public void run() {
    int repeat = 1;
    try {
      AudioFormat af = new AudioFormat(2000f, // sampleRate
          8, // sampleSizeInBits
          1, // channels
          true, // signed
          false); // bigEndian
      SourceDataLine sdl;
      sdl = AudioSystem.getSourceDataLine(af);
      sdl.open(af);
      sdl.start();

      byte[] buf = new byte[1];
      int step;

      for (int j = 0; j < repeat; j++) {
        step = 5;
        for (int i = 0; i < 2000; i++) {
          buf[0] = ((i % step > 0) ? 32 : (byte) 0);

          if (i % 250 == 0)
            step += 2;
          sdl.write(buf, 0, 1);
        }
        Thread.sleep(200);
      }
      sdl.drain();
      sdl.stop();
      sdl.close();
    } catch (InterruptedException | LineUnavailableException e) {
      e.printStackTrace();
    }
  }