Johannesen Peter T, Lopez-Poveda Enrique A
Unidad de Audicion Computacional y Psicoacustica, Instituto de Neurociencias de Castilla y Leon, Universidad de Salamanca, 37007 Salamanca, Spain.
J Acoust Soc Am. 2008 Oct;124(4):2149-63. doi: 10.1121/1.2968692.
The aim was to investigate the correlation between compression exponent, compression threshold, and cochlear gain for normal-hearing subjects as inferred from temporal masking curves (TMCs) and distortion-product otoacoustic emission (DPOAEs) input-output (I/O) curves. Care was given to reduce the influence of DPOAE fine structure on the DPOAE I/O curves. A high correlation between compression exponent estimates obtained with the two methods was found at 4 kHz but not at 0.5 and 1 kHz. One reason is that the DPOAE I/O curves show plateaus or notches that result in unexpectedly high compression estimates. Moderately high correlation was found between compression threshold estimates obtained with the two methods, although DPOAE-based values were around 7 dB lower than those based on TMCs. Both methods show that compression exponent and threshold are approximately constant across the frequency range from 0.5 to 4 kHz. Cochlear gain as estimated from TMCs was found to be approximately 16 dB greater at 4 than at 0.5 kHz. In conclusion, DPOAEs and TMCs may be used interchangeably to infer precise individual nonlinear cochlear characteristics at 4 kHz, but it remains unclear that the same applies to lower frequencies.
目的是根据时间掩蔽曲线（TMC）和畸变产物耳声发射（DPOAE）输入-输出（I/O）曲线，研究正常听力受试者的压缩指数、压缩阈值与耳蜗增益之间的相关性。研究过程中注意减少DPOAE精细结构对DPOAE I/O曲线的影响。发现两种方法获得的4 kHz压缩指数估计值之间具有高度相关性，但在0.5 kHz和1 kHz时并非如此。一个原因是DPOAE I/O曲线显示出平台或凹陷，导致压缩估计值意外偏高。两种方法获得的压缩阈值估计值之间存在中度高度相关性，尽管基于DPOAE的值比基于TMC的值低约7 dB。两种方法均表明，在0.5至4 kHz的频率范围内，压缩指数和阈值大致恒定。从TMC估计的耳蜗增益在4 kHz时比在0.5 kHz时大约高16 dB。总之，DPOAE和TMC可互换使用，以推断4 kHz时精确的个体非线性耳蜗特征，但低频时是否同样适用仍不清楚。
