Loss of hearing ability is the main health concern related to noise exposure. Noise is present everywhere. The harm caused by noise depends on the level of noise and the duration of exposure. Certain noises may be annoying, such as a buzzing noise from a light fixture or an alarm clock in the morning, but they do not necessarily pose a hazard to hearing. In offices, noise control is to prevent stress. Canadian Standards Association (CSA) Z142 provides guidelines.
In order to prevent hearing loss, throughout your life you must reduce time spent in noisy environments and use equipment to protect your ears.
In a workplace, health and safety legislation has set limits for noise exposure. Sound levels are measured in decibels (dB). Regulations for exposure levels are based on these decibel levels which are usually written as dB(A) - (A) weighting mimics the audible sounds a human ear. While the regulations are slightly different from province to province, the purpose of these limits is to prevent hearing loss in most workers. The exposure limit is given as a specific noise level in dB(A) for a specific length of exposure time. Most laws say that measures should be taken to reduce workplace noise or the exposure time if persons are likely to be exposed over 85 dB(A) noise.
Earplugs or earmuffs should be used when the source of the noise cannot be controlled in any other way. As a general rule, if the noise is so loud that you must shout to talk to people, you probably need hearing protection.
How Loud is 85 to 90 dB(A)?
The following table gives a comparison of various sources of sound and the typical level they produce:
|Source of Sound||Sound Level|
|Public spaces with dark surroundings||30|
|Wood chipper||100-110 dB(A)|
|Power mower, snowmobile||95-105|
|Salt and sand truck||90-100|
|Exposure limit, Ontario||90|
|Background noise in a quiet office||40-45|
The risk of hearing loss increases as:
- the loudness of noise increases, and
- exposure duration increases.
Types of Hearing Loss
Sudden hearing loss - after an explosion or gun shot sound.
Temporary hearing loss - after a noisy day. The hearing loss disappears after a few hours in a quiet place.
Permanent hearing loss - after noise exposure for several years or months. Such hearing loss cannot be cured by a doctor. It worsens as people become older even if there is no more noise exposure.
Tinnitus - which is a ringing or roaring sound in the ears.