元比较研究了对类似元音的合成声音的频谱包络进行锐化或平滑处理对这些声音之间感知到的差异的影响。当将频谱包络（对数频率标度上的分贝）视为不同密度的一系列正弦频谱调制（或波纹）（波纹频谱）的总和时，频谱锐化或平滑可以描述为原始波纹频谱一部分的放大或衰减。对于一组包含单个元音不同程度频谱锐化的九个声音，发现感知到的差异主要由波纹频谱的特定部分主导，即由密度约为2波纹/倍频程的频谱调制主导。讨论了侧抑制相对于该主导区域的可能作用。对于一组包含六个元音的18个声音，每个元音有三种不同版本（锐化、正常或平滑），发现差异主要由频谱包络的整体形状决定，即由高达约1.5 - 2波纹/倍频程的频谱调制决定。频谱包络的细节（包括侧抑制有效的2波纹/倍频程区域）似乎对元音差异影响较小。
