Threshold and DPOAEs
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- Category: DPOAEs
- Last Updated on Wednesday, 05 December 2012 17:31
- Written by Stavros Hatzopoulos
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The relationship between DPOAEs and Audiometric outcomes (mainly with the Pure Tone Audiometry) has been also a debating issue from the early days of otoacoustic emissions. While it is known that hearing impairments higher than 30 to 40 dB HL cause a significance decrease of the TEOAE responses, the same it is not valid for DPOAE recordings. Due to the efficiency of the DPOAE stimulation schemes it is possible to record responses even from cases presenting hearing losses as high as 50 dB HL.
The true debate on the issue of threshold and DPOAEs revolves around the prediction of the auditory threshold by the signal values of the DPOAEs. In this context it can be said that in general the DPOAES cannot predict the Auditory threshold. The reason for the latter is the fact that auditory perception involves more parts of the auditory system than just the periphery whose function is reflected by the DPOAE measurements.
Neverthess when:
- The external and middle ear functions are normal.
- There are no retrocochlear hearing complications
the audiometric outcomes and the information from the DPOAEs are in agreement. Any deviation from this scenario causes a disagrerement between the DPOAEs and the audiometric outcomes.
Recent research findings in the relationship between the auditory threshold (in neonates) and DPOAE signal values have provided interesting speculations which might lead to an acceptible threshold prediction. The reader can consult the following extra sources in the Portal :
- On the Prediction of cochlear pure-tone threshold and cochlear compression by means of extrapolated DPOAE I/O-functions by Thomas Janssen, Ph.D. December -January 2004 (Editorial) .
- DPOAE I/O Functions in Normal and Impaired Human Ears by Mike Gorga et al (future PowerPoint Presentation)