Turning down the decibels.

Turning Down The Decibels

Courtesy of the
Hearing Foundation of Canada

Noise is still the biggest cause of permanent disability claims settled by the Worker's Compensation Board in Ontario, Canada.

It's a noisy world out there. And from power lawn mowers to booming theatre speakers to buzzing communications devices, it's just getting noisier.

In fact, experts say the world in which we live is getting noisy enough to damage our hearing--permanently.

When it comes to noise and hearing loss, researchers like Dr. David Brown, Audiologist and Auditory Researcher at the University of Calgary's Faculty of Medicine, say that most Canadians have got only half the message. These days most people know that they need to protect themselves - in the workplace.

The law requires it. In Ontario, workers must wear ear protection when the noise reaches 90 decibels. They can work at this level for eight hours. As the volume on the job increases, workers exposure time decreases. And when it reaches 115 decibels for example, the Ontario Occupational Health and Safety Act and Regulation (1990) demands that worker exposure time be reduced to only 15 minutes. And no worker should endure anything over 155 decibels (a volume for a 100-watt stereo), according to The Hearing Foundation of Canada at any time.

It's a good thing, since about 35 per cent of all workers in heavy industry are exposed to dangerous levels of noise, according to The Foundation. Even with a general understanding that hearing should be protected, noise is still the biggest cause of permanent disability claims settled by Worker's Compensation Board in Ontario.

Experts like Dr. Brown say the guidelines are not strict enough. They'd like to see less exposure time at still fewer decibels. But what worries audiologists even more, Dr. Brown says, is damage that can occur when people aren't on the job. People are usually very surprised to discover that prolonged exposure to things like Walkmans, power lawnmowers, and even loud toys can damage their hearing.

Technically there are two types of hearing loss related to noise. Both types occur when sound transmitting hair cells in the inner ear become damaged and can't signal the auditory nerve to send electrical impulses to the brain.

One type of loss is acoustic trauma -- an immediate, severe and persistent hearing loss that can result from a short burst of intense sound like gunfire or fireworks.

The second type is gradual, cumulative, noise-induced hearing loss. Eighty-five decibels is the level at which hearing damage can occur after exposure of eight hours or more. Repeated exposure over time causes permanent and irreversible hearing loss.

"The thing is, we don't do anything in isolation", says Dr. Brown.

"Most of what we do to damage our hearing is cumulative. And noise damage occurs depending on how loud the sound is and how long you hear it."

"Look at your vacuum cleaner," Dr. Brown continues. "They come in now at 94 dB. So you run your vacuum cleaner for an hour. At 94 dB you could get away with about five hours worth of exposure. But how many times do you do that in isolation? More likely, you turn up your Walkman while you're vacuuming (85dB at volume level two). And then watch some TV (70-90 dB). Maybe go to a game. A major sporting event typically comes in at 100 dB. If the guy behind you has one of those air horns, those things are about 126 dB at three feet.

Even the dial tone on the telephone is 85 dB. And almost all sounds, regardless of their pitch, are equally damaging to your hearing. A bass guitar can be as damaging as a flute--and there is little difference between the exposure to Beethoven's Fifth (symphony orchestra - 110 dB) and an assembly line in a factory. According to The Foundation research the worst culprits can be loud stereos, concerts, and loud cars. Regular exposure of more than one minute risks permanent loss of hearing.

Hearing loss is called the hidden disability. Part of the problem is that gradual loss is easy to ignore and hard to predict precise levels of loss since it depends on duration and number of exposures over years. But researchers at Queen's University reported hearing loss in one third of 60 students who had never been exposed to industrial noise and who claimed to take part regularly in activities such as listening to stereo music, playing in bands and playing video games.

"When 15 percent of school age kids are hearing impaired according to U.S. statistics," Dr. Brown says, "we know we've got problems.

"What is to be done? First thing, when you can - turn down the volume. Be aware of the cumulative effect of environmental noise. People can also pressure manufacturers to produce quieter products and toys and get regular hearing tests. And wear hearing protection.

Dr. Brown says hearing protection has come a long way and today, "basically there are hearing protections for anybody"

He has earmuffs he wears to cut his lawn, and you can get them for kids too. There are foam and rubber earplugs, which can also be custom made. There are special plugs for musicians, which allow them to hear their music but cut out damaging flat tones.