All India Institute of Speech and Hearing, Manasagangothri, Mysore 570006, India.
J Acoust Soc Am. 2010 Feb;127(2):660-3. doi: 10.1121/1.3277218.
A single subject whose audiogram resembled an inverted V shape (good hearing at 4000 Hz, and poorer hearing at other frequencies was tested. Results of the threshold-equalizing noise test suggested that a dead region (DR) in the cochlea was present at all test frequencies from 500 to 3000 Hz, but no DR was present at 4000 Hz. Psychophysical tuning curves (PTCs) obtained using signal frequencies of 2000, 3000, 4000, and 6000 Hz showed upward shifted tips for the lowest two signal frequencies, and a downward shifted tip for the highest frequency. The results of the PTCs suggested a functioning region extending from 3900 to 5100 Hz, with DRs outside that range. The identification of nonsense syllables, amplified according to the "Cambridge formula," was measured as a function of lowpass or highpass filter cutoff frequency. The results suggested that useful speech information could only be extracted from a limited frequency range around 4000 Hz.
一位听力图呈倒 V 形的受试者（4000Hz 听力较好，其他频率听力较差）接受了测试。阈移噪声测试的结果表明，在 500 至 3000Hz 的所有测试频率中，耳蜗内都存在一个死区（DR），但在 4000Hz 时不存在 DR。使用 2000、3000、4000 和 6000Hz 的信号频率获得的心理调谐曲线（PTCs）显示，最低两个信号频率的尖端向上移动，而最高频率的尖端向下移动。PTCs 的结果表明，在该范围内存在一个从 3900 到 5100Hz 的功能区，其外存在 DR。根据“剑桥公式”放大的无意义音节的识别被测量为低通或高通滤波器截止频率的函数。结果表明，有用的语音信息只能从大约 4000Hz 的有限频率范围内提取。
