- Waves of sound travel with a velocity of approximately
*c*= 345 meters / second in air. - The propagation of sound over a distance
*d*thus involves a time delay of*d*/c seconds. - A digital delay line (Fig. 9) defined by the difference equation

(where the input signal for*n*< 0 and*y*[*n*] is the output signal) can be interpreted as a physical model of traveling-wave propagation over a distance*d*, where*M*=*f*_{s}*d*/*c*is the number of discrete-time samples corresponding to a distance*d*at a sample rate*f*_{s}. - Assuming the input to the delay line is a traveling-wave variable at time
*n T*, where*T*is the sampling period, the output of the delay line represents a time-delayed version of that wave value. - The delay-line implements lossless, plane-wave propagation. If we wish to simulate spherical-wave propagation of pressure, the output would be scaled by a factor 1/
*d*.

©2004-2017 McGill University. All Rights Reserved. Maintained by Gary P. Scavone. |