# How to create a chance that set number of layers might play?

Hi,

First of all, I am very new to FMOD so I apologize if this is an elementary question but…
I am trying to create the following scenario:

I have 4 layers that make up one whole track. When the character is walking around the main world, I want Layer 1 to always be audible, but I also want there a chance to have layer 2, layer 3, and/or layer 4 audible. So after the loop point there may be 1, 2, 3 or 4 total layers being audible.

THEN

When the player enters a puzzle room, I want to reduce the total number of possible audible tracks to 3 instead of 4. I still want layer 1 to always be audible, but I only want a max of 2 other layers to be audible at any given time. This will allow the music to be more mellow when a player is focusing on a puzzle.

I understand how to make the first portion happen, I can simply give layer 2, 3, and 4 some probability that they will play when the character is in the main world. I don’t get how to simply then reduce the total audible layers to 3 max while still allowing there to be a chance for any 2 of the other 3 layers to be audible. Hopefully that makes sense.