I have been experimenting alot with reverb volumes but then I found out how to handle sound groups. How it works: When shooting or walking two sounds are played. One for what you can hear in an pressurized environment and one for the vacuum sound. However they each have a different sound class. When de/pressurizing the player’s environment I simply use “SetAudioGroupVolume” to slowly silence the one sound group while making the other louder and vice versa.
I use standard udk assets as well as modified versions of these sounds: