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In practice, the following applies:
The sound pressure level emitted from audible alarm devices is given for a distance of 1 m from the source of
the noise.
Fig. 42: Example
•
Each time the distance from the source of the noise doubles, the sound pressure level reduces by 50 % (-6
dB).
•
The 6 dB attenuation corresponds to a 50 % reduction in the sound pressure level.
•
At a distance of 10 m from the source of the noise, the sound pressure level is reduced by 20 dB.
An increase in the sound pressure level of 10 dB is perceived as a doubling of the volume
•
(and vice versa).
•
Differences of 3 dB are clearly audible – smaller differences in the sound pressure level are hardly noticed or
only in a direct comparison.
approx. 1,5 m
Fig. 43: Distance from the source of the noise
TI 798960.GB0 / 04.20
72 dB
r1
height
distance
Periphery components for ESSER FACP
92 dB
1 m
Calculating the sound level variation
Determining the sound level variation (∆L) for
sound pressure for acoustic alarm devices:
Unit
r1 = 1 m distance from the source of
the noise
r2 = distance from the source of the
noise
∆L = L2–L1
Level of the distant source:
L2 = L1–20 x log
Sound level variation:
∆L = 20 x log
Value
m
m
dB
r1
(
)
R2
r1
(
)
R2
63
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