Noise suppression of transient-evoked otoacoustic emissions. I. A comparison with the non-linear method

A new method to record transient-evoked otoacoustic emissions (TEOAEs) is introduced. Click stimuli were presented both with and without a simultaneously presented wide-band noise burst. Subtraction of the recorded signal evoked by the noise burst plus click from the signal evoked by the click alone, cancelled the eardrum reflection components of the response and resulted in a measure of the emission. This was used to obtain the TEOAEs from 21 subjects for peak click stimulus levels of 48-66 dB SPL. The root-mean-square (RMS) level of the noise burst was set 10 dB higher than the peak click level, and resulted in suppression of the TEOAE by up to 20 dB. The TEOAE waveforms obtained by the new method were compared to those obtained with Kemp's non-linear method, and were indistinguishable in 20 of the 21 subjects. On basis of the emission spectra, they were indistinguishable in 18 out of 21 subjects. The latencies of narrow-band filtered components from the TEOAEs obtained with the two methods were also similar. This suggests that this noise-suppression method produces similar results as Kemp's non-linear method with the advantage that emission components with very short latencies can be obtained.