Lj. Stover et al., LATENCY AND MULTIPLE SOURCES OF DISTORTION-PRODUCT OTOACOUSTIC EMISSIONS, The Journal of the Acoustical Society of America, 99(2), 1996, pp. 1016-1024
A novel analysis approach has been developed to examine the latency of
distortion product otoacoustic emissions (DPOAEs). DPOAEs were measur
ed in ten normal-hearing adults in a paradigm in which f(2) was held c
onstant and f(1) was varied. This paradigm was used with a wide range
of primary levels. Latency was estimated in two ways. In the first, a
phase-slope delay measurement was used which showed a significant resp
onse latency increase as stimulus intensity was decreased. In the seco
nd approach, an inverse-FFT procedure was used to provide a temporal a
nalysis of the data. Results of this analysis reveal a complex latency
structure with multiple peaks in the envelope of the time waveform. T
he latencies of individual peaks remain constant across level, however
short latency peaks have the greatest amplitudes at higher levels, an
d longer latency peaks are largest at low levels. These results would
be consistent with the idea that there are multiple intracochlear sour
ces for distortion product generation; however, a simple model, in whi
ch generation is assigned to the f(2) and the 2f(1)-f(2) place, does n
ot adequately explain the number of envelope peaks that were present i
n many ears. (C) 1996 Acoustical Society of America.