DPOAE tests for assessing possible hearing loss caused by extensive use of MP3 players

During the last year, newspapers around the world have reported that surveys indicate that excessive use of MP3 players may damage the hearing.

The dangers of MP3 players
The problem with MP3 players is that the volume on many of them can be turned up to more than 100 dB HL. As many of these music players are used in noisy surroundings and with typical in-the-ear headphones that do not completely attenuate the ambient noise, higher listening volumes are typically used.

With batteries on a typical MP3 player lasting up to 12 hours many young people listen to the music at very high levels for extended periods of time, which may lead to temporary hearing loss or in the worst case permanent hearing loss.

Measuring temporary and permanent threshold shift
When the ear is exposed to high music for long periods of time, the hair cells might be damaged and lead to temporary or in the worst case permanent threshold shift.

According to researchers at Aalborg University, Denmark, measuring OAEs (otoacoustics emissions) before and after noise exposure suggests that OAE is a more sensitive method than pure-tone audiometry and therefore might be a method for early identification and monitoring of hair cell damage which in turn may lead to hearing loss.

OAE tests to assess the consequences of high level sound exposure
The greatest effect of a temporary hearing loss due to noise exposure is recorded 2 minutes after the exposure. If the hearing improves after some time the patient is suffering from temporary hearing loss. If the OAEs do not improve by days and weeks the patient may have a permanent hearing loss.

With the DPOAE20 system from Interacoustics® it is possible to use the I/O and high resolution versions of the DP-gram tests to make a very detailed recording of OAE, which may be helpful in assessing the consequences of high level sound exposures from e.g. MP3 players. This can be done also as an educating tool, demonstrating the consequences of loud MP3 use for people at risk for this type of hearing damage.

Sources: “Digital music craze stores up ear trouble for iPod fanatics”, Scotland on Sunday, 8 May 2005, by Richard Gray, ”Really?”, New York Times, 6 September 2005, by Anahad O'connor, “Repeatability of DPOAEs and their vulnerability to over-exposure”, Conference Article from DAGA 2003 in Aachen, Germany, by Reuter, Karen : Ordonez, Rodrigo : Hammershøi, Dorte