Now, we all love to see a city getting exploded in powder toy, but what lacks is a big boom and the sound of buildings on fire and stone falling to the ground.

So I thought that maybe every time particles had certain interactions, each particle would has a chance of playing a very small and short sound file. So a small number of stone particles hitting metal would make a small group of "Stone hitting metal" sounds.
Or, if they were settling into a pile, stone hitting another stone lightly on a mound sound. A fire particle, would have a randomized chance also of playing sound file, perhaps if it is something burning it makes a crackle, and if it is just fire in the air it makes a fire whoosh sound.
A particle exploding may play a small boom, in a group making a big boom, and stones falling in water make a splash. Perhaps what sound each element plays could, rather than being manually selected, be chosen by what code each element has?

Proof that this idea could work: http://thisissand.com/ It's been done before.