A phase locked loop (PLL) is an electronic circuit that has a voltage driven oscillator that is constantly adjusted to match the frequency of an input signal. Operates by comparing the phase of a sample signal, usually the frequency-divided output of the RF oscillator, with a precision fixed reference frequency.

A 1/4" connector found on a lot of audio equipment. The name derives from the old telephone switchboards, which used 1/4" patching cables. Generally available in two varieties, unbalanced or TS, and balanced or TRS, where T stands for tip, R for ring and S for sleeve.

A type of connector originally used by RCA to connect their turntables to amplifiers. The name has stuck, and these kinds of connectors, found on consumer and semi-professional equipment are today still referred to as RCA phono connectors.

A type of synthesis that utilizes computer modeling to analyze and then describe how the physical properties of an instrument affect its tone production. This information can then be written into an algorithm that mimics the output of such an instrument.
(See Algorithm)

Derived from a Greek word that means to press, for the purposes of audio, Piezo microphones are manufactured by coupling a diaphragm to a small layer of crystal. When vibration causes the diaphragm to vibrate and therefore "push" against the crystal, a shift of electrons occurs within the crystal, thus creating a potential difference.

Description of an audio cable that has bare ends rather than a specific type of connector. Often found on wireless microphone applications.

A specific tone frequency outside the human audio range, applied to a transmitter. Used by tone coded squelch systems for receiver squelch control.

A control message within the MIDI specification that changes the pitch of a synthesizer in response to the movement of a lever or pitch bend wheel.

A polar pattern is a plot of a device's sensitivity as a function of the angle around the device. Used to define the characters of microphones and antennas, the plot of the polar pattern will show how well a device will reject sounds from a certain angle (the back of a microphone) or from which angle it is most sensitive.

The ability of an instrument to play more than one note simultaneously. Technically, a piano is 88 note polyphonic, although if the human element were to be taken into consideration, then it would take 8.8 people to fully exploit all 88 notes simultaneous. Likewise, a six-string guitar has a maximum polyphony of six notes.