It seems like it plays at max volume no mater what. It's a nice sound but it's ear piercingly loud.

To clarify, this is the sound that plays when someone else clears a camp you stacked, not the nice sound that plays when a camp is stacked in the first place.

As an example match, 6052962772 when I (the Venomancer) stacked the camp at 15m31s. It doesn't play in the replay apparently though.