how to stop music when leave the application on phone ?

[espace]

hi,

I have this piece of code to play my ambiance music. these function is on the top of my state to be accessible trough all the different states.

Everything works fine expect when i leave the game on my phone. The music is still playing.

What's the syntax for the  event : to say "we leave the game" then stop the music with music_ambiance.pause(); ?

var music_ambiance=new Audio('sounds/music_ambiance/mus.ogg');

music_ambiance.loop=true;
music_ambiance.volume=0.20;

music_ambiance.play();
//for pause 
//music_ambiance.pause();

music_ambiance_mute=function(){
  music_ambiance.volume=0;
};

music_ambiance_activate=function(){
  music_ambiance.volume=0.20;
};