The term RECORDING STUDIO APPARATUS is often used to refer to a MIXER, which is a five-letter device used in recording studios. A MIXER is an electronic device that combines multiple audio signals into one or two channels. It is used to adjust the levels, frequency content, and dynamics of the audio signals, as well as to add effects such as reverb and delay. Mixers are essential components of any recording studio setup, allowing engineers to create the desired sound for their recordings.