see Switching Power Supply

A device under the control of a master device. Often used to refer to synchronised recorders, or digital clocking devices.

The term 'slate' comes from the silent film practice of writing the scene, take and shot numbers with chalk on a slate and holding it up in front of the camera before the action starts, so that the film editor can identify the material. A role now replaced by the 'clapper-board' which adds an audio synchronisation marking facility as well. In an audio context, a slate is a verbal identification recorded just before each take to help identify it subsequently. This is normally achieved by using a talkback microphone routed to the main, group and/or direct outputs of a mixer. The console slate function often mixed a low frequency tone in with the microphone signal to help make locating the start of each take much easier when fast-winding the tape against the playback head. Each slate ident would be heard as a short, steady mid-frequency tone.

A device for removing or attenuating the noise component of a recording or transmission system without pre-conditioning the signal. Most digital noise-reduction systems are of the Single-ended type.

The waveform of a pure sinusoidal tone which has a waveform defined by a mathematical function derived from a classic periodic oscillation, such as the movement of the tip of swinging pendulum. In a musical context, a sine wave contains only a single fundamental frequency, and  no harmonics.

The ratio of nominal or maximum signal level to the residual noise floor, expressed in decibels and often written as S/N.

The route taken by a signal from the input of a system to the output.

An electrical representation of an audio event.

A part of an audio circuit that splits off a proportion of the main signal to be processed in some way. Compressors use a side-chain process to derive a control signals to adjust the main path attenuation.

A high-frequency whistling or lisping sound that affects vocal recordings, due either to poor mic technique or excessive HF equalisation.