In audio, a decay by
(one time-constant) is not enough to become inaudible, unless
the starting amplitude was extremely small.
In architectural acoustics (which includes the design of
concert halls [4]), a more commonly used measure of decay is ``
''
(or T60), which is defined as the
time to decay by
dB.4.7That is,
is obtained by solving the equation
Using the definition of the exponential
Thus,