Start a one-time sound when app starts

Question

I programmed an intro sound when my app starts, but whenever I click into a new activity, the sound plays again. I only want the sound to play one time at the very beginning, but never again. Here's the relevant code:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    intro = MediaPlayer.create(getApplicationContext(), R.raw.menu);
    intro.start();
}