Tone, Cutoff, and Resonance: How Digital Filters Shape Acoustic Warmth
An intuitive breakdown of BiquadFilterNode implementations, lowpass curves, and resonance controls in the Web Audio API.
Digital filters are algorithms that modify the frequency content of an audio signal. In the Web Audio API, the BiquadFilterNode provides second-order IIR (Infinite Impulse Response) filtering with minimal CPU overhead.
The master tone control in MURMURFIELD manipulates a low-pass filter cutoff frequency. When set to maximum warmth, high frequencies above 800 Hz are gently attenuated with a 12 dB/octave rolloff. This replicates the acoustic absorption characteristics of thick curtains, wooden bookshelves, or dense foliage.
Conversely, opening the filter allows harmonics up to 16,000 Hz through, imparting sparkle, clarity, and crisp spatial presence. By adjusting tone alongside individual channel gains, users can tailor the acoustic texture to match both their headphone characteristics and their current sensory tolerance.
Hear This Principle in Action
Open the MURMURFIELD soundstage to test this acoustic phenomenon live in your browser.