How can loud noise cause tinnitus?

Long-term exposure to loud noise is being increasingly attributed to the development of tinnitus.

The exact process by which noise damages the hearing mechanism is not yet fully understood, though scientists believe that the metabolism of the inner ear sensory cells is disturbed by over-stimulation. What is clear is that repeated exposure to high intensity sounds can lead to a weakening of the delicate hair cells in the inner ear leading to their eventual breakdown. This means that, at first, any damage is temporary. However, if the noise exposure continues, or if the ear is not given enough time to recover, the hearing damage becomes permanent and irreversible.

Up to 30 per cent of the ear's 15,000 hair cells will have been destroyed before an individual becomes aware of hearing loss. The development of tinnitus can be a first sign that damage has occurred.

Whether as a precaution or to avoid the worsening of tinnitus symptoms, it is advisable to avoid excessive noise.

How loud is too loud?

As examples of noise levels in everyday life, an average conversation will reach around 60 dBA while a busy street can peak at 80-90 dB. 120 dB is louder than a pneumatic drill and a noise level that can be reached in nightclubs. Exposure to a noise level of 140 dB causes immediate injury to an unprotected ear (although exposure to noise at this level is unusual).

There is a danger of hearing damage including tinnitus where people are regularly exposed to levels of noise of generally 80 dBA or more.

Legislation covers many sources of noise we encounter in everyday life. Employers have to abide by The Control of Noise at Work Regulations 2005 (except for the music and entertainment sectors who will continue to use the 1989 regulations until 6 April 2008) while products on sale to the public are covered by British and European Safety Standards.

Ultimately we have to take responsibility for protecting our own ears against tinnitus and hearing loss. It is important to remember too that no two people will have an identical tolerance to noise, with research suggesting that a genetic predisposition towards hearing loss is an important factor.