Our lab has recently reported that, if played at maximum volume settings for prolonged durations, portable digital audio players are capable of causing hearing impairment among users (Keith et al. 2008). At maximum volume settings, the sound level output ranged from 101 to 107 dBA, which, after 3 to 12 minutes, would exceed the most protective occupational noise exposure level limits set in Canada, of 85 dBA Lex(8hr) with a 3-dB exchange rate (Canadian Centre for Occupational Health and Safety 2009). We also reported that measured sound levels from portable digital audio players among a small sample of 28 university subjects ranged from 55 to 85 dBA (McNeill et al. 2010). When considered in combination with self-reported duration of daily usage, none of the subjects used their device at a level that exceeded an 85 dBA Lex(8hr) under typical listening conditions. Nevertheless, self-reported tinnitus was associated with measured volume output levels and how long people owned their device.
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