# [chuck-users] Using biquad...

Wolfgang Gil wolfgang.gil at gmail.com
Thu Feb 17 19:01:45 EST 2011

```Hey Tom, thanks for answering.
Yeah, i think it would be easier to use a LPF filter.
Anyway, i'll be trying stuff. Later i might release the code to the list.

On Thu, Feb 17, 2011 at 3:33 AM, Tomtom <girodt at gmail.com> wrote:

> Hi
>
> I did something a bit similar recently. My approach was to simply to apply
> a
> decreasing exponential function on an input value to control the gain of a
> sample and simulate distance.
>
> Math.exp(-param * coef) will give you 1 for param=0, and progressively
> decrease
> at a speed controled by coef.
>
> Based on this, I guess all you have to do is to find the proper
> coefficients to
> transform your decreasing parameter into a decreasing frequency for your
> filter.
>
> by the way, if you want to progressively cut the high frequencies, wouldn't
> it
> be simpler to use a LPF filter ?
>
> Tom
>
> Excerpts from Wolfgang Gil's message of jeu. févr. 17 08:02:54 +0100 2011:
> > Hey guys
> >
> > i'm working on a sampler that uses a simple equation system to determine
> > parameters of reverb, volume and pitch filtering. The goal is to emulate
> > 'depth' using the idea that if a sound's source moves away from our ears,
> we
> > will perceive it as quieter and more diffused, with its high-pitch
> content
> > less present.
> >
> > Motivated by this, I started to read about the biquad ugen, but i haven't
> > figured out how to deal with its coefficients so I can make something
> > interesting out of it.
> > My question is, how can i make a high cut filter that gradually reduces
> the
> > high-pitched content of the sound signal's spectrum, based on an input of
> > 0-100?
> > (0 = no filtering, 100 = no high-pitch content)
> >
> > thanks!
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--
Wolfgang Gil
http://www.wolfganggil.com
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