what is Sabine's formula
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Sabine’s Formula
Sabine’s formula is given by the following:
Sabine's Formula
RT60 is the reverberation time (to drop 60 dB)
V is the volume of the room
c20 is the speed of sound at 20°C (room temperature)
Sa is the total absorption in sabins
The sabin unit has the same dimension as area (e.g. m2). A one square meter surface with an absorption coefficient of 0.75 would be considered 0.75 sabins. The absorption coefficient has a range of 0 to 1, where a coefficient of 0 indicates none of the sound is absorbed, and a coefficient of 1 indicates that 100% of it is absorbed.
Since we know the speed of sound at 20°C is 343 m/s, we can do a little math and reduce the formula to:
Sabine's Formula
(Note that the factor 0.161 has the units seconds per meter; dimensional analysis on the equation will yield a time in seconds as the volume is measured in cubic meters and sabins in square meters).
Let us use this formula to calculate the reverberation time of a fictitious lecture hall. Let us say the hall has a 5-meter tall ceiling, is 20 meters wide and 10 meters deep. Let us also say that the absorption coefficient for the walls, ceiling, and floors is 0.3.
To use Sabine’s Formula, we’ll first need the volume:
Mathematical EquationThe total absorption, in sabins, is the total area times the absorption coefficient. The total area in includes 4 walls, a ceiling, and a floor, which when multiplied by the absorption coefficient gives us the total absorption in sabins:
Math Equations
Sabine’s formula is given by the following:
Sabine's Formula
RT60 is the reverberation time (to drop 60 dB)
V is the volume of the room
c20 is the speed of sound at 20°C (room temperature)
Sa is the total absorption in sabins
The sabin unit has the same dimension as area (e.g. m2). A one square meter surface with an absorption coefficient of 0.75 would be considered 0.75 sabins. The absorption coefficient has a range of 0 to 1, where a coefficient of 0 indicates none of the sound is absorbed, and a coefficient of 1 indicates that 100% of it is absorbed.
Since we know the speed of sound at 20°C is 343 m/s, we can do a little math and reduce the formula to:
Sabine's Formula
(Note that the factor 0.161 has the units seconds per meter; dimensional analysis on the equation will yield a time in seconds as the volume is measured in cubic meters and sabins in square meters).
Let us use this formula to calculate the reverberation time of a fictitious lecture hall. Let us say the hall has a 5-meter tall ceiling, is 20 meters wide and 10 meters deep. Let us also say that the absorption coefficient for the walls, ceiling, and floors is 0.3.
To use Sabine’s Formula, we’ll first need the volume:
Mathematical EquationThe total absorption, in sabins, is the total area times the absorption coefficient. The total area in includes 4 walls, a ceiling, and a floor, which when multiplied by the absorption coefficient gives us the total absorption in sabins:
Math Equations
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