Class B is opposite to class A in that the current in a specific output flows for one half cycle. In other words, both output devices are never on simultaneously. This system allows for much better efficiency, but displays poor linearity around the crossover region, since it takes time to turn one device off and the other device on.

A type of amplifier design where the output device is always on for both parts of a complete sinusoidal cycle. Class A is the most inefficient of all power amplifier designs, averaging only around 20%. Because of this, class A amplifiers are large, heavy and run very hot, due to the amplifier constantly operating at full power.

Used in reference to headphones and means "around the ear." Can be combined with semi open, closed and open back designs.
(See Supra-Aural)

The particular frequency to which a given filter-band in an equalizer is tuned to. Parametric equalizers are able to sweep the center frequency, providing a greater degree of flexibility to the EQ, while graphic EQ's have a number of fixed center frequencies.

A modulated RF signal. That is, one which is carrying audio or other information. FM and AM radio employ two carrier signals but modify them in different ways. FM synthesis uses a carrier as part of the algorithm for generating sound.

The portion of a microphone that converts acoustic energy to electrical energy. Often includes shock mounts, acoustic isolators, protective covers and electronic circuitry in addition to the basic transducer. Also called an element.

A subset of the standard .wav audio file format commonly used by PC's. The specification restricts what kind of audio data can be carried, along with extra data that provides information on the title, date, time etc. of the audio file.

A type of filter in which the cut-off slope is very steep, almost resembling a wall. Sometimes used in converters to remove source material above the Nyquist frequency, but the negative results of phasing and attenuation of bands near the center frequency make them unusable for higher end applications.

Also referred to as house or video sync. Derived from video editing where video decks and cameras needed to proceed from one frame to other with absolute synchronization, the term is now finding use amongst audio professionals as they find the need for their digital workstations to lock to picture when working on film or video projects.

In digital audio, the term is used to define the number of bits a digital device uses to process audio. While sampling frequency determines the outer frequency limits that a piece of hardware is capable of processing, bit depth refers to the dynamic range that can be captured during recording.