Re: Filter: definition


Subject: Re: Filter: definition
From: Philippe-Aubert Gauthier (Philippe-Aubert.Gauthier@USherbrooke.ca)
Date: Sun Jun 19 2005 - 09:18:58 EDT


"Amplitude" should be developped a little.

A very math modification would be:

"A processor that modifies complex amplitude in a frequency dependant method."

Here "complex" (that is the gain is complex including the imaginary number) is
introduced to take into account both amplitude and phase modification. So that
a less crude modification would be:

"A processor that modifies an input both amplitude (or gain) and phase in a
frequency dependant method."

The phase is quite important, since many audio filters (for reverberation,
physical models, etc.) are often using "all-pass" filter which introduce no
amplitude modification, only phase changes. Moreover, most of the real time EQ
filters are changing the signals phases.

Bye!

Selon Kevin Austin <kevin.austin@videotron.ca>:

>
> A recent discussion I have had is around a (simplified) definition of a
> filter.
>
> The proposed version (to date) is:
>
> A processor that modifies amplitude in a frequency dependent method.
>
> (A frequency dependent amplifier.)
>
>
>
> Comments / pros - cons / additions etc etc??
>
> Thanks
>
>
> Best
>
> Kevin
>
>

%====================================================================%
% Philippe-Aubert Gauthier, ing. jr , 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) %
% %
% http://www3.sympatico.ca/philippe_aubert_gauthier/acoustics.html %
%====================================================================%



This archive was generated by hypermail 2b27 : Sat Dec 22 2007 - 01:46:09 EST