1.3 Noise development
Sound
A
Structure-borne noise
B
Airborne noise
Structure-borne noise, liquid-borne noise
Mechanical vibrations are induced into bodies, such as machine and
building components as well as into liquids, transferred by them and
radiated out by them at different points as airborne noise.
Airborne noise
Sources of noises (bodies in which vibrations have been induced)
create mechanical vibrations in the air that propagate in wave form and
are audible to the human ear at different levels.
Sound power level and sound pressure level
B
A
A
Source of sound (heat pump)
Emission site
Measured variable: Sound power level L
W
B
Location of incoming sound emission
Immission site
Measured variable: Sound pressure level L
P
Sound power level L
W
This describes the entire sound emissions in all directions emanating
from the heat pump. It is independent of the surrounding conditions
(reflections) and serves as a value for comparison against data from
other heat pumps.
Sound pressure level L
P
The sound pressure level is a measure to assist orientation regarding
the volume of noise perceived by the ear at a specific location. The
sound pressure level is significantly influenced by the distance [from
the object to be assessed] and the surrounding circumstances, i.e. it
is largely dependent on the location where measurements are taken.
The sound pressure level is the variable that is used to assess emis-
sions from individual systems.
Principles
(cont.)
6
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VITOCAL 160-A
1
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Summary of Contents for VITOCAL 160-A
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