Wavelet and matching pursuit estimates of the transient-evoked otoacoustic emission latency

Abstract

Different time-frequency techniques may be used to investigate the relation between latency and frequency of transient-evoked otoacoustic emissions. In this work, the optimization of these techniques and the interpretation of the experimental result are discussed. Time-frequency analysis of click-evoked otoacoustic emissions of 42 normal-hearing young subjects has been performed, using both wavelet and matching pursuit algorithms. Wavelet techniques are very effective to provide fast and reliable evaluation of the average latency of large samples of subjects. A major advantage of the matching pursuit technique, as observed by Jedrzejczak et al. [J. Acoust. Soc. Am. 115, 2148-2158 (2004)], is to provide detailed information about the time evolution of the response of single ears at selected frequencies. A hybrid matching pursuit algorithm that includes Fourier spectral information was developed, capable of speeding-up computation times and of identifying "spurious" atoms, whose latency-frequency relation is apparently anomalous. These atoms could be associated with several known phenomena, either intrinsic, such as intermodulation distortion, spontaneous emissions and multiple internal reflections, or extrinsic, such as instrumental noise, linear ringing and the acquisition window onset. A correct interpretation of these phenomena is important to get accurate estimates of the otoacoustic emission latency.

A mechanism for simultaneous suppression of tone burst-evoked otoacoustic emissions

“…less than approximately 2 ms post-stimulus onset (e.g. Siegel et al, 2005;Notaro et al, 2007;Withnell et al, 2008), they will be removed from the response waveform as a consequence of discarding early waveform segments dominated by unwanted stimulus 5 ringing. It is therefore unlikely that basal-source TEOAE components play a significant role in simultaneous suppression of TBOAEs.…”

“…However, because of their short latency (Siegel et al, 2005;Notaro et al, 2007;Withnell et al, 2008), basal-source response components would have been removed prior to analysis (along with unwanted stimulus components) making it unlikely that they could influence suppression. This will also have been the case for previous reports of simultaneous suppression of TBOAEs (Xu et al, 1994;Yoshikawa et al, 2000;Killan and Kapadia et al, 2006).…”

“…However, in order to make more confident conclusions 22 about the role of basal-source components in the production of simultaneous suppression of TBOAEs, further investigation would be required. To this end, a detailed parametric study, utilising time-frequency analysis techniques that allow decomposition of TBOAEs based on their likely origin (Notaro et al, 2007;Goodman et al, 2009) is currently being undertaken.…”

Further tests of the local nonlinear interaction-based mechanism for simultaneous suppression of tone burst-evoked otoacoustic emissions

“…Verhulst et al, 2012), recording techniques that allow the early portions of the TBOAE response waveform to be preserved (e.g Keefe, 1998) and analysis techniques that decompose the TBOAE response in to components based on their likely origin (e.g. Jedrzejczak et al, 2004;Notaro et al, 2007). Such investigations are warranted given the implications that the conclusion of a combined suppression mechanism, and therefore 40 TBOAE generation mechanism, has for the diagnostic use of TBOAEs in the clinical setting.…”

“…Because of its short latency, this component is assumed to be generated at basal regions of the basilar membrane (BM) via two possible mechanisms; nonlinear intermodulation distortion (e.g. Yates and Withnell, 1999;Carvalho et al, 2003;Withnell and McKinley, 2005;Notaro et al, 2007;Withnell et al, 2008) and linear reflection (Goodman et al, 2011;Moleti et al, 2012;Sisto et al, 2013). Recent modelling efforts suggest that the second of these mechanisms, the basal-reflection mechanism, is most likely to account for the short-latency, basal-source component .…”