The idea to listen for
A filter envelope changes the filter over the life of a note. With a low-pass filter, a quick opening and closing gesture can make a stable oscillator feel plucked. The underlying amplitude may continue after the bright onset has faded. This separation lets you shape definition without making the entire note louder. Cutoff starting position, modulation amount and envelope shape all affect the result.
Set up a fair comparison
Try the exercise
- Begin with a static filter that leaves a rounded body. Add a small envelope movement while leaving the amplitude envelope unchanged.
- Compare a quick filter decay and a slower one. Listen to how long the upper detail remains after each onset.
- Reduce modulation depth until the gesture complements the rhythm. Check the lowest and highest notes in the phrase.
If the result is not working
If the effect is inaudible, the oscillator may contain little energy above the current cutoff. If every note sounds sharp, lower the envelope depth or starting cutoff rather than shortening the amplitude indiscriminately.
A closer listening check
Can you hear a brief opening followed by a stable darker body? That distinction is especially useful for a bass that needs articulation while remaining restrained beneath a cold atmospheric layer.
Technical background
- Ableton Learning Synths — Interactive synthesis fundamentals.
- MDN: OscillatorNode — Waveform and oscillator behavior in Web Audio.
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