Warwick Williams, National Acoustic Laboratories
www.nal.gov.au
Anecdotally it had been frequently claimed that, young people in particular, were damaging their hearing by frequent use of earphones in conjunction with personal stereos.
Past research at the National Acoustic Laboratories, 
based on questionnaires about personal stereo use showed that heavy users of personal stereos had more hearing damage than those who did not use them.
The aim of the research project was to directly test whether people listened at levels high enough to cause hearing damage, in real-life condition.
Test subjects were selected randomly from crowds outside Flinders Street Station, Melbourne, and Sydney Town Hall. Passing individuals who were using personal stereos were asked to participate by allowing the experimenter to place their headset on an artificial ear in order to measure the sound level and simultaneously to respond to several questions concerning personal stereo use.
The estimated noise exposure level (calculated from the sound level multiplied by the time of use) was compared to the limits of noise exposure considered acceptable in workplace OHS regulations throughout Australia.
The results showed that around 25% of users had daily noise exposures high enough to eventually cause hearing damage. Some users were well above the limit at which damage occurs.
The age of users ranged between 15 and 48 years with a mixture of male and female subjects.
The research was published in International Journal of Audiology 2005; 44:231-236.
