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Significance of a notch in the otoacoustic emission stimulus spectrum

Published online by Cambridge University Press:  17 July 2012

J Grenner
J Grenner*
Affiliation:
Department of Clinical Sciences, Lund University, Lund, Sweden ENT Department, Scania University Hospital, Lund, Sweden
*
Address for correspondence: Dr Jan Grenner, ENT/Audiology, University Hospital, SE 221 85 Lund, Sweden Fax: +46 46 172912 E-mail: [email protected]
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Abstract

Objective:

To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media.

Methods:

The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied.

Results:

Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately −185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment.

Conclusion:

A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.

Keywords

Ear, MiddleOtitis MediaOtoacoustic Emissions
Type
Main Articles
Information
The Journal of Laryngology & Otology , Volume 126 , Issue 9 , September 2012 , pp. 897 - 901
Copyright
Copyright © JLO (1984) Limited 2012

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References

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2Konrádsson, KS, Svensson, O, Carlborg, B, Grenner, J. Tympanic pressure gradients and otoacoustic emissions. Ear Hear 1999;20:403–9CrossRefGoogle ScholarPubMed
3Grenner, J. Handbook of Practical OAE Measurements [in Swedish]. Stockholm: CA Tegnér AB, 1999Google Scholar
4Marshall, L, Heller, LM, Westhusin, LJ. Effect of negative middle-ear pressure on transient-evoked otoacoustic emissions. Ear Hear 1997;18:218–26CrossRefGoogle ScholarPubMed