Noise - glossary

Acoustic trauma
The damage to the hearing mechanism caused by a sudden burst of high-energy noise. Acoustic trauma is usually considered to be caused by a single impulsive event with a very high peak sound level

The science of sound, including the generation, transmission and effects of sound waves, both audible and inaudible

The strength of a sound signal, as detected by the ear or as measured by a sound level meter

The reduction of the force, effect, or value of anything

Average noise level
A notional steady level that contains the same amount of noise as the actual fluctuating noise level during a specified period of time

Capability of being heard

Audiometric evaluation
A non-invasive hearing test that measures a persons ability to hear different sounds, pitches or frequencies

Testing of an individuals ability to hear various sound frequencies

Auditory threshold
The slightest perceptible sound or sound intensity required to be heard

Relating to or involving the heart and blood vessels

Case management
A collaborative process which assesses, plans, implements, co-ordinates, monitors and evaluates the options and services required to meet an individuals health, social care, educational and employment needs

An agreement between states covering a particular issue

The total or overall sound level for the whole of a noise measurement interval from the start time to the stop time, including everything that occurs during the measurement run

Daily exposure
The noise a worker is exposed to during a working day, taking account of the magnitude and duration of the noise

The unit of sound pressure, usually abbreviated to dB

Able to withstand wear, pressure or damage

Personal hearing protectors that are worn over the whole of the outer ear to minimise hearing loss in high noise levels

Personal hearing protectors that are worn inside the ear canal of the outer ear to minimise hearing loss in high noise levels

Exchange rate
The exchange rate is the amount by which the permitted sound level may increase if the exposure time is halved

Exposure action value
A daily amount of noise exposure above which employers are required to take action to control it

Exposure limit
The maximum amount of noise a worker may be exposed to on any single day

The number of times a second that a sine wave of sound, or a vibrating object, repeats itself. The more repeats per second, the higher the frequency is said to be. The unit of frequency is Hertz

Hearing threshold level
The amount, in decibels, by which an individuals threshold of audibility differs from that of a normal standard audiometric threshold

The amount of water vapour (moisture) in the atmosphere

Impulsive noise
A single or multiple sound pressure peak with a rise time or total duration less than 200 milliseconds

Induction loop
A sound system in which a loop of wire around an area in a building produces an electromagnetic signal received directly by hearing aids used by individuals who are partially deaf

Occurring at irregular intervals

Law enacted by a legislative body at the national, state or local level

Occupational physician
A doctor with specialist training and qualifications in occupational medicine

Permanent threshold shift
A permanent shift in the auditory threshold, an irreversible condition of the inner ear caused by damage to the individual hair cells in the cochlea

The reduction in human hearing acuity attributed simply to the normal ageing process

Creating or controlling a situation rather than just responding to it after it has happened

A synthetic thermoplastic material made by polymerising vinyl chloride

The process whereby an individual uses the services of various professionals to restore any functionality they've lost due to illness or injury

Temporary threshold shift
A temporary impairment of hearing acuity as indicated by a change in the threshold of audibility

A sense of ringing in the ears or noise in the head