Study: Even normal noise exposure can be dangerous

By Ian Dillingham, Daily Staff Reporter
Published December 7, 2013

Does danger lurk in your iPod?

Thursday, Public Health Assistant Prof. Richard Neitzel and a team at the School of Public Health published findings related to the dangers of prolonged exposure to noise. Neitzel said noise is often overlooked as a potential health hazard, both in occupational settings and daily life. While people often associate loud noises with hearing loss, prolonged exposure to even moderate noise levels may have other serious health consequences, including high blood pressure and heart attack.

Following his research appearing in the journal Environmental Health Perspectives, Neitzel said he hopes the paper will reenergize the conversation about noise as a health hazard — a topic that has seen little research over the last several decades.

“(Noise) is something almost no one thinks about, compared to something like air pollution,” Neitzel said. “In a way, it’s like the wild west of exposures in that we tolerate it being there and haven’t looked into it much, really since the 1970s.”

Neitzel conducted the first portion of his research in New York City, where he studied environmental factors that contribute to hearing loss. Surprisingly, he found that most people were “driving their own exposure” through music, even though they may not think they’re listening to it very loudly. Subjects also suffered from involuntary exposure on subways and in the workplace.

In a dangerous twist, Neitzel said the more serious consequences, such as heart attacks, occur at lower levels than required for hearing loss. Thus, individuals may not realize they are being over-exposed.

Hearing loss has the potential to occur if a person’s average exposure over 24 hours exceeds 70 decibels, or about as loud as a normal conversation, according to Neitzel.

“You can certainly have high noise during the day, you just need to have periods of quiet as well so it all averages out,” Neitzel said.

However, for students, exposure can potentially be much higher. Attending a noisy party or rock concert can expose individuals to levels as high as 110 decibels, which represents a 10,000-fold increase from the minimum level necessary for hearing loss.

“Any time you have ringing in your ears after noise — some people get a sensation that the sound is muffled — that’s basically the only way your body has to tell you that’s too much noise,” Neitzel said. “If you are leaving a noisy event, and your ears are ringing, or it sounds like you’re underwater, that’s a sign you got too much noise and probably ought to not do that again.”

Many people ignore such ringing because it does not hurt, but Neitzel said ears do not actually hurt until about 125 decibels, which is well above the level necessary for hearing loss.

Ann Arbor City Code of Ordinances states that individuals cannot undertake any activity that produces over 61 decibels of noise beyond their property line between 7 a.m. and 10 p.m. Between 10 p.m. and 7 a.m., the permitted level drops to 55 decibels.

While this code provides basic protection from most noise dangers, Neitzel said most municipal police forces around the United States are ill-equipped or too busy to enforce noise regulations.

“There are many towns where there are no rules at all,” Neitzel said. “Cities don’t have the resources on their own, for the most part, to take on noise as a problem.”

Some cities, like San Francisco, now require concert venues to provide or sell hearing protection to patrons. But despite such efforts, noise hazards have yet to gain the same level of national regulation that other hazards, such as air pollution, have received.

“Cities and counties are just sort of making it up as they go, rather than us taking a comprehensive look and saying let’s do this right,” Neitzel said. “Some cities have taken the right steps, such as Ann Arbor, but most have not.”