Audio Acquisition Terms
AGC (automatic gain control) A circuit on most camcorders that automatically adjusts a microphone's gain (volume) to match environmental sound levels.
ambient sound (ambience) background audio representative of a given environment. On-camera dialog might be primary sound; traffic noise and refrigerator hum would be ambient.
audio mixer The piece of equipment used to gather, mix and amplify sounds from multiple microphones and send the signal on to its destination.
bidirectional Microphone pickup pattern whereby sound is absorbed equally from two sides only. [See omnidirectional, unidirectional.]
boom A device for suspending a microphone above and in front of a performer.
cardioid A microphone that picks up sound in a heart-shaped pattern.
condenser mike A high-quality mike whose transducer consists of a diaphragm, backplate and capacitor.
dynamic mike A rugged microphone whose transducer consists of a diaphragm connected to a moveable coil.
electret condenser Microphone type incorporating a pre-charged element, eliminating need for bulky power sources. [See condenser.]
handheld mike A microphone that a person holds to speak or sing into. Also called a stick mike.
hiss Interference in audio recording, result of circuit noise from a playback recorder's amplifiers or from a tape's residual magnetism.
impedance Opposition to the flow of an audio signal in a microphone and its connecting cable.
lavalier A small mike that can be worn around the neck on a cord or clipped to a shirt.
mike (also "mic") Common abbreviation for microphone.
mix Combining sound sources to achieve a desired program audio balance. Finished output may be mono, stereo or surround.
noise Unwanted sound or static in an audio signal.
omnidirectional A microphone that picks up sound from all directions. [See bidirectional, unidirectional.]
phone plug Sturdy male connector compatible with audio accessories, particularly for microphone and headphone cables. Frequently referred to by their sizes, usually 1/4-inch and 1/8-inch.
pickup pattern Defines a microphone's response to sounds arriving from various directions or angles. [See omnidirectional, unidirectional.]
PZM (pressure zone microphone) Small, sensitive condenser mike, usually attached to a metal backing plate. Senses air pressure changes in tiny gap between mike element and plate. Trademark of Crown International. Generically, "boundary microphone" is preferred.
signal-to-noise ratio (S/N) Relationship between signal strength and a medium's inherent noise. Audio S/N specifies amount of background tape hiss present with low- or no-volume recordings. Higher figures represent a cleaner signal. Usually cited in decibels (dB).
sound bite Any short audio segment for use in an edited program - usually a highlight taken from an interview.
three-to-one rule A microphone placement principle that states if two mikes must be side by side, there should be three times the distance between them that there is between the mikes and the people using them.
unidirectional Highly selective microphone pickup pattern, rejects sound coming from behind while absorbing that from in front. [See bidirectional, omnidirectional.]
wild sound Nonsynchronous audio recorded independent of picture (rain on roof, five o'clock whistle) -- often captured with separate audio recorder.
windscreen Sponge-like microphone shield, thwarts undesirable noise from wind and rapid mike movement.
XLR (ground-left-right) Three-pin plug for three-conductor "balanced" audio cable, employed with high-quality microphones, mixers and other professional audio equipment.