Re: Reverb and Cancellation


Subject: Re: Reverb and Cancellation
From: Philippe-Aubert Gauthier (Philippe-Aubert.Gauthier@USherbrooke.ca)
Date: Mon Aug 09 2004 - 09:58:15 EDT


Assuming that by "phase cancellation" you mean destructive interference (like a
sine wave plus a similar sine wave out of phase gives zero), the answer is yes:
Some strong delays (like early reflections) will cause some dips in your
frequency spectrum. Its the same for reverberation, but in this case, the
reflection arrival are so dense (in time) that the frequency spectrum
alteration is more smooth. You will get a phase cancellation (partial
destructive interference) when your delay is corresponding to half a period of
the killed frequency.

This is rougly speaking. You can also have similar physical explanation if you
take a modal perspective on room dynamics.

Selon Jay Smalridge <inadaze@mac.com>:

> Hi all,
> I was wondering if anyone knew if reverberation in a room or a delay in the
> signal creates phase cancellation? I guess the room would have to be small
> to make any significant change, but does the principle still exist?
>
> Thanks
> Jay
>
>

%====================================================================%
% Philippe-Aubert Gauthier, B.Ing, M.Sc. %
% Étudiant au doctorat en reproduction de champs acoustiques %
% %
% GAUS (Groupe d'Acoustique et de vibrations de l'Université de %
% [ Sherbrooke) %
% CIRMMT (Centre for Interdisciplinary research in Music, Media %
% [ and Technology) %
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% http://www3.sympatico.ca/philippe_aubert_gauthier/acoustics.html %
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