Ok, so: Unity documentation seems to partially apply also to UE4. Basically you can create objects “Phonon Occlusion Source” “Phonon ReverbSource Settings” “Phonon Spatialization Source” and apply them to a Sound Attenuation:
https://valvesoftware.github.io/steam-audio/downloads.html
To have the environmental and occlusion effects working you should be able to tag the physical objects in the scene to describe the acoustic properties. @Minus_Kelvin: Do you have any example explaining how to achieve this?