1680s, "science of sound," from acoustic (also see -ics). Meaning "acoustic properties" of a building, etc., attested from 1885.
acoustics a·cous·tics (ə-kōō'stĭks)n. The scientific study of sound, especially of its generation, transmission, and reception.
(Used with a singular verb) The scientific study of sound and its transmission.
(Used with a plural verb) The total effect of sound, especially as produced in an enclosed space.