Code to synthesize a 16 bit linear PCM sine wave (tone).

PCM_SineWave.java

float freq = 440f;
    float sRate = 8000f;
    int numSamples = (int) (sRate * SINE_WAVE_DUR_SECS);
    float[] rawSamples = new float[numSamples];
    for (int i = 0; i < numSamples; ++i) {
      rawSamples[i] = (float) Math.sin(2.0 * Math.PI * i / (sRate / freq));
    }
    sineWaveSamples = new byte[numSamples * 2];
    int j = 0;
    for (float sample : rawSamples) {
      final short scaledSample = (short) (sample * 32767);
      sineWaveSamples[j++] = (byte) (scaledSample & 0x00ff);
      sineWaveSamples[j++] = (byte) ((scaledSample & 0xff00) >>> 8);
    }