     let gain = context.createGain();
        gain.gain.value = -1;

        // Create the graph.
        for (k = 0; k < nChannels; ++k)
          source[k].connect(merger, 0, k);

        merger.connect(biquad);
        merger.connect(iir);
        iir.connect(gain);
        biquad.connect(context.destination);
        gain.connect(context.destination);

        for (k = 0; k < nChannels; ++k)
          source[k].start();

        context.startRendering()
            .then(function(result) {
             