## Biquad filter

The **biquad~** object is a biquadratic filter. In technical terms, that’s a second-order IIR filter with two poles and two zeros; in practical terms, it’s a versatile filter that can have a wide variety of characteristics—lowpass, hipass, bandpass, notch, shelf, etc.—depending on the values of the coefficients in the filtering equation. But unless you’re a trained electrical engineer, you probably don’t know exactly how the coefficient values correspond to particular filtering characteristics.