Audio Decay Time

01 Mar 1998

NOTE: THIS DOCUMENT IS OBSOLETE, PLEASE CHECK THE NEW VERSION: "Mathematics of the Discrete Fourier Transform (DFT), with Audio Applications --- Second Edition", by Julius O. Smith III, W3K Publishing, 2007, ISBN 978-0-9745607-4-8. - Copyright © 2017-09-28 by Julius O. Smith III - Center for Computer Research in Music and Acoustics (CCRMA), Stanford University

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Audio Decay Time ( $t_{60}$ )

In audio, a decay by is too small to be considered a practical ''decay time.'' In architectural acoustics (which includes the design of concert halls), a more commonly used measure of decay is '' $t_{60}$ '', which is defined as the time to decay by dB.^5.5 That is, $t_{60}$ is obtained by solving the equation

Using the definition of the exponential $$a(t) = A e^{-t/\$ , we find

Thus, $t_{60}$ is about seven time constants. See where $t_{60}$ is marked on Fig. 5.5 compared with $$\$ .
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GUIDE: Mathematics of the Discrete Fourier Transform (DFT) - Julius O. Smith III. Audio Decay Time

Audio Decay Time ()

Audio Decay Time ( $t_{60}$ )