Audio Filter (High-pass, Low-pass)

How it works

1. Choose an audio file.
2. Pick the filter type, cutoff frequency and slope.
3. Preview the result.
4. Export and download.

Choosing a filter

A high-pass filter lets high frequencies through and removes the low ones: use it for rumble, wind and handling noise. A low-pass filter does the opposite: it softens hiss and harshness, or muffles a sound on purpose. A band-pass keeps one range and removes both ends, which is how telephone and small-radio sounds are made. A notch removes a narrow band and leaves the rest, for a single whistle or hum.

The presets cover the common jobs: remove rumble (80 Hz high-pass), tame hiss, muffle, telephone, small radio and a 50 Hz notch.

Cutoff, slope and Q

The cutoff is where the filter starts to act: the level is 3 dB down exactly at that frequency. For high-pass and low-pass filters the slope sets how steeply the sound falls beyond it: 12, 24 or 48 dB per octave, built from one, two or four cascaded sections. Steeper filters remove more but ring slightly around the cutoff.

Band-pass and notch filters take a width instead, given either as Q (higher is narrower) or in octaves. The response chart updates as you change them, and the chart has a text description for screen readers.

Limits

These are ordinary minimum-phase filters, so they shift the timing of frequencies slightly near the cutoff. That is normal and inaudible for most uses. The cutoff can be set up to 45 percent of the file’s sample rate. Live play uses your browser’s filters with the same design as the export, so what you hear is what you get.

Questions