Audible beats can be attributed to :
A. constructive interference.
Constructive interference happened when two waves meet in such a way that their crests lined up together.
Increase
Unemployment could increase because robots could be used in place of human labor, which in turn means people lose their jobs.
Parasitism relationship, where one takes something (leeches off) the other
There is no info for anyone to answer this
Erosion etc. if it's specific then rain and weathering maybe
