SoundAdvisor Model 831C
C-5
units, like sound pressure in acoustics or voltage in electrical engineering. This is illustrated in
equation below:
Table C.1 illustrates how a a tenfold increase of the sound pressure will result in an increase in 20
dB steps, while sound power increases in 10 dB steps. See the linear form (Table C.1) and compare
with equation above. In conclusion, dB values are always the same, independent of using sound
power or sound pressure as the base unit. A 6 dB increase implies four times the sound power or
two times the sound pressure.
Department of Defense Level (LDOD)
The Average Sound Level calculated in accordance with Department of Defense Exchange Rate
and Threshold Level. See
.
Dose
See
Detector
The detector converts the actual fluctuating sound from the microphone into a signal that indi-
cates its amplitude. Your choice for the Detector setting (Slow, Fast, or Impulse) determines the
amplitude change rate. The detector first squares the sound signal, then averages it in accordance
with the time-weighting characteristic, and then takes the square root. This results in an ampli-
tude described as rms (root-mean-square).
The Slow and Fast detector responses were originally developed to slow down the movement of
the needle on an electro-mechanical meter, so that the amplitude could be determined. Slow and
Fast detector settings are still useful in modern sound measurement instruments. Slow has a time
constant of 1 second. Fast has a time constant of 1/8th second. The Impulse setting is a non-linear
detector with the rise controlled by a 35 ms time constant followed by a peak hold that has a
decay rate of 2.9 dB/second.
Table C.2 Sound Power Increase
Linear form, non-squared units
Level form
Ration of Value to
Reference
Exponential Form
of Ratio
20•Exponent
1
10
0
0
10
10
1
20
100
10
2
40
200
10
2.3
46
1,000
10
3
60
10,000
10
4
80
100,000
10
5
100
1000,000
10
6
120
dB
10Log
10
P
2
P
0
2
--------
20Log
P
P
0
-----
=
=
p
;
0
20
Pa
=
Содержание 831C-FFT
Страница 1: ...Larson Davis SoundAdvisor Model 831C Sound Level Meter Reference Manual...
Страница 206: ...SoundAdvisor Model 831C A 42 FIGURE A 31 Model 831C with 377C20 Microphone FIGURE A 32 Model 831C with 377C20 Microphone...
Страница 207: ...SoundAdvisor Model 831C A 43 FIGURE A 33 Model 831C with 377C20 Microphone FIGURE A 34 Model 831C with 377C20 Microphone...
Страница 208: ...SoundAdvisor Model 831C A 44 FIGURE A 35 Model 831C with 377C20 Microphone FIGURE A 36 Model 831C with 377C20 Microphone...
Страница 214: ...SoundAdvisor Model 831C A 50 FIGURE A 47 Model 831C with 377C20 Microphone...
Страница 215: ...SoundAdvisor Model 831C A 51 FIGURE A 48 Model 831C with 377C20 Microphone...
Страница 216: ...SoundAdvisor Model 831C A 52 FIGURE A 49 Model 831C with 377C20 Microphone...
Страница 217: ...SoundAdvisor Model 831C A 53 FIGURE A 50 Model 831C with 377C20 Microphone FIGURE A 51 Model 831C with 377C20 Microphone...
Страница 218: ...SoundAdvisor Model 831C A 54 FIGURE A 52 Model 831C with 377C20 Microphone FIGURE A 53 Model 831C with 377C20 Microphone...
Страница 221: ...SoundAdvisor Model 831C A 57 FIGURE A 58 831C With LOWN Mic Set FIGURE A 59 831C With LOWN Mic Set...
Страница 222: ...SoundAdvisor Model 831C A 58 FIGURE A 60 831C With LOWN Mic Set FIGURE A 61 831C With LOWN Mic Set...
Страница 223: ...SoundAdvisor Model 831C A 59 A 10 Declaration of Conformity...
