quad = context.createBiquadFilter();
          biquad.type = filterType;
          biquad.Q.value = 10;
          biquad.gain.value = 10;

          // Create the equivalent IIR Filter node by computing the coefficients
          // of the given biquad filter type.
          let nyquist = sampleRate / 2;
          let coef = createFilter(
              filterType, biquad.frequency.value / nyquist, biquad.Q.value,
              biquad.gain.value);

          let iir = context.createIIRFilter(
              [