6ad4moletijasa2003

OTOACOUSTIC EMISSION LATENCY AND COCHLEAR TUNING

Arturo MoletiPhysics Department

University of Roma Tor Vergata

Wavelet time-frequency analysis of TEOAEs

Time-frequency analysis techniques are needed to provide accurate estimates of the TEOAE latency-frequency relation

Wavelet analysis is a useful tool because it has intrinsically good frequency resolution (and poor time resolution) at low frequency and good time resolution (and poor frequency resolution) at high frequency => good compromise for TEOAE waveforms

1-d transmission line cochlear models and TEOAE latency Propagation of the traveling wave described by 1-d transmission line cochlear models:

1-d transmission line cochlear models and TEOAE latency

The wave vector and the inverse TW velocity functions have a sharp maximum, for each frequency, near its resonant place.

If SI holds, (f)1/f If SI is violated, the degree of SI breaking is reflected in the slope of (f)

TEOAE latency and cochlear tuning

The latency of a given frequency component f can be splitted into two contributions, only one of them is a function of Q(f):

TEOAE latency and cochlear tuning

Inverting the previous relation we get an objective estimate of cochlear tuning

Cochlear tuning and SOAE minimum spacing According to coherent reflection filtering (CRF) theory the SOAE minimum spacing is given by:

If scale-invariance (SI) symmetry holds k at resonance is independent of f, thus: x = f/f = const

SI is violated by the increase of Q with frequency, =>

TEOAE latency and SOAE minimum spacing The relation between Q(f) and latency and that between Q(f) and SOAE spacing imply a relation between the two measured quantities (f) and f/f, which must be verified if CRF theory is correct.

(Moleti and Sisto, JASA 2003)