Where noise is a hazard and in accordance with Australian Standard AS 1319-1994, signs are to be placed at entry points.
Introduction
Hearing loss caused by noise is insidious and permanent.
Unfortunately, lost hearing is gone forever. Hearing aids offer only limited help in decoding distorted messages.
Remember, although it may seem that your ears become ‘used to’ noise, this is in fact due to temporary hearing loss. Repeated exposure to excessive noise will eventually lead to permanent damage.
Sound stimulates tiny hair-like cells in your inner ear which send messages to your brain. Under normal sound conditions these ‘hair’ cells flex and return to their normal position. However, if the sound energy is too strong and for too long the cells will break and are never repaired.
Where people have been exposed to loud noise for long periods of time and without any chance to recover, hearing damage often occurs over many years.
Describing the noise
Noise ‘loudness’ depends on the size of the sound pressure wave. The bigger the wave, the louder the noise.
However, while ‘loudness’ describes our response noise, our ears cannot assess the damage caused by noise. We need to measure the energy pressure of the noise and express it in terms of decibels (dB).
Because of the large range in noise levels that the ear can detect, the dB scale is arranged logarithmically. Although barely perceptible a 3dB increase in noise levels represents a doubling of sound energy.
A 10dB increase represents a ten-fold increase in energy levels.
These energy levels are normally measured using a sound level meter which responds to the pressure changes in sound waves. As changes in energy occur the meter averages the result.
The average represents the amount of energy your ear receives over a specified period.