Noun

1. The physical quality of a space for performing music.

   Until they discovered the non-contractual concrete slab under the stage floor, everyone at Carnegie Hall wondered, since the renovations, why the acoustics had changed.

2. The science of sounds, teaching their nature, phenomena and laws.

   Acoustics, then, or the science of sound, is a very considerable branch of physics. - Sir John Herschel.

Usage notes

• The science was previously divided by some writers into diacoustics, which explains the properties of sounds coming directly from (sic! Webster) the ear; and catacoustica, which treats of reflected sounds or echoes. This division is now obsolete.