The vertical axis of the low-pass filter controls its resonance, ranging 0 to 24 from bottom to top. The horizontal axis controls the frequency, ranging from 20 hz on the left to 20 khz on the right. Touch and drag anywhere on the device’s touchpad to affect the sound with a combination of the two parameters. If you are actively recording on a loop, touching the Filtr screen causes the effect to automatically reoccur.