             let iir1Data = result.getChannelData(0);
              let iir2Data = result.getChannelData(1);

              // Threshold isn't exactly zero because the arithmetic is done
              // differently between the IIRFilterNode and the BiquadFilterNode.
              should(
                  iir2Data,
                  'Output of IIR filter with unnormalized coefficients')
                  .beCloseToArray(iir1Data, {absoluteThreshold: 2.1958e-38});
            })
            .then(() => task