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79th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

30.04. - 04.05.2008, Bonn

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Objective estimation of hearing threshold in humans using DPOAE measured with a pulsed paradigm method

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  • corresponding author Diana Turcanu - HNO-Klinik, Section of Physiological Acoustics and Communication, Tübingen, Germany
  • author Ales Vetesnik - Czech Technical University, Department of Nuclear Chemistry, Prague, Czech Republic
  • author Ernst Dalhoff - HNO-Klinik, Section of Physiological Acoustics and Communication, Tübingen, Germany
  • author Anthony W. Gummer - HNO-Klinik, Section of Physiological Acoustics and Communication, Tübingen, Germany

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 79th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Bonn, 30.04.-04.05.2008. Düsseldorf, Köln: German Medical Science; 2008. Doc08hno35

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/hno2008/08hno35.shtml

Published: July 8, 2008

© 2008 Turcanu et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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A recent method used for objective estimation of hearing threshold in humans employs extrapolation of input-output (I/O) functions of the cubic distortion product of otoacoustic emissions (DPOAE). DPOAE involve two generators in the cochlea: a primary generator situated near F2 and a secondary generator situated at the 2F1-F2 frequency site. It is assumed that the latter is partially responsible for deficiencies encountered in the threshold estimation method.

We investigate the possibility of removing the contribution of the secondary generator in the time domain. For this purpose, a pulsed F2 primary paradigm was used for normal hearing subjects. Using DP-grams measured in 20-Hz steps for F2=1.8–2.5 kHz, L1=0.4L2 + 39 dB and L2=25–65 dB SPL, we investigated the DPOAE signal to establish the time instant after the F2 onset when the second generator starts to contribute to the overall DPOAE amplitude. For comparison, DP-grams were also measured with conventional continuous tones.

We show that within 8–9 ms the DPOAE primary source is built up before interference with the secondary source considerably alters the DPOAE amplitude. Comparison is made with the spectral smoothing of the DP-grams measured with continuous tones.

Hearing threshold is then estimated by extrapolating DPOAE I/O function constructed from the DPOAE primary-source component separated by the pulsed paradigm method. For comparison, threshold was also estimated from the continuous DPOAE. We show that the standard deviation of the estimate obtained with the pulsed primary paradigm (6 dB) is much smaller compared with the continuous paradigm (14 dB) and the number of I/O-functions included in the analysis improves from 80% to better than 95%.

Supported by DFG Gu 194/8-1.