When considering what noises is so loud it could cause hearing damage, most people would think of loud motors, trains, planes, and jackhammers. A recent study from the University of Michigan and University of California, San Francisco finds there is another major player in hearing damage: mp3 players and other stereo usage.
Researchers have traditionally believed it was noise in the work place which is the major contributor to hearing loss. The focus of the study was actually to find what the average annual noise exposure is for people using public transportation (the study specifically used residents of New York City) and comparing it to that of those who do not use transportation. Surprisingly, the transit system, on its own, only accounts for a tenth of the excessive noise levels transit users would subject to. When considering all noise sources, the primary cause of exceeding the recommended 125 db limit, was mp3 players and stereo usage. Some 90% of transit users and 87% of non-transit users were exposed to these high volumes.
This unexpected discovery does worry some as even momentary exposure to noises above 125 db can cause permanent damage. Persistent exposure can also lead to other health problems including stress, sleep problems, and even heart disease. Might not be a bad idea to turn it down a few notches.