Autowah is a post-effect. It processes the audio signal coming from any Source blocks connected to it by applying a ‘low-pass’ filter. The frequency of the filter is set in response to the volume of the audio signal. As this frequency sweeps up and down it creates the “wah” sound associated with a wah-wah pedal.

In the Autowah’s options, ‘Frequency’ is the lowest starting point for the filter sweep, ‘Range’ determines how wide the sweep is, and ‘Attack’ & ‘Release’ determine how sensitively the filter follows the incoming audio signal.

Outside of BlokDust, an Autowah may also be known as an envelope filter or envelope follower, among other names.

BlokDust’s Autowah uses the autowah component in the Tone.js framework. The Tone.js autowah is influenced by Tuna.js, an effects library for the Web Audio API.