Page 202 - Master Handbook of Acoustics

entire response curve can be sketched as the phase of the two waves alternates between the in-phase
and the phase-opposition condition through the spectrum.
An important point to observe is that the 1/(2t) expression above gives a null at 500 Hz, which

robs energy from any distributed signal subject to that delay. A music or speech signal passing
through a system having a 1-msec delay will have important components removed or reduced. This is
comb-filter distortion.
If the mathematics of the 1/t and the 1/(2t) functions seem too laborious, Figs. 10-14 and 10-15 are
included as graphical solutions.

FIGURE 10-14 The effect of amplitude ratios on comb-filter peak height and null depth.