Many workplaces permit employees to listen to MP3 players—especially in factories or at work sites where noise volumes are hazardous or distracting. But using MP3 players (such as iPods) as noise-canceling devices can cause noise-induced hearing loss (NIHL) if listeners crank up the volume.
Guidance on noise-induced hearing loss from the National Institutes of Health's National Institute on Deafness and Other Communication Disorders says that "repeated exposure to sounds at or above 85 decibels can cause hearing loss." Many experts cite 80 decibels as the danger level—roughly equivalent to the sound of heavy city traffic.
"I see employees wear MP3 players while working all the time, and I know they are listening to them at least 5 or 10 dB above background," says Elisabeth Black, certified industrial hygienist. "I think it is a major problem, the results of which won't become apparent for a while—until it is too late for many."
Noise-induced hearing loss is painless and is not immediately noticeable. Gradual loss can take place for years before people start to realize they can't hear as well as they used to—sounds are distorted or muffled. Speech becomes harder to understand. And noise-induced hearing loss is permanent. Hearing acuity, once lost, cannot be restored.
A danger-awareness video called "My iPod Can Destroy My Hearing?? Say What??" from the Mountain and Plains Education and Research Center at the Colorado School of Public Health tells "how loud is too loud" and describes how to prevent MP3-induced hearing loss.
The video lists these prevention measures:
- Use noise-canceling headphones or earbuds to block out ambient noise (so you won't have to turn up your MP3 player so loud).
- Set a volume limit on your MP3.
- At least every 45 minutes, take a break from listening to your MP3.
A more immediate danger to MP3-listening workers, notes Elisabeth, is failure to hear work-site warnings or hazard communications.
For more information, Macworld.com offers an excellent overview of hearing safety and MP3 players.