MixSignals.java

    private static byte[] mixSignals(byte[] signal, byte[] noise) {
        ByteBuffer bb = ByteBuffer.wrap(signal);
        bb.order(ByteOrder.LITTLE_ENDIAN);
        ShortBuffer sb = bb.asShortBuffer();
        short[] signalArray = new short[sb.capacity()];
        sb.get(signalArray);

        ByteBuffer bb2 = ByteBuffer.wrap(noise);
        bb.order(ByteOrder.LITTLE_ENDIAN);
        ShortBuffer sb2 = bb2.asShortBuffer();
        short[] noiseArray = new short[sb2.capacity()];
        sb2.get(noiseArray);

        float max = 0;
        for (int i=0;i<signalArray.length;i++){
            if (noiseArray.length>i){
                if (Math.abs(signalArray[i] + noiseArray[i])>max){
                    max = Math.abs(signalArray[i]+noiseArray[i]);
                }
            }
        }
        int a,b,c;

        for (int i=0;i<signalArray.length;i++){
            a = signalArray[i];
            b = noiseArray[i];
            c = Math.round(Short.MAX_VALUE *
                    (a + b) / max);

            if (c>Short.MAX_VALUE){
                c = Short.MAX_VALUE;
            }
            else if(c<Short.MIN_VALUE){
                c = Short.MIN_VALUE;
            }

            signalArray[i] = (short) c;
        }

        byte[] result = new byte[signalArray.length*2];
        ByteBuffer.wrap(result).order(ByteOrder.LITTLE_ENDIAN)
                .asShortBuffer().put(signalArray);
        return result;
    }