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Comb Filtering

An acoustic interference artifact created when direct sound combines with a delayed reflection.

By roomtreatment.diy editorial team ·

Comb filtering is a destructive phase cancellation pattern occurring when a sound wave mixes with its delayed copy. The resulting frequency spectrum displays regularly spaced series of peaks and deep nulls resembling comb teeth.

The formula

fnull=1,3,5...2Δtf_{\text{null}} = \frac{1, 3, 5...}{2 \Delta t}

How it works

Comb filtering commonly happens when unabsorbed side-wall reflections reach the mixing position or when two microphones capture the same sound source at different distances.

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References

  1. Everest, F. A. (2015). Master Handbook of Acoustics

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