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Re: average(?) of spontaneous otoacoustic emissions

Dear Bruno and others,

Interesting question. With the currently most advanced measurement technique, which has been in use since 1990 (!), the bulk of human spontaneous otoacoustic emissions (SOAEs) was recorded in the 1-4 kHz range. Therefore an "average spectrum" does not "make sense".

There is not even one mode, somewhere in this range. In fact, there are two modes, one at 1.5 kHz and one at 3 kHz, with a sharp dip in the distribution curve at 2.14 kHz.

The bimodality appeared first in 1993 in Fig. 6, but without being mentioned in the text, in:

A detailed analysis of the bimodality appeared in 2006:

The data that were recorded by Zwicker's doctoral students Eberhard Schloth and Christoph Dallmayr in the early and mid-1980s and were later republished by Zwicker and Fastl in 1990 (not 1999; Zwicker died in 1990) are unfortunately outdated. Even the best data that we have today, those that were collected around 1990, still reflect measurement limits.

Yes, SOAEs are perhaps the most thrilling phenomenon in the hearing machine. David Kemp, who made them to a fact in the late 1970s, should long have been given a Nobel Prize for his work. The reason why this did not happen is as simple as sobering. The committee would have been unable to say what he discovered.

There is still no generally accepted understanding of how and why SOAEs are generated. Due to several false beginnings in the field of cochlear mechanics, as often discussed on this list, many simply applied the first law of science:

"If we don't understand it, it can't be relevant."

Have a nice day.


Martin Braun
Neuroscience of Music
S-66492 Värmskog
email: nombraun@xxxxxxxxx
web site: http://www.neuroscience-of-music.se/index.htm

Subject: Re: average(?) of spontaneous otoacoustic emissions
From:    "Bruno L. Giordano"  <brungio@xxxxxxxx>
Date:    Tue, 7 Aug 2012 15:11:05 +0100

Dr. Reinhart Frosch kindly referenced this figure:

Fig. 3.12 of Zwicker and Fastl, Psychoacoustics, Springer, 2nd ed.
(1999), is a two-dimensional representation (SPL versus frequency) of
SOAEs from about 100 normal ears.



On 07/08/2012 1:48 PM, Bruno L. Giordano wrote:

I would like to take a look at the spectrum of spontaneous otoacoustic
emissions averaged across a possibly large number of normal-hearing

Can someone please suggest a reference? Does an average spectrum make
sense when considering the amount of interindividual differences?

Thank you,