Noise Related Glossary of Terms
Terminology
Sound
Sound Pressure
Pascal (Pa)
Decibel scale (dB)
Sound Pressure
Level (SPL)
Sound Level
Sound Power Level
(Lw)
Noise Exposure
LEP,d
LEP,w
‘A’ weighting dB(A)
‘C’ weighting dB(C)
Attenuation
Frequency
Hertz (Hz)
Frequency Analysis
Octave-bands
Exposure Action
Values (EAV)
Lower exposure
action values
(LEAV)
Upper exposure
action values
(UEAV)
Exposure Limit
Value (ELV)
Three-decibel rule
Hearing Protection
Hearing Protection
Zone (HPZ)
Earmuff
Earplug
Noise Refuge
Description
Energy transmitted by pressure waves that is heard by the human ear.
The pressure variation of a wave in air that has a frequency within the range of the human
ear.
Unit of measurement for sound pressure.
A logarithmic number scale that allows a wide range of amplitude values to be
compressed into a small set of number values. Numbers in decibels must be treated as
logarithmic values during mathematical calculations.
A measure of sound energy expressed as a decibel value.
The SPL in decibels measured with a frequency weighting.
The total sound energy radiated by a source in watts, normally frequency weighted and
expressed as a decibel value.
A measure of the total amount sound energy a person is exposed to. It is a factor of both
the sound level and the time the person is exposed to the sound.
Daily personal noise exposure level is the amount of sound a person is exposed to in a
working day expressed as the equivalent steady sound level if sustained for eight hours.
Weekly personal noise exposure level is the amount of sound a person is exposed to in a
working week, expressed as the equivalent steady sound level if sustained for forty hours.
A-weighting is a weighting of the audible frequencies designed to simulate the frequency
response of the human ear to noise at low to moderate sound levels. A-weighted sound
levels are used to assess daily or weekly noise exposure.
C-weighting is a weighting of the audible frequencies designed to stimulate the response
of the human ear to noise at high levels. It is used for measurement of peak sound
pressure exposures.
Noise reduction through a sound barrier or hearing protector, measured in decibels.
The rate of pressure variations in the sound measured in Hertz (Hz) and heard by the ear
as pitch.
Hertz, the unit of frequency.
Analysis of a sound into its frequency components.
A division of the frequency range into bands, the upper frequency limit of each band being
twice the lower frequency limit.
Levels of exposure to noise at which certain actions need to be taken.
Daily or weekly exposure of 80 dB
Peak sound pressure of 135 dB
Daily or weekly exposure of 85 dB
Peak sound pressure of 137 dB
Taking into account hearing protector use personal exposure to noise must not exceed:
Daily or weekly exposure of 87 dB
Peak sound pressure of 140 dB
The sound intensity doubles with every 3dB increase.
Thus sounds at 88 dB are actually twice as intense as they are at 85 dB.
A term used to cover all forms of ear protection.
An area where a person is likely to be exposed at or above the daily, weekly, or peak
upper action values and which has to be demarcated with a suitable sign to conform with
Regulation 7.
Ear protection consisting of a cup enclosing the outer ear.
Ear protection in the form of a plug, which, is inserted into the entrance to the ear canal.
An operator enclosure in which a person can work away from the source of noise.