- 1). Measure the square footage of the surface you want to test. If you are testing 20 rows of 2-foot by 2-foot panels, with four in each row, then your square footage would be 20 x 2 x 2 x 4, or 320 square feet.
- 2). Activate your testing sound in an empty reverberation room. Then turn the sound off and measure the amount of time it takes the sound to decrease by 60 decibels. Next, bring in the surface you want to test. Activate the sound again and record the new time -- it should be shorter because the surface should have absorbed some of the sound.
- 3). Take the second measurement in time and plug it into this formula (Sabine's Formula):
T = 0.161 x V/A. Wallace Sabine calculated this constant (0.161) in determining this formula.
V is the volume of the room, which you can ascertain by measuring the length, width and height of the floor and walls, if the room is rectangular. Multiply both sides by A and then divide both sides by the time to isolate A, which is the total absorption area.
For example, let's say that the time was 0.8 seconds and the volume of the room is 1,000 cubic feet, using the surface from Step 1.
0.8 = 0.161(1,000)/A
0.8A = 161
A = 201 - 4). Divide A from Step 3 by the area of the sample you tested. The total absorption area tells you the effective absorption of the piece, and you're dividing by the actual area to get the absorption coefficient for that surface. Dividing this by the answer from Step 1 (320), the coefficient for this surface is 0.63.
SHARE
