Larson Davis SoundAdvisor 831C Reference Manual page 214

Projected Noise
Dose
Single Event Noise
Exposure Level
(SENEL, LAX)
Sound
Sound Exposure
(SE)
Sound Exposure
Level (SEL, LE)
SoundAdvisor Model 831C
It is the Noise Dose expected if the current rate of noise exposure continues for
the full Criterion Duration period.
The total sound energy over a specific period. It is a special form of the Sound
Exposure Level where the time period is defined as the start and end times of a
noise event such as an aircraft or automobile passby.
The rapid oscillatory compressional changes in a medium (solid, liquid or gas)
that propagate to distant points. It is characterized by changes in density,
pressure, motion, and temperature as well as other physical quantities. Not all
rapid changes in the medium are sound (wind noise) since they do not propagate.
The auditory sensation evoked by the oscillatory changes.
Difference between sound and noise: Sound is the physical phenomenon
associated with acoustic (small) pressure waves. Use of the word sound provides
a neutral description of some acoustic event. Generally, noise is defined as
unwanted sound. It can also be defined as sound that causes adverse effects on
people such as hearing loss or annoyance. It can also be defined as the sound
made by other people. In every case, noise involves the judgment of someone
and puts noise in the realm of psychology not physics.
Rules:
1. Use word sound to describe measurements to remove the emotional overtones
associated with the word noise. Some sound metrics use noise in their name
and it is proper to use the name as it is.
It is the total sound energy of the actual sound during a specific time period. It is
expressed in Pascals-squared seconds.
where p is the sound pressure and T
A
time period). When applied to hearing damage potential, the equation is changed
to where k is the Exposure Factor. See "Exchange Rate (Q), Exchange Rate Factor
(q), Exposure Factor (k)" on page C-6.
Standard: ANSI S1.25
The total sound energy in a specific time period. The equation for it is
The sound pressure is squared and integrated over a specific period of time (T
T ) this is called the sound exposure and has the units Pascal squared- seconds or
1
T 2
2
 t   t
SE = p A
d
T 1
- T is the Measurement Duration (specific
2 1
T 2
2

t   t
p
T 1
---------------------------- -
SEL = 10Log 10
2
p 0 T
d
-
2
C-12