Effects of pink background noise, song selection, and iPod volume levels on the audibility of songs to bystanders
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Type of Workapplication/pdf
ix, 71 pages
DepartmentTowson University. Department of Audiology, Speech-Language Pathology and Deaf Studies
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There are no restrictions on access to this document. An internet release form signed by the author to display this document online is on file with Towson University Special Collections and Archives.
Recently, media attention has been focused toward the effects of personal mp3 players and their potentially damaging effects on hearing when listening at high levels. The current study aimed to determine whether the ability to overhear someone else's iPod from a distance away was indicative of dangerous listening levels, or levels greater than or equal to 85 dB(A). An iPod Touch with standard earbuds was placed on a KEMAR mannequin in a sound treated test suite. The output from the iPod was recorded and measured from 2 feet four inches away to simulate a passer-by. Stimuli included five popular songs at nine volume settings on the iPod ranging between 0 and 100 percent volume. Recordings were mixed with four background noise conditions: quiet (31.6 dB(A) ambient noise, 45 dB(A), 60 dB(A), and 75 dB(A) of pink noise and played through an eight speaker array. Fifty participants (mean age of 23 years) with normal hearing were recruited to participate in the study. They were seated in the center of the sound treated booth and instructed to say "yes" when they were able to hear the music stimuli over the background noise. The results suggested that when listening in a quiet setting, participants were likely to overhear someone else's iPod; however, the probability that the song had a long-term average output level than or equal to 85 dB(A) FFE was low. As background noise levels increase, the ability to overhear iPods decreases. Positive predictive value increased for the louder background noise conditions indicating that if a person is able to overhear someone else's iPod in noisy listening setting, it is more likely that the person is listening at a level greater than or equal to 85 dB(A). In the loudest background noise condition of 75 dB(A), the background noise completely masked all of the songs rendering them inaudible to the listeners, even songs with peak outputs greater than or equal to 85 dB(A). This study concluded that the ability to overhear someone else's iPod does not necessarily indicate they are listening at a dangerous volume level, and not overhearing someone's iPod does not necessarily indicate they are listening at a safe volume level.