private static void init() {
        try {
            // 44,100 samples per second, 16-bit audio, mono, signed PCM, little Endian
            AudioFormat format = new AudioFormat((float) SAMPLE_RATE, BITS_PER_SAMPLE, 1, true, false);
            DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

            line = (SourceDataLine) AudioSystem.getLine(info);
            line.open(format, SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE);
            
            // the internal buffer is a fraction of the actual buffer size, this choice is arbitrary
            // it gets divided because we can't expect the buffered data to line up exactly with when
            // the sound card decides to push out its samples.
            buffer = new byte[SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE/3];
        } catch (Exception e) {
            System.out.println(e.getMessage());
            System.exit(1);
        }

        // no sound gets made before this call
        line.start();
    }