createBiquadFilter

createBiquadFilter is a method of the Web Audio API's AudioContext that creates a BiquadFilterNode. This node implements a digital biquad filter used for real-time audio processing and tone shaping. The filter can be configured as different filter types to affect specific frequency ranges.

A BiquadFilterNode can operate as different filter types: lowpass, highpass, bandpass, lowshelf, highshelf, peaking, notch, and allpass.

Default values: type is lowpass, frequency 350 Hz, Q 1, and gain 0 dB.

Usage can be described by creating an AudioContext, calling createBiquadFilter, setting its properties, and connecting it to other nodes in the graph. For example: var ctx = new AudioContext(); var filter = ctx.createBiquadFilter(); filter.type = 'lowpass'; filter.frequency.value = 1000; source.connect(filter); filter.connect(ctx.destination);

Parameters include frequency (Hz), Q (dimensionless), and gain (dB). Note that gain is used by shelf and peaking filters; other types ignore gain. The frequency and Q control the position and bandwidth of the filter, while the type selects the overall shape of the response.

Automation and scheduling: the frequency, Q, and gain parameters can be automated with methods such as setValueAtTime, linearRampToValueAtTime, or exponentialRampToValueAtTime to vary the filter response over time.

Applications and compatibility: BiquadFilterNode is commonly used for equalization, tone control, and general filtering in audio software. It is widely supported in modern browsers, including Chrome, Edge, Firefox, and Safari.