Eurapo Prisma PV - 9 Noise Levels; Sound Power; Sound Pressure in a Closed Environment

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9. NOISE LEVELS
9.1 SOUND POWER
The acoustic emission characteristics of any noise source is defined as its «sound power» (SWL). This typical measurement
indicates the total radiated energy which does not vary for a given noise source; that is, it does not depend on the observer,
location, distance or any other factor which is not part of the source.
9.2 SOUND PRESSURE IN A CLOSED ENVIRONMENT
The perceived noise radiated from a sound source is something quite different: noise perception is indicated by its «sound
pressure» (SPL). Even though it is caused by the emission of sound energy, it greatly depends on the environment through
which the sound travels, on the distance from the source and on all other circumstances that are not directly related to the
primary noise source.
Besides the distance from the source, the most important factor that influences the «sound pressure» (and, as a result, the
perceived noise) in a closed environment is the amount of sound energy reflected off surfaces that have a greater or lesser
reflection capacity: it depends, therefore, on the re-transmission of sound energy (power) acting upon reflecting surfaces.
Covering the walls with sound absorbing material (i.e. material with a low sound reflecting capacity) is the most effective way
to reduce the noise level in a closed environment. The following values indicate the sound pressure emitted by the fan coils.
By using the EURAPO software for selection it is possible to calculate the new sound pressure level obtained by changing the
parameters: room volume, distance from the noise source and reverberation time.
The reverberation time measures the sound characteristics of a room: it increases as the room dimensions increase and
decreases as the sound absorption capacity of the structure increases.