HEALTH WATCH

Waimarino Bulletin, Volume 6, Issue 271, 24 January 1989, Page 13

HEALTH WATCH

The effects of noise on hearing are not precisely known and uncertainties exist. However, there is sufficient information available for some prediction of the hazardous effects of noise on human hearing.

Noise may affect hearing in three ways - Acoustic trauma: This is the physical damage of the ear from a single exposure to very high sound levels. Damage is immediate and usually results in

some permanent hearing loss. Noise induced temporary threshold shift: This is the short-term loss of hearing sensitivity immediately following noise exposure. In

most cases, provided no further exposure occurs during recovery, full hearing will return. Noise induced permanent threshold shift: This is often normally the result of repeated exposure to excessive noise over a period of many years.

The noise has damaged and destroyed sensitive cells in the ear. The effects on hearing from excessive sound from music is not clearly understood. Over a period of time it has been possible to build up a picture of the effects of noise in industry, since exposure is normally regular and predictable. This kind of information is not available in respect of recreational noise. Two factors are of equal importance in respect of exposure to noise, the level and the length of time of the exposure. It is probable that exposure to live or recorded music on a weekly or infrequent basis will not, by itself, cause permanent damage to hearing. (as long as the levels are not exces-

sive and don't cause acoustic trauma). It is however, possible that a person who works in a noisy job may, by the addition of further noise at a Nightclub or Disco, be exposed to an amount of noise during the day or week which could cause damage to hearing in the long term. Band members and their support crews may also be exposed to potentially damaging amounts of noise if they are working regularly. The extent of this problem is uncertain as only a relatively small amount of work has taken place in this regard. It is good practice to avoid exposure to any loud noise. Where this is not possible, hearing protection should be wom. If noise is of such a level that pain occurs in the ear, damage has probably oc-

curred and it is also probable that a permanent hearing loss will result. If after exposure to loud noise a ringing sound can be heard (tinnitus) or some loss of hearing sensitivity is noticeable, then a temporary hearing loss has occurred, which with repeated exposures to noise of similar levels, may result in a permanent hearing loss. Once the delicate hearing cells in the ear have been destroyed, the resulting loss to

hearing is permanent. It is therefore important that care is taken to prevent this damage. This is of greater significance to people who already have some loss of hearing. Further abuse of fhese cells through exposure to loud noise will increase the hearing loss. If you would like further information, please contact the Health Protection Officers or Public Health Nurses at the Community and Environmenta1 Health offices.