How do I switch sound?

[C4PRO]

Hi, I'm making a app where you press a button and a beeping noise happens between 15 - 45 seconds. then a explosion sound go off (like a bomb). I don't know how to switch the beeping noise to the explosion noise. Can anyone help me with this?

[nivram]

Set Alterable Value A to 15. Set Alterable Value B to 1
Every 1 second subtract 1 from Alterable Value A.

Alterable Value A = 0
+Alterable Value B = 1
+Only one action when event loops
Stop Sample "beep"
Start Sample "explosion

Marv