Maybe a sledgehammer is what we need?

Marshall Chasin
May 9, 2017

I know that it is a great pastime for all of us to take a few moments and go through our old journals to see if we missed any important articles. Well, I ran in to this old article which I had marked for future reading and even had downloaded a pdf.  It was sitting in a file called READ THIS. Obviously I don’t follow directions well. It is called “Impact of three hours of discotheque music on pure-tone thresholds and distortion product otoacoustic emissionsand appeared in the October 2010 issue of JASA.

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My initial reaction was “I am actually not sure how this 2010 publication could have seen the light of day” given the previous publication of a ream of articles in the mid-2000s about how the effects of music and noise exposure resolve over a number of hours (TTS) if only cochlear phenomena are examined, but that there can be remaining neural pathologies which do not resolve. Using cochlear measures is like using a sledge hammer where a fine toothed comb is probably a better tool.

Puretone thresholds and otoacoustic emission results assess the sensitivity and the function of the cochlea but are insensitive to permanent neural pathologies that may be the result of loud music or loud noise.

Then, my second reaction started to sink in.  Well, if we do see changes in these blunt sledgehammer-like measures, then something major may be going on and perhaps we shouldn’t throw the baby out with the bathwater.

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In this article, subjects were exposed to 3 hours of disco music. The effects of this rather brief exposure were measured with high resolution pure tone TTS measures in the 3500-4500 Hz region as well as optoacoustic emission testing using the same “before” and “after” TTS paradigm. 

The intent of the article was not really to find an effect (which would have been evident at the neural level manifest as a delayed wave I or an altered SP/AP ratio). Rather, it was to see if otoacoustic emissions (which are relatively easy to do as opposed to the more laborious and subjective pure tone thresholds) were sufficiently correlated.

Indeed they were correlated once some calibration issues were controlled. This bodes well for using high resolution otoacoustic emission testing to assess some parameters of temporary threshold shift. Of course, the puretone threshold elevation and the changes in otoacoustic emission testing resolved after a period of time.

The point is that we have something that we can use other than puretone threshold shifts to assess temporary hearing loss or TTS, and we are OK as long as we understand the limitations of TTS measures.

I could have titled this blog “Don’t throw the baby out with the bathwater”, which was exactly what I was doing.  And this is such an awful phrase, I promise not to ever use it again!

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