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comb filter effect

Comb filter effects occur in acoustics and are caused by the superposition of time-delayed signals. Time-delayed signals occur when one signal arrives directly, and others arrive at a microphone or the listener via reflections from walls, floors, or ceilings. The direct signal arrives before the refexion signals in time, causing the signals to influence each other. This can be expressed as an emphasis or attenuation of the sound.

Since the reflection travel times are constant, the phase positions shift with frequency. A lower frequency could thus be in phase with the directly incoming frequency, while a higher frequency could compensate for part of the directly incoming frequency and thus reduce it in level.

Transit time differences in the comb filter effect

Transit time differences in the comb filter effect

If the amplitudes of the direct and reflected sound are equal and have the same phase, the levels sum up to twice the amplitude value; if they have opposite phase, they cancel each other out.

Expression of the comb filter effect at different locations

Expression of the comb filter effect at different locations

The summation and subtraction of different frequencies results in a frequency spectrum comparable to that of a comb filter, hence the name comb filter effect.

Informations:
Englisch: comb filter effect
Updated at: 15.01.2015
#Words: 190
Links: filter, acoustics, signal, microphone (Mic), vertical interconnect access (PCB) (via)
Translations: DE
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