Flat

A musical symbol denoting the lowering in pitch of a note by a semitone or half step. The term is also used colloquially to describe a note played or sung at too low a pitch. Opposite of sharp. See: Intonation.

The term flat is used differently in reference to electronic and electroacoustic devices. Here the frequency response of a system, such as an amplifier, is said to be flat for the range of frequencies over which the gain of the system is equal. The importance of flat response is that all frequencies are reproduced equally well without any being under- or over-emphasized, as is the case with resonance (see also resonance curve, resonator).

The frequency response of the ear is not flat (see equal loudness contours), nor is that of rooms or other enclosed spaces (see eigenton). However, flat response is a desirable characteristic of magnetic tape, loudspeakers, amplifiers and microphones. Bass and treble controls on an amplifier may be used to adjust the frequency response according to the ear's sensitivity (see equalization) .

In studio recording, a flat is a movable baffle covered with an insulating material and used to separate various sound sources.