Rocket Sound Enhancement (RSE) is an Audio Plugin Framework Mod for Kerbal Space Program that offers modders advance sound effects features not available in the base game. It features a robust Layering System for use of multiple sounds just like in other games (eg: FMod).
By itself, RSE only does Sound Limiting and Muffling. You'll need to download a Config Pack Mod in order to have new sounds in your game. If you release a mod that uses RSE, let me know so I can add it here in a list!
Sound Mastering that controls the overall loudness of the game with Adjustable Amount for different dynamics with the "Auto-Limiter" feature or you can tweak your own settings.
Mixer based Audio Muffler with Dedicated channels for Exterior Sounds, Focused Vessel and Interior while ignoring UI sounds like Music.
An Audio Muffler that works on top of the regular muffler that takes into account the Mach Angle, Velocity and Distance of a Vessel with Sonic Booms Effects (provided by a Config Pack via ShipEffects).
Parts with RSE Modules will simulate realistic sound attenuation over distance, comb-filtering, and distortion. Game Events like distant explosions will now sound muffled just like in real life.
AirSim Lite is a version of AirSim that does similar effects without using sound filters.
RSE also adds a more robust Doppler Effect.
Part Modules dedicated for assigning and controlling sound effects for Parts beyond what the regular stock audio can do. Including parts that didn't have any support for sounds before like Rotors, Wheels and Kerbal Jetpacks.