One hour spent listening to your favourite music on an MP3 player could lead to temporary hearing loss. A small study by researchers at Ghent University in Belgium tested the effects of listening to pop/rock music on an MP3 player in 21 young adults with normal hearing. The participants listened to the music at multiple comfortable pre-set levels (measured in decibels; maximum about 100dB) using two different types of headphones – supra-aural headphones and stock ear buds – over six sessions of one hour at least two days apart. The participants had three types of auditory measurement taken before and after the hour spent listening to music. The researchers’ June 2010 report in the Archives of Otolaryngology—Head & Neck Surgery found that at most sessions, after listening, the participants had a significant deterioration in hearing at high and low frequencies. The hearing loss was temporary and participants recovered their normal hearing between listening sessions. The authors say the temporary changes in hearing sensitivity measured by audiometry and otoacoustic emissions, indicate the potential harmful effects of listening to an MP3 player, and they call for more research to assess long term and cumulative effects.