Otoacoustic emissions are signals emitted from the cochlea, either spontaneously or evoked by stimuli. Measured with an acoustic probe sealed in the ear-canal, they reveal information about a part of the mechanism of hearing that is otherwise inaccessible. Outer hair cells in the cochlea work to improve hearing sensitivity by means of nonlinear amplification, which produces distortion. In the measurement of otoacoustic emissions, two tones can be delivered to the cochlea to invoke this nonlinearity and elicit the distortion-product otoacoustic emission (DPOAE). DPOAEs arise mainly from two spatially separated generation mechanisms, thus making interpretation of DPOAE measurements complicated. In this study, we test whether or not source separation by group delays is equivalent to separation by time delays – either result is equally interesting to understand given the complexity of the cochlea. Specifically, DPOAEs from 500 Hz to 4000 Hz were measured in 20 normal-hearing human ears, using exponentially swept, fixed-ratio primaries. Source separation by group delays relied on gating in the DPOAE latency domain, obtained by an inverse Fourier transform of DPOAE magnitude and phase. Source separation by time delays relied on adding physical delays, suggested by the group delays, to a model used to estimate the swept DPOAEs.
|Konference||Joint Baltic-Nordic Acoustics Meeting 2012|
|Periode||18/06/2012 → 20/06/2012|
|Navn||Joint Baltic-Nordic Acoustics Meeting (BNAM), Proceedings|