van Dijk P, Wit H P
Department of Otorhinolaryngology, University Hospital Groningen, The Netherlands.
J Acoust Soc Am. 1998 Jul;104(1):336-43. doi: 10.1121/1.423259.
The frequency spectrum of a spontaneous otoacoustic emission (SOAE) recording may contain multiple narrow peaks. These peaks correspond to multiple SOAEs emitted by the inner ear. The individual SOAEs exhibit small amplitude fluctuations. The correlation between the amplitude fluctuations of multiple SOAEs in an individual ear was studied in 19 SOAE recordings from humans. For 424 pairs of SOAEs, the normalized amplitude cross-correlation function was computed. Significant correlation was found in 63 pairs (15%): 34 pairs showed positive and 29 pairs showed negative correlation. Some SOAE pairs were part of an equally spaced triplet of emission peaks, with one SOAE apparently generated as a distortion product of the other two "primary" SOAEs. The occurrence of correlation between a distortion product SOAE and a "primary" SOAE was 56%. This is significantly higher than the occurrence of correlation for the entire set of SOAE pairs. In addition, the spectral width of the distortion product SOAE was correlated with the spectral width of the "primary" SOAEs (R = 0.87, p < 10(-6)). For 79% of the correlated SOAE pairs, the cross-correlation function peaked at positive time delay. This indicates that for these pairs the fluctuation of the lower frequency emission lagged the fluctuation of the higher frequency emission. The average peak delay was 11.0 ms (s.d. 22.1 ms). The results demonstrate that interactions between SOAEs in an individual ear frequently occur and are asymmetrical.
自发性耳声发射（SOAE）记录的频谱可能包含多个窄峰。这些峰对应于内耳发出的多个SOAE。单个SOAE表现出小幅度波动。在来自人类的19份SOAE记录中研究了单耳中多个SOAE幅度波动之间的相关性。对于424对SOAE，计算了归一化幅度互相关函数。在63对（15%）中发现了显著相关性：34对呈正相关，29对呈负相关。一些SOAE对是等间距发射峰三联体的一部分，其中一个SOAE显然是另外两个“初级”SOAE的失真产物。失真产物SOAE与“初级”SOAE之间相关性的发生率为56%。这显著高于整个SOAE对集合中相关性的发生率。此外，失真产物SOAE的频谱宽度与“初级”SOAE的频谱宽度相关（R = 0.87，p < 10^(-6)）。对于79%的相关SOAE对，互相关函数在正时间延迟处达到峰值。这表明对于这些对，低频发射的波动滞后于高频发射的波动。平均峰值延迟为11.0毫秒（标准差22.1毫秒）。结果表明，单耳中SOAE之间的相互作用频繁发生且不对称。
