包络调制率和载波频率对听觉时间调制检测能力的影响

通过心理物理实验探讨了包络调制率(<300 Hz)和纯音载波频率(<8 kHz)对听觉时间调制检测能力的影响. 测试信号为以纯音为载波的正弦幅度调制信号, 采用二选一强迫选择法和自适应调整步长的心理物理实验方法, 测试得到不同载波频率条件下的时间调制传递函数. 实验结果表明, 包络调制率和载波频率均会对听觉的时间调制检测能力产生影响. 当载波频率低于2 kHz时, 人耳的检测能力与调制率呈单调递增趋势;当载波频率高于3.5 kHz时, 检测能力也会受到调制率的显著影响, 但没有显著的单调变化趋势. 当调制率在10-100 Hz之间时, 检测能力不随载波频率明显变化;当调制率在150-300 Hz之间时, 调制检测能力随着载波频率上升而下降, 在载波频率达到3.5 kHz时, 调制检测能力不随载波频率显著改变.

Effects of envelope modulation rate and carrier frequency on auditory temporal modulation detection

The effects of envelope modulation rate (below 300 Hz) and pure-tone carrier frequency (below 8 kHz) on auditory temporal modulation detection ability (TMDA) are investigated through psychophysical experiments. The stimuli are sinusoidal amplitude-modulated signals with pure tone carriers. Two-alternative-forced-choice procedure with adaptive step is used. The temporal modulation transfer functions with different carrier frequencies are measured. Twenty-two normal-hearing subjects (22 to 29 years old) are recruited for this study. Experimental results show that both envelope modulation rate and carrier frequency have significant effects on TMDA. When carrier frequency is below 2 kHz, TMDA improves with the increase of modulation rate. When carrier frequency is above about 3.5 kHz, TMDA is influenced by the variation of carrier frequency, but without significant monotonic trend. When modulation rate is between 10 and 100 Hz, carrier frequency does not affect TMDA. When the modulation rate is between 150 and 300 Hz, TMDA decreases with the increase of carrier frequency until the carrier frequency is above 3.5 kHz.