How do I start a sound as the player gets closer

So I have this explosive mine and I want it to beep as the player gets closer to it

Here is a little demo I made for another post:

dropbox.com/s/0ffgp2436nwxymt/distanceVolume2.capx

Here is a little demo I made for another post:

https://www.dropbox.com/s/0ffgp2436nwxymt/distanceVolume2.capx?dl=0

How did u add the local variable?

Exactly the same way you add global variables :)

Just select an event and press V. Or add a global variable and move it inside an event.