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Inverse Square Law for Acoustics

The intensity of a sound is proportional to the square of its sound pressure $ p$ , where pressure is force per unit area

Therefore, the average intensity at distance $ r_{12}$ away from a point source of average-intensity

$\displaystyle I_1\propto\left<\left\vert p_1\right\vert^2\right>$   is$\displaystyle \qquad
\zbox{I(\mathbf{x}_2) = \frac{I_1}{r_{12}^2}}
$

This is a so-called inverse square law.

Remember that far away (in wavelengths) from a finite sound source,

where $ r$ is the distance from the source.

Point-to-Point Spherical Pressure-Wave Simulation:

\epsfig{file=eps/sphericalwavesimulator.eps,width=\textwidth }


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``Computational Acoustic Modeling with Digital Delay'', by Julius O. Smith III, (From Lecture Overheads, Music 420).
Copyright © 2014-03-24 by Julius O. Smith III
Center for Computer Research in Music and Acoustics (CCRMA),   Stanford University
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