Acouticist. The term is very rarely used. Sound engineer might be used more often.
someone who studies sound and it's properties is a Audiologist
A scientist that studies bats is called a chiropterologist.
Audiologist
A physicist.
A scientist who studies mollusks is called a teuthologist.
A scientist is someone who studies science.
The name of a scientist that studies sports is called a sports scientist.
A scientist who studies butterflies and moths is called a lepidopterist.
An Entemologist
A scientist who studies animals is called a zoologist.
A scientist that studies fungi is called a mycologist.
A scientist who studies insects is called an "entomologist".