o multiple channels
        let merger = context.createChannelMerger(2);

        // Create the graph, filtering the source through two biquads.
        source.connect(biquad1);
        biquad1.connect(biquad2);
        biquad2.connect(merger, 0, 0);

        source.connect(iir);
        iir.connect(merger, 0, 1);

        merger.connect(context.destination);

        // Now filter the source through the IIR filter.
        let y = iirFilter(buffer.getChannelData(0), cascade.ff, cascade.fb);

        // Roc