PhysSound Open Source
Here's the license
Here's the download from the author
Optimization
Optimization up ~30 fps in heavy scene. Changed only PhysSoundObject.cs script.
PhysSound without optimization https://youtu.be/ESEi2VGAPBQ
PhysSound with optimization https://youtu.be/EWA-PtrIAkQ
PhysSound optimization NotInSoundZone https://youtu.be/aN22MnHVCW8