The slimes attack sound on structures peaks really high, a lot louder than most of the other sound effects. Elevators are also another culprit of this. A difficulty setting much like everyone else already said is needed, especially since in this patch the left side spawns around 8-10 slimes at the same time, making short work of your base within seconds while tanking multiple turrets and one tapping one or even two structures per attack.
For the audio being too loud, for some reason the sound effects feed themselves into a feedback loop which means they double in volume after every single slime attack