 simple 2-point moving
        // average.  This is rather arbitrary; keep it simple.

        let iir = context.createIIRFilter([0.5, 0.5], [1]);

        // Create the graph
        source.connect(iir);
        iir.connect(context.destination);

        // Rock and roll!
        source.start();

        context.startRendering()
            .then(function(result) {
              let actual = result.getChannelData(0);
              let expected = new Float64Array(testFrames);
              // The filter is 