How to change the music when player's pokemon are low hp?

[pokemonmasteraaron]

I think this is self explanitory, and would be easier than adding a lowhp sound effect, as there should only be 2 or 3 lines of code, all in the same place.
Can someone hel me do this?
Or atleast tell me were I could put the code?

 

[FL]

Search for 'hpzone' in PokeBattle_ActualScene. Make a similar thing (when zone is/isn't equals 2) to start/stop the sound.

 

[TACHAN]

I also want to put it in my game, but I do not know do it.