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SC-30
User’s Manual
59
7.7 Definition of functions
7.7.1 Decay curve
Decay Curve Decay of the sound pressure level according to time inside the room
after the source is stopped. This decay can be measured after a real
cut of the continuous emission of a sound source at the room that is
being studied.
7.7.2 Reverberation Time
T
30
Is the time in seconds that is required for the sound pressure level to
decreases 60 dB, calculated on a line from a lineal regression by least
squares approximation of a decay curve measured from a 5 dB level
below the initial level, until a level 35 dB lower than the initial one.
T
20
Is the time in seconds that is required for the sound pressure level to
decreases 60 dB, calculated on a line from a lineal regression by least
squares approximation of a decay curve measured from a 5 dB level
below the initial level, until a level 25 dB lower than the initial one.
The reverberation time of a room is one of the most important
parameters to evaluate its acoustics properties. Its measurement has
important applications on the field of noise control in rooms, Concert
halls and Lecture rooms. The reverberation time measurement is
essential for calculation of the acoustic insulation in buildings and of
building elements, and for the measurement of absorption in
reverberant room.
The reverberation time parameter is defined in the ISO 3382
International Standard.