Part 2: The effects of noise at work

People can lose their hearing in various ways. For example, damage to eardrum or some of the bones in 'middle ear' or even a build up of wax in the ear canal may block the transmission of sound. This is commonly known as conductive hearing loss.

In the workplace, this may occur as a result of an injury, but it is not common for employees to lose their hearing in this way.

Another type - sensorineural hearing loss - is often associated with old age and certain types of infection. It results from damage to the hair cells in the 'cochlea' within the inner ear, and the effect on hearing can be permanent.

Sensorineural hearing loss is strongly linked to the workplace as it can also be caused by exposure to excessive noise. This can be temporary, but hearing loss is also likely to become permanent if the exposure to noise is prolonged or repeated. Sometimes, the impact of prolonged exposure to noise may not be noticed until years later.

Although factories and industries using heavy machinery may be the most obvious workplaces to be affected by this type of hearing loss, others can also be impacted upon.

People working in pubs, nightclubs or music venues, for example, may also suffer, as could teachers who are repeatedly exposed to noisy classrooms and other areas of school.

Construction workers, plant operators, drivers of commercial vehicles and even office workers located too close to noisy equipment can also suffer from sensorineural hearing loss caused by work.

According to the RNID, tinnitus - a ringing, whistling, buzzing or humming noise heard in the ears or head without any external source - may be a first sign that the ear has been damaged by noise.

Tinnitus can occur suddenly or very gradually and for some people it may only be temporary. Sufferers hear noises constantly or they may come and go, and in itself the condition can be extremely frustrating.

Acoustic trauma occurs when someone is exposed to a very high sound level for a short period of time. For example, if someone is close to an explosion or gunfire.

This has recently become a concern for call-centre workers, following reports of operators' hearing being damaged by a "random frequency surge" delivered via headsets.

It is clear then that work-related hearing loss can arise from either a sudden exposure to extremely loud noise, or prolonged exposure to much lower levels. It is these factors upon which workplace regulations are based…