There are few ways to tackle this:

1 - create an ambient bed of sounds into one audio file that can fool the player into thinking a huge battle is happening but you can control it better.

2 - create a voice limit parameter - so you can only have a few instances of that exact sound call happening at the same time.

3 - use a cool down parameter so you cannot have "machine gun" instances of that sound call one after another.

4 - implement some round robin so each sound call can use a different sound sample and even add in slight volume and pitch variance per each call.

Doing a few or all of these will GREALY help your situation.

One add on to 1st point - this is just a wall paper or foundation for which you could layer actual synced up game sound calls on top of.

for walking you should play one one sound, whenever something is walking and its has the same soumd as other 1000 objects you do if (walking)if (!walkingsound_is_playing) play.walksnd();

I've always wondered how that worked