sound_filter

strinda

I can't quite get how the filters work. To be more specific, the LowPassfilter takes two parameteres: the cutOff frequency and the bandwidth/resonance. it is the second that I am struggling with. Say the sound spectrum is from 100 Hz to 12000 Hz, I set the filter to cut everything which is lower, than 500 Hz. Now the spectrum should be 500-12000 Hz, why do I need to set the resonance frequeny?

kfrajer

https://p5js.org/reference/#/p5.Filter .....Not clear

https://p5js.org/examples/sound-filter-lowpass.html Demo, worth exploring. Documentation is not clear however...

Kf

jeremydouglass

@strinda: Re: what is the bandwidth/resonance parameter of a sound filter?

Here are explanations taken from non-Processing documentation and discussion:

Low Pass Resonance: As this value increase, the overtones near the cutoff frequency are boosted. The result is that the cutoff frequency is much louder than the rest of the audio being filtered. http://www.acoustica.com/mixcraft/help/mixc/low_pass_cutoff_low_pass_resonance.htm

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an amplitude boost that occurs at the filter's cutoff frequency. The resonance control determines how extreme that "bump" at a certain frequency is. http://forums.musicplayer.com/ubbthreads.php/topics/1087566/What_s_a_resonant_filter

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Resonance effect originates from an artifact in the original cutoff filter used in old hardware synthesizers. It is narrow band of frequencies, near the cutoff level, where the sound is amplified. Today this artifact can be easily avoided, but it is still available though, because it can be used as a special effect. Changes in the cutoff level together with high resonance produces interesting phaser-like effect, which is one of the reasons for the popularity of the TB-303 synthesizer. https://www.image-line.com/support/FLHelp/html/glossary_cutres.htm

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Another concept you should be familiar with is Resonance, which is actually just another filter – a Peak Filter in this case – that boosts frequencies right where the high or low pass filter are starting to cut them, creating some kind of wah-like effect that doesn’t seem to ever get old when applied to analog synths.

http://audio.thedelimagazine.com/production-advice-know-your-filters-low-pass-band-pass-high-pass-resonance/