Abstract
The amplitudes of distortion-product otoacoustic emissions (DPOAEs) may abruptly decrease even though the stimulus level is relatively high. These notches observed in the DPOAE input/output functions or distortion-product grams have been hypothesized to be due to destructive interference between wavelets generated by distributed sources of the nonlinear-distortion component of DPOAEs. In this paper, simulations with a smooth cochlear model and its analytical solution support the hypothesis that destructive interference between individual wavelets may lead to the amplitude notches and explain the cause for onset and offset amplitude overshoots in the DPOAE signal measured for intensity pairs in the notches.
Highlights
Distortion-products (DPs) generated in the cochlea may be recorded by a microphone placed in the ear canal
Simulations with a smooth cochlear model and its analytical solution support the hypothesis that destructive interference between individual wavelets may lead to the amplitude notches and explain the cause for onset and offset amplitude overshoots in the distortion-product otoacoustic emissions (DPOAEs) signal measured for intensity pairs in the notches
Theoretical tools presented in Vencovsky et al (2019) are used in this paper to study the primary source at large stimulus levels (>60 dB sound pressure level (SPL)) and with a frequency ratio between the stimuli of f2/f1 1⁄4 1.2, which is near the “optimal” ratio for which experiments have shown an abrupt decrease of DPOAE amplitude (e.g., Johannesen and Lopez-Poveda, 2010; Martin et al, 2013; Whitehead et al, 1992)
Summary
Distortion-products (DPs) generated in the cochlea may be recorded by a microphone placed in the ear canal. DPs evoked by two pure tones of nearby frequencies are called distortion-product otoacoustic emissions (DPOAEs) (Probst et al, 1991). Theoretical tools presented in Vencovsky et al (2019) are used in this paper to study the primary source at large stimulus levels (>60 dB SPL) and with a frequency ratio between the stimuli of f2/f1 1⁄4 1.2, which is near the “optimal” ratio for which experiments have shown an abrupt decrease of DPOAE amplitude (e.g., Johannesen and Lopez-Poveda, 2010; Martin et al, 2013; Whitehead et al, 1992). A possible explanation for the pronounced notches in the DPOAE amplitude is destructive interference between the primary sources (Martin et al, 1999, 2003, 2013). Since the analytical solution of the cochlear model presented in Vetesnık and Gummer (2012) and Vencovsky et al (2019)
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