a simple 2-point moving average of an impulse, so
              // the first two values are non-zero and the rest are zero.
              expected[0] = 0.5;
              expected[1] = 0.5;
              should(actual, 'IIR 1-zero output').beCloseToArray(expected, {
                absoluteThreshold: 0
              });
            })
            .then(() => task.done());
      });

      audit.define('one-pole', (task, should) => {
        // Create a simple 1-pole filter and compare with the expected outp