80 decibels is pretty loud if heard in the air, but I guess that the sound energy could be directed into the ground with minimal escape into the air. Much more research will be required to determine if this will be an efficient way to enhance soil restoration. It doesn't seem very practical for wide scale application.
I wonder if this technique could be used in commercial mushroom production. There shouldn't be a problem if sound-proofing material is applied inside the growing area.