Letters: The Truth about Bone-Conduction Earphones : The Hearing Journal

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The Truth about Bone-Conduction Earphones

Portnuff, Cory AuD, PhD; Berger, Elliott MS

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The Hearing Journal 65(6):p 4, June 2012. | DOI: 10.1097/01.HJ.0000415192.03538.d6
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While we welcome the attention to music-induced hearing loss provided by, “Hey, Teens, Listen Up!” (HJ 2012;64[4]:46; http://bit.ly/HeyTeens), this article includes exaggerations, factually incorrect statements, and the use of corporate advertising copy as fact in place of expert opinion. Our principal concerns are outlined below.

The article cites a recent publication from the International Journal of Audiology, stating that the authors found that a quarter of the participants in the study “were at severe risk for hearing loss because of their personal listening devices.” (2012;51[4]:287.) What the authors actually stated in their conclusion was, “The results of the present study demonstrate the existence of a true risk to hearing encountered by more than 25% of the young teenagers, based upon questionnaires and physical measurements.” There is a substantial difference between “true risk” and “severe risk,” and we urge The Hearing Journal to be more careful in its choice of words.

The article goes on to claim that the maximum output levels of MP3 players “can go up to 129 decibels” without giving a citation. The highest reported output level of which we are aware in peer-reviewed literature is 120 dBA, with a tight-fitting earphone. (J Acoust Soc Am 2008;123[6]:4227). While the difference between 120 and 129 dBA may seem small, a difference of 9 dBA is especially significant at these high levels. Even the value of 120 dBA is substantially higher than the levels typically measured in end-user studies, which rarely exceed 100 dBA. (J Am Acad Audiol 2011;22-[10]:663.)

Of greater concern, however, is the use of inaccurate corporate advertising copy in place of real reporting. The description of the Aftershokz bone-conduction earphones included the statement, “Because the headphones do not use the eardrums to transmit sound, they allow users to listen to music without risk of eardrum damage.” MP3 player earphones are not capable of producing levels great enough to cause an eardrum perforation, so users would not be at risk of eardrum damage from any type of earphone. Rather, listeners are at risk of cochlear damage from overuse of any type of earphone. The fact that these earphones use bone-conduction transducers does not inherently make them any safer than any other earphone, as bone-conducted sound is transduced by the cochlea similarly to air-conducted sound.

The statement about safety presented in the article is adapted from the Aftershokz website with a degree of exaggeration concerning the risk to eardrum damage and without review of the original or adaptation by The Hearing Journal's editorial advisory board. We would urge a more thorough vetting of marketing statements prior to their publication.

Cory Portnuff, AuD, PhD

Denver, CO

Elliott Berger, MS

Indianapolis, IN

© 2012 Lippincott Williams & Wilkins, Inc.