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 Wallace
Clement Sabine
(1868-1919)
Sabine's
Reverberation Formula
Wallace Clement Sabine was a pioneer in architectural
acoustics. A century ago he started experiments in the Fogg
lecture room at Harvard, to investigate the impact of
absorption on the reverberation time. It was on the 29th of
October 1898 that he discovered the type of relation between
these quantities. Sabine derived an expression for the
duration T of the residual sound to decay below the audible
intensity, starting from a 1,000,000 times higher initial
intensity:
T = 0.161 V/A
where V is the room volume in
cubic meters, and A is the total absorption in square meters.
Sabine's reverberation formula has been applied successfully
for many years to determine material absorption coefficients
by means of reverberation rooms. Keeping in mind some
conditions with regard to the sound field diffusion and the
value of A, Sabine's formula is still widely accepted as a
very useful estimation method for the reverberation time in
rooms.
Sabin as Unit of Sound
Absorption
The unit of sound absorption is square meter, referring to the
area of open window. This unit stems from the fact that sound
energy travelling toward an open window in a room will not be
reflected at all, but completely disappear in the open air
outside. The effect would be the same if the open window would
be replaced with 100 % absorbing material of the same
dimensions.
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1 square meter of 100 % absorbing material has an absorption
of 1 square meter of open window. In honor of W.C. Sabine, the
unit of absorption is also named sabin or metric sabin.
However, these units are used not very often. One sabin is the
absorption of one square foot of open window, and one metric
sabin is the absorption of one square meter of open window.
Symphony Hall
The first auditorium that was designed by Sabine, applying his
new insight in acoustics, was the new Boston Music Hall,
currently known as the Symphony
Hall. It was formally opened on October 15, 1900.
Nowadays, it is still considered one of the three finest
concert halls in the world.
Also visit the famous Riverbank
Laboratories.
References
Wallace C. Sabine: Collected Papers on Acoustics. 1993, Trade
Cloth ISBN 0-932146-60-0 Peninsula Publishing, Los Altos, U.
S.. LCCN: 93-085708
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