Majdak Piotr, Laback Bernhard
Acoustics Research Institute, Austrian Academy of Sciences, Vienna, Austria.
J Acoust Soc Am. 2009 Jun;125(6):3903-13. doi: 10.1121/1.3120413.
The effects of center frequency and pulse rate on the sensitivity to ongoing envelope interaural time differences (ITDs) were investigated using bandpass-filtered pulse trains. Three center frequencies (4.6, 6.5, and 9.2 kHz) were tested with bandwidths scaled to stimulate an approximately constant range on the basilar membrane. The pulse rate was varied from 200 to 588 pps (pulses per seconds). Five normal-hearing (NH) subjects were tested. Averaged over all rates, the results show a small decrease in sensitivity with increasing center frequency. For all center frequencies, sensitivity decreases with increasing pulse rate, yielding a rate limit of approximately 500 pps. The lack of an interaction between pulse rate and center frequency indicates that auditory filtering was not the rate limiting factor in ITD perception and suggests the existence of other limiting mechanisms, such as phase locking or more central processes. It is concluded that the comparison of the rate limits in ITD perception between cochlear-implant listeners and NH subjects listening to high-frequency bandpass-filtered pulse trains is not confounded by the choice of center frequency of stimulation in NH listeners.
使用带通滤波脉冲序列研究了中心频率和脉冲率对正在进行的包络双耳时间差（ITD）敏感性的影响。测试了三个中心频率（4.6、6.5和9.2千赫），其带宽按比例缩放，以刺激基底膜上大致恒定的范围。脉冲率在200至588次/秒（脉冲每秒）之间变化。测试了五名听力正常（NH）的受试者。在所有频率上进行平均，结果显示随着中心频率的增加，敏感性略有下降。对于所有中心频率，敏感性随着脉冲率的增加而降低，产生的频率限制约为500次/秒。脉冲率和中心频率之间缺乏相互作用表明，听觉滤波不是ITD感知中的频率限制因素，并提示存在其他限制机制，如相位锁定或更高级的中枢处理过程。得出的结论是，人工耳蜗植入者与聆听高频带通滤波脉冲序列的听力正常受试者之间在ITD感知中的频率限制比较，不会因听力正常受试者中刺激中心频率的选择而混淆。
