- A term used to define systems incorporating sound control.
- All that pertains to and is correlated with sound, but not having its physical properties or characteristics. Terms with acoustical should relate to units, measurement, materials, and devices. This contrasts with acoustic, which pertains to the detection, production, transmission, reception, control, processing, and study of sound, in addition to all phenomena arising from the effects of sound. Nonetheless, even in technical usage acoustic and acoustical are mostly used synonymously.