The idea: to create an ambience, you cast an event rain around the player (2d or 3d - depends on your implementation of game world).

When a drop of the "event rain" event hits something, it creates a short-lived decorative object. For example, on the lava it will be a bubble or gurgling sound, on the grass it would be a cicade chirip or a butterfly flying away, on a tree it would be a leaves rustling or a bird warble... And so on.

The thing is, you have one, centralized and easily controlled, source of all your ambient events. You can easily control the resource consumption, since all the events happen only around the player, and you are the one who controls this zone's radius!

Plus, this could create a great, non-repetitive, dynamic ambience without the need to create a huge, complex "athmospheric" MP3s.

What do you think about this idea of mine?