A panel in a loudspeaker cabinet designed to reduce back interference noise by isolating the front and rear of the loudspeaker diaphragm.

A sheet of material used to prevent a spill of light in a lantern or in part of a set.

A panel in an auditorium positioned so as to reduce sound reflections and improve the acoustics of the space.

Headset earpiece, microphone and beltpack used for communication and co-ordination of technical departments during a performance. (e.g. "Electrics on cans", "Going off cans"

Many headset systems have multiple channels, enabling different sub-groups to communicate separately.

1) A route leading from one side of the stage to the other, out of the audiences view.2) An electronic filter in a sound system that routes sound of the correct frequency to the correct part of the speaker system. Different speakers handle high frequencies (tweeters) and low frequencies (woofers). Sometimes known as a crossover network.An active crossover splits the signal from the mixing desk into high, mid and low frequencies which are then sent to three separate amplifiers.

A shielded copper cable used for satellite TV, analogue TV, video and some digital connections.Sometimes shortened to 'Coax cable', it consists of an inner solid copper conductor surrounded by a plastic insulator, which is wrapped with a braided copper screen, with an outer protective sheath.There are different connectors used for coaxial cable, including RF connector, threaded F type satellite TV connectors, or locking BNC connectors. There are also different types of coaxial cable, for different purposes, identified by their electrical impedance. 75 Ohm (written as 75Ω) cable is used for video, while 50 Ohm (50Ω) is used for data and radio signals.

An effect caused by the same sound arriving at a given point at slightly different times. This could be the listening position or a microphone. Comb filtering can be reduced in the case of sound from speakers by employing delays, and in the case of microphones by following the three to one rule. See THREE TO ONE RULE and DELAY.

(Capacitor Mic) A microphone that uses the varying capacitance between two plates with a voltage applied across them to convert sound to electrical pulses. Condenser microphones need a power supply to provide the voltage across the plates, which may be provided by a battery within the case of the microphone, or it may be provided from an external phantom power supply. A condenser mic is more sensitive and has a faster reaction to percussive sounds than a Dynamic mic and produces a more even response. See Electret Mic.

A microphone that directly picks up the sound transmitted by a solid material. See Boundary Mic, PCC, PZM.

A colloquial phrase when the speaker believes that there are a lot of unnecessary cues going on. 

It's the job of the lighting or sound designers to ensure the show can be run reliably every night, in discussion with stage management.

If there are lots of cues running in a short period of time, it may be better to simplify them, or make them timed auto-follows, or run them from timecode, to avoid 'death by cues'.

See DIGITAL RECORDING

A tape-recording noise reduction process.

Connecting items of equipment together by linking from one to the next in a chain. Used for connecting demux boxes to dimmers etc.

(Digital Compact Cassette) Manufactured by Philips in the Netherlands, this format was supposed to be the successor to the compact cassette, but Mini Disk won the marketing war. DCC was discontinued for mass market use in 1996. See DIGITAL RECORDING.

Acronym for Electronic Dance Music. Repetitive beats and an awesome light show.

Electrical safety requirement that metal parts of electrical equipment are connected to a common earth or ground point so that in the event of a fault, excess current can be carried away, causing the fuse to blow. Known in the USA as Ground.

Some sound problems (such as hums) can be cured by altering the earthing / grounding arrangements of the system, but this should never involve removing the earth connections to equipment, only by adding an earth connection where none exists, or by adjusting the way audio cables are wired. Seek professional advice to avoid safety problems.

when you catch a real fade.

A vertical slider which is used to remotely set the level of a lighting or sound channel.

A snap fade is an instant change. A slow fade could be anything from 5 seconds to a few minutes (or even more, for a naturalistic sunset lighting effect). A quick fade is a couple of seconds long.

when you catch a glizzy

Ubiquitous sticky cloth tape. Most common widths are .5 inch for marking out areas and 2 inch (usually black) for everything else. Used for temporarily securing almost anything. Should not be used on coiled cables or equipment. Originally known as Gaffer's Tape, from the Gaffer (Master Electrician) on a film set. Also known as Duct Tape.See also PVC Tape.

1) The level of amplification given to a signal or of a system.2) A control of the amount of pre-amplification given to a sound signal on its way into a mixer. Particularly important for microphone inputs - a quiet vocal will require a lot of gain, a loud singer less so.

As audio connectors are usually referred to as male or female versions, a gender changer is used to change a male connector to a female etc. 

A headphone and microphone combination used in such communications systems with a beltpack.See also CANS.

a thing that you stick it to your xbox one

Head-Related Transfer Function. A way of measuring how each pair of human ears responds to sound, based on the size and shape of the head, ears, ear canal, density of the head, and the size and shape of nasal and oral cavities.

Music heard by the audience in a non-musical performance, either as background atmosphere as underscore, or between scenes or to set the mood.

Incidental music is not heard by the characters in the play, so is non-diegetic.

An array of jack sockets ('jills'), providing connections to equipment/outlets etc. A patch panel.

An adaptor from one type of electrical connector to another. For example, a 13 - 15A jumper has a 13A plug and a 15A socket at either end of a short cable. Also applicable to sound cables.

Stereo jacks have three connections - tip, ring and sleeve.

A section on a lighting or other technical layout plan, which denotes what the symbols on the plan refer to. Although many symbols are standardised, there are variations, and to avoid confusion (or errors) when rigging and laying out equipment, a key is essential to ensure the requirements of the design are correctly interpreted. 

To switch off (a light/sound effect); to strike/remove (a prop)

A Lady and the Tramp moment occurs when two people clearing and coiling LX or sound cables end up both coiling the same one. Named after the Disney classic animation where two dogs end up eating the same piece of spaghetti.

In digital live sound systems there are tiny time delays due to the processing time required to convert sound from analogue to digital and back again. This time period is known as the LATENCY of the system.

Originally, a mic worn around the neck on a string. Now applies to a small 'tieclip' microphone. These microphones are used for TV and also in musical productions requiring the amplification to be 'invisible'. The mic is worn in clothing, in hair / wigs, over the ear or on the face (heavily made-up).

Non-magnetic plastic tape used to begin and end sound tapes and to separate cues on tape. Clear leader tape is used to activate the automatic stop on some playback machines. Leader tape is available in a variety of colours.

1) The setting of a light or sound control channel. On a lighting desk, levels range from 0% to 100% (also known as FULL). On a sound desk, the bottom of the fader is ∞ (infinity) and the top may be +20. The fader is designed to be operated at it's optimal position which is labelled 0dB. The decibel (dB) scale is a measure of sound intensity. 2) A platform used to change the height of an actor. Interesting dynamics between different characters in the play can be explored using various levels. 

eg on a 8 x 8 matrix, each of the 8 group outputs from the channels can be routed to any or all of the matrix outputs.

Set of outputs on a mixing desk which allows the user to preset a number of output configurations.

On a lighting desk the PRESET MASTER allows the control of a section of the desk independently from the rest.