Kohlrausch A, Sander A
Institute for Perception Research (IPO), Eindhoven, The Netherlands.
J Acoust Soc Am. 1995 Mar;97(3):1817-29. doi: 10.1121/1.413097.
This article investigates how the amplitude and phase characteristics of the inner ear influence the spectrotemporal representation of harmonic complex sounds. Five experiments are reported, in each of which three sets of maskers are compared that differ only in their phase spectra. The amplitude spectra of the complexes were flat and the phase choices were (a) zero phase, (b) Schroeder phases with a positive sign, and (c) Schroeder phases with a negative sign. In the first four experiments, the spectra contained all harmonics between 200 and 2000 Hz. In experiments 1 and 2, the signal frequency was fixed at 1100 Hz and the fundamental frequency of the maskers was varied. In experiments 3 and 4, the fundamental frequency of the maskers was fixed and the signal frequency varied between 200 and 2000 Hz. In experiments 1 and 3, the signal duration was long compared to the period of the maskers. In experiments 2 and 4, the signal duration was only 5 ms and thresholds were determined for different time points within the masker's period. The results show a strong correlation between the minima of the short signal's thresholds and the threshold of the long signal. In experiment 5, the spectral extent of the masker was shifted to values one octave lower (100 to 1000 Hz) or one or two octaves higher (400 to 4000 Hz and 800 to 8000 Hz, respectively). For each spectral region, masked thresholds of a long signal were obtained for three values of the fundamental frequency. In all five experiments the thresholds depended very much on the specific phase choices with differences of up to 25 dB. The masker with a negative Schroeder phase always led to the highest thresholds. The thresholds of the masker with a positive Schroeder phase, on the other hand, were for a wide range of parameters lower than the thresholds for the zero-phase masker. These phase effects are most likely caused by the phase characteristic of the basilar-membrane filter, which affects the flat envelopes of the two Schroeder-phase maskers in a very different way. For an appropriate choice of parameters, one of the two becomes even more strongly modulated than the zero-phase complex. This latter observation imposes some restrictions on the second derivative (curvature) of the phase-versus-frequency relation for the auditory filters.
本文研究内耳的振幅和相位特性如何影响谐波复合声音的频谱时间表征。报告了五个实验，每个实验中比较了三组仅相位谱不同的掩蔽声。复合声的振幅谱是平坦的，相位选择为：(a) 零相位；(b) 带正号的施罗德相位；(c) 带负号的施罗德相位。在前四个实验中，频谱包含200至2000赫兹之间的所有谐波。在实验1和2中，信号频率固定在1100赫兹，掩蔽声的基频变化。在实验3和4中，掩蔽声的基频固定，信号频率在200至2000赫兹之间变化。在实验1和3中，与掩蔽声的周期相比，信号持续时间较长。在实验2和4中，信号持续时间仅为5毫秒，并确定了掩蔽声周期内不同时间点的阈值。结果表明，短信号阈值的最小值与长信号的阈值之间存在很强的相关性。在实验5中，掩蔽声的频谱范围移至低一个倍频程的值（100至1000赫兹）或高一个或两个倍频程的值（分别为400至4000赫兹和800至8000赫兹）。对于每个频谱区域，针对三个基频值获得了长信号的掩蔽阈值。在所有五个实验中，阈值很大程度上取决于特定的相位选择，差异高达25分贝。带负施罗德相位的掩蔽声总是导致最高的阈值。另一方面，带正施罗德相位的掩蔽声在很宽的参数范围内的阈值低于零相位掩蔽声的阈值。这些相位效应很可能是由基底膜滤波器的相位特性引起的，它以非常不同的方式影响两个施罗德相位掩蔽声的平坦包络。对于参数的适当选择，两者之一甚至比零相位复合声受到更强的调制。后一观察结果对听觉滤波器的相位与频率关系的二阶导数（曲率）施加了一些限制。
