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Residual Noise
This is the ambient noise remaining under normal conditions when any specific
noise sources under investigation (for assessing the likelihood of complaints) are
suppressed to a degree such that it does not contribute to the ambient noise.
See also ‘Ambient Noise’.
Root Mean Square (rms)
The abbreviated term rms is identified from the expanded term root mean
square, also known as the quadratic mean.
The root mean square of a value is calculated by finding the
square Root
of the
Mean
of the
Squares
of the values.
Sound meter instruments use the rms sound pressure level for function
calculations other than when the peak level is required.
See also ‘Peak Level’.
Sound
This is a travelling wave or a disturbance in pressure which propagates through
mediums such as solids, liquids or gases. Sound cannot travel through a
vacuum.
The wave will compose of frequencies within the audible frequency range and be
of sufficient amplitude for detection by the ear. See also ‘Audio Frequency
Range’.
Sound Exposure (SE)
This is a measure of the total A-weighted sound energy of the sound produced
over a specified period of time.
It is specifically defined as the time integral of the square of sound pressure over
a stated period of time and expressed in Pascal squared seconds if the A-
weighted sound pressure is in Pascal’s and the time period is in seconds.
SE
t1
t2
t
P
A
( )
2
t
( )
⌠
⌡
d
:=
where PA is the A-weighted sound pressure and t2-t1
is the time interval for the
measurement or specified time period, in seconds.
