ue, Math.abs(currentValue));
                    });

                should(
                    maxError,
                    'Max difference between IIR and Biquad on channel ' +
                        channel)
                    .beLessThanOrEqualTo(errorThresholds[channel]);
              }

            })
            .then(() => task.done());
      });

      // Apply an IIRFilter to the given input signal.
      //
      // IIR filter in the time domain is
      //
      //   y[n] = sum(ff[k]*x[n-k