BRUEL & KJAER 2204 - Page 8

Sound pressure
in bar
mbar
10
,ubar
1
.ubar
o.1
,ubar
o.01
pbar
0.001
,ubar
0.0002
.ubar
Sound level in dB
I
Environmental conditions
1134 dB
- 114 dB
94 dB
74 dB
T
54 dB
I
l
34 dB
I 14 dB
I
1
140
130
120
110
I
T Threshold of pain
T Pneumatic Chipper
T Loud automobile horn (dist. 1m)
Tlnside airliner (DC 6)
-,Inside subway train (New York)
90
-, Inside motor bus
80
100
-, Average traffic on street corner
70
-,Conversational speech
60
-, Typical business office
50
-, Living room, suburban area
40
-,Library -
30
-, Bedroom at night
20
-, Broadcasting studio
10
0
I Threshold of hearing
I
Table 1.1. Some commonly encountered sound pressure levels.
The Detection of Sound.
The human ear is a remarkably sensitive instrument for the detection of
sound waves. Its response to a certain sound pressure level depends however
upon the frequency of the sound. The sensitivity is greatest at 1ooo-6ooo Hz
and falls off both for higher and lower frequencies.
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