# DSP frequencies filter

**URL:** <https://qa.fmod.com/t/dsp-frequencies-filter/21580>\
**Category:** FMOD Engine\
**Created:** [May 4, 2024, 11:24am UTC](https://qa.fmod.com/t/dsp-frequencies-filter/21580 "2024-05-04T11:24:35Z")\
**Posts on this page:** 1\
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**Author:** ![Leah\_FMOD](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/leah_fmod/32/3685_2.png) [@Leah\_FMOD](https://qa.fmod.com/u/Leah_FMOD)\
**Post date:** [May 9, 2024, 3:17am UTC](https://qa.fmod.com/t/dsp-frequencies-filter/21580/2 "2024-05-09T03:17:20Z")

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Unfortunately, what you’re asking for falls outside the scope of support. However, I can definitely point you in the direction of some resources.

For filtering, the “Filtering” chapters of the [Digital Signals Theory book](https://brianmcfee.net/dstbook-site/content/intro.html) by Brian McFee is a good start, and contains Python examples of a number of filter types. You may also want to look into Linkwitz-Riley filters, which will allow you to split a signal into frequency bands - from there, you can process the result and then sum the individual bands together to produce the output.

As for denoising, you can use the new [Multiband Dynamics effect](https://www.fmod.com/docs/2.03/api/effects-reference.html#multiband-dynamics) included in FMOD 2.03 as a gate with the downward expansion mode. If you’re wanting to write your own denoiser, an easy option would probably be to use a phase vocoder algorithm, which you can use to zero out specific frequencies with magnitudes below a threshold. This is often done using a reference or sidechained “noise” signal.

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