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Webster 1828 Edition

Noun.

That part of acoustics or the doctrine of sounds, which treats of reflected sounds. But the distinction is deemed of little use.

catacoustics ‎(uncountable)

(archaic) The science which studies reflected sound.
- 1853, J. B. Upham, "A Consideration of some of the Phenomena and Laws of Sound, and their application in the Construction of Buildings designed especially for Musical Effect," American Journal of Science, vol. 15, p. 224:
  The subject of Catacoustics, or the doctrine of reflected sound, is, perhaps, the most unsatisfactory in its results of any branch of physical science.