Resonant modes in transiently evoked otoacoustic emissions and asymmetries between left and right ear

A number of single-frequency resonant modes in click evoked otoacoustic emissions (OAEs) was investigated. The OAE modes were identified by means of an adaptive approximation method based on the matching pursuit (MP) algorithm. The signals were decomposed into basic waveforms coming from a very large and redundant dictionary of Gabor functions. The study was performed on transiently evoked otoacoustic emissions (TEOAEs) from left and right ears of 108 subjects. The correspondence between waveforms found by the procedure and resonant modes was shown (both for simulated noisy data and for single-person TEOAEs). The decomposition of TEOAEs made distinction between short and long-lasting components possible. The number of main resonant modes was studied by means of different criteria and they all led to similar results, indicating that the main features of the signal are explained on average by 10 waveforms. The same number of resonant modes for the right ear accounted for more energy than for the left ear.