Quiet please! Fighting noise pollution
Box 1 | Health issues related to noise pollution
Although we recognise noise pollution as a major environmental problem, it is difficult to quantify the effects it has on human health. Exposure to excessive noise has been shown to cause hearing problems, stress, poor concentration, productivity losses in the workplace, communication difficulties, fatigue from lack of sleep, and a loss of psychological well-being.
Extreme noise
At its most extreme, loud noise can cause instant and permanent hearing loss. Normal hearing depends on the three components of the human ear: the outer, middle and inner ear. The inner ear or cochlea is the most susceptible to damage by loud noises. It contains thousands of tiny hair cells that transmit sound impulses to the auditory nerve. Explosive sounds with peak noise levels of 140 decibels (dB) or more can destroy these cells and cause permanent deafness. Extended exposure to loud noise can also lead to long-term hearing loss.
A sound level meter is used to measure the decibel levels of sound. Usually the sound level meter has a filter that has a frequency response similar to the human ear. These levels are known as dB(A) or A-weighted decibels. Like the ear, this filter reduces the sound levels in the lower frequencies (below 1000 hertz) and in the higher frequencies (above 5000 hertz).
Worksafe Australia recommends that a noise level of 85 dB(A), sustained for no more than 8 hours a day, should be the maximum to which a worker is exposed. This is about the same as the noise level in a street with heavy traffic. Higher noise levels can cause permanent hearing loss unless protective measures are taken.
Damage to more than hearing
Aside from contributing to hearing loss, too much noise can affect human health in many other ways. Research has shown that people living near airports or busy roads have a higher incidence of headaches, take more sleeping pills and sedatives, are more prone to minor accidents, and are more likely to seek psychiatric treatment.
Exposure to high noise levels has also been shown to lead to a range of physical symptoms such as accelerated heartbeat, high blood pressure, gastro-intestinal problems and chronic fatigue. Some of these problems are relatively easy to treat medically, but other psychological effects such as insomnia, nervousness, anxiety and depression can be longer lasting.
Boxes
Box 2. What is noise?
Box 3. Planning to reduce airport noise
Box 4. Traffic noise – sources and solutions
Box 5. Soundproofing noisy buildings
Related sites
Effects of noise (New South Wales Environment Protection Agency, Australia)
Noise – auditory effects (Canadian Centre for Occupational Health and Safety)
How hearing works (How Stuff Works, USA)
The physiology of hearing (Avatar Space Design, Australia)
Cochlear implants – wiring for sound (Nova: Science in the news, Australian Academy of Science)
Page updated February 2007.