双耳时间差变化感知阈限与时间差和频率的关系

Relative contribution of frequency and time difference to selectivity for interaural time difference

为探索双耳时间差(Interaural Time Difference,ITD)的感知机理,研究ITD恰可感知差异(Just Notice Difference,JND)与时间差和频率的关系。依据人耳对ITD的敏感程度的定性分析,非均匀地选取7个离散的ITD测试值,按照临界频带的划分方法将低频段划分为12个频带进行测试;采用1 up/2 down和2AFC心理学测试方法,同时采用窄带的高斯白噪声作为测试序列以避免相位混淆。测试结果表明:随频率的变化ITD的JND变化较为显著,在500 Hz左右出现极小值,两端较大;随ITD的增大,ITD的JND也相应增大。实验所得数据及结论可为多声道音频的高效压缩提供基础数据和理论支撑。

It is a significant way to explore the perceptual mechanism of Interaural Time Difference（ITD） by discovering the relative contribution of frequency and time difference to selectivity for ITD.Seven values of ITD is selected discretely and inhomogeneous in accordance with qualitative analysis of perceptual characteristics for ITD：0 μs,40 μs,100 μs,200 μs,350 μs,500 μs and 700 μs.The section of low frequency is divided into 12 sub-bands based on the division method of critical band.A self-adaption test method contained the traditional test methods such as 1 up/2 down and2 AFC is taken.The test sequences are chosen as narrowband Gaussian white noise in order to avoid phase aliasing.The experiment results demonstrate that：ITD threshold changes more significantly with frequency,and the minimum value occurs at about 500 Hz while the maximum values correspond to both side bands and the threshold increases as the ITD of the standard increasing.