6ad4moletijasa2003

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6ad4moletijasa2003

  1. 1. OTOACOUSTIC EMISSION LATENCY AND COCHLEAR TUNING Arturo Moleti Physics Department University of Roma Tor Vergata
  2. 2. Wavelet time-frequency analysis of TEOAEs <ul><li>Time-frequency analysis techniques are needed to provide accurate estimates of the TEOAE latency-frequency relation </li></ul><ul><li>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 </li></ul>
  3. 3. 1-d transmission line cochlear models and TEOAE latency <ul><li>Propagation of the traveling wave described by 1-d transmission line cochlear models: </li></ul>
  4. 4. 1-d transmission line cochlear models and TEOAE latency <ul><li>The wave vector and the inverse TW velocity functions have a sharp maximum, for each frequency, near its resonant place. </li></ul><ul><li>If SI holds,  (f)  1/f </li></ul><ul><li>If SI is violated, the degree of SI breaking is reflected in the slope of  (f) </li></ul>
  5. 5. TEOAE latency and cochlear tuning <ul><li>The latency of a given frequency component f can be splitted into two contributions, only one of them is a function of Q(f): </li></ul>
  6. 6. TEOAE latency and cochlear tuning <ul><li>Inverting the previous relation we get an objective estimate of cochlear tuning </li></ul>
  7. 7. Cochlear tuning and SOAE minimum spacing <ul><li>According to coherent reflection filtering (CRF) theory the SOAE minimum spacing is given by: </li></ul><ul><li>If scale-invariance (SI) symmetry holds k at resonance is independent of f, thus:  x =  f/f = const </li></ul><ul><li>SI is violated by the increase of Q with frequency, => </li></ul>
  8. 8. TEOAE latency and SOAE minimum spacing <ul><li>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. </li></ul>(Moleti and Sisto, JASA 2003)

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