Audio-Visual Glossary



Z: Symbol for impedance. (See IMPEDANCE.)


ZAP: To eradicate (erase) all or part of a program or database, or any computer stored information.


ZEN DRUM: This is a very sophisticated percussion instrument - all computerised. It is worn somewhat like an electric guitar, and it creates a tremendous number of different percussion sounds by tapping its black sensor knobs.


ZENITH: The front to back tilt of an audio tape recorder’s record and playback heads. (Compare AZIMUTH.)


ZEPPELIN: A “zeppelin” is a tubular covering for a microphone that surrounds the microphone on all sides. It is usually made of a flexible plastic mesh frame covered with a porous fabric. The zeppelin is used mainly for recording film or video sound on location to protect the microphone and to block wind from hitting the microphone. It is important that microphones be shielded from the wind, otherwise the wind will hit the microphone element and produce a horrible amount of unwanted rumbling noise. Wind can even damage a microphone, so it’s important that it is protected. (See WINDJAMMER.)


ZERO CROSSING: If two sounds are to be edited together, they have to have nearly identical volumes or one will hear the sound suddenly drop lower or suddenly jump louder. The edit will be obvious. The term “zero crossing” describes when the two sounds are nearly identical in volume so an edit can be done with good results. It is a term that is coming more into use now that audio editing is being done on computer. One can see, on the computer screen, when the two sounds match up in a way that makes the edit possible.


0dBFS: Zero decibels Below Full Scale. (See glossary entries DECIBEL, ZERO VU, FSD and DIGITAL LEVELS.)


ZERO VU (0 VU): VU stands for “Volume Unit,” which is an agreed upon unit of measurement of sound equal to one decibel. In any given audio studio, many meters are used which have markings on them to show the increases or decreases of decibels. In other words, they show how loud or soft (low) the volume is. The meters are called “VU Meters” - Volume Unit meters. It is important to understand that “zero” on an audio meter does not mean a total absence of sound. To the contrary, when an audio meter reads “zero” (“0”), one can actually hear sound. The zero mark is used to judge sounds as being louder or lower than zero. One can have a sound that is MINUS (lower) or PLUS (higher) such as “-3” or “+2,” all relative to the zero mark on the meter. Therefore, “zero” on the meter has to first equal some agreed upon volume of sound. Zero has to indicate a precise amount and that amount has to be established and the meter set for that agreed upon amount. Only then can one use the meter to accurately judge “how loud” and “how low” sounds are - all relative to the zero setting on the meter. The following example mentions a tape recorder, but zero VU and setting standard levels fully apply to both analogue and digital audio lines and equipment - including all audio tape machines and computerised workstations. First, a standard calibration recording test tape is used. It is put on a tape recorder and played. The sound it plays has a very precise tone recorded by an accredited professional laboratory. The tape’s tone is then looked at, by a technician, on a precision reference meter. The “test meter” is exactly calibrated to industry standards by a certified laboratory. When the tone is played on the studio tape recorder, the output volume of the tape recorder is adjusted so that the needle on the meter goes precisely to “+4 dBm” - a setting on the needle’s dial. “dBm” means “decibel milliwatts” - decibels referenced to 1 milliwatt (1 thousandth of a watt). The volume of an audio signal, as expressed and measured in electrical terms, is a tiny amount of power - just thousandths of a watt. Audio technicians and operators use the “dBm” unit to measure very small increments above or below an agreed upon amount of volume. In setting each of the studio’s meters so that “zero” is the same agreed upon amount of volume for every meter, the technician then adjusts the tape recorder’s output volume so that his test meter’s needle came to a reading of +4 dBm. Plus 4 is used because that is what the professional audio industry agrees upon and it is also what manufacturers of audio mixing equipment use as their reference. When the test meter’s needle came to rest on its +4 dBm mark by adjusting the output volume of the tape recorder playing the calibration tone, then every one of the studio’s own meters could then be set (adjusted) so that their needles came to their “zero” mark when fed the same tone. (“Zero” on the studio’s own meters, were adjusted to equal +4 on the Technician’s reference meter.). Therefore each meter is set the same, and to the agreed upon industry standard. Note: The test tone on the laboratory’s calibration tape was recorded very exactly by the laboratory. The tone’s volume was set by the lab using a unit of measurement called “nanowebers.” A nanoweber is the scientific unit of measurement for magnetic strength. (See NANOWEBER.) Of course, recording tape is magnetic tape and volume (loudness) of its recording is based upon how many “nanowebers” (units of magnetism) are used when the recording was made. 200 nanowebers is a commonly agreed upon amount for best tape-recorded tones, and this is used on our lines as well.


ZIP, ZIP DRIVE: A computer magnetic storage cassette popular with personal computer owners because they can hold a lot of data and transfer it quickly. A zip drive is often used to copy lots of information off the Internet or to carry lots of computer data to another location (so one does not have to bring one’s own computer).    


ZIPPER EFFECT: Said of a vertical image on a TV screen, which has jagged edges. See DOT CRAWL. It’s the same thing.     


ZIP TO THE REAR: Said when mixing in surround sound when panning a sound from the front loudspeakers to the rear loudspeakers and the sound “zips” (jumps) to the rear speaker(s) and will not seem to smoothly move to them. This can be due to odd frequency conflicts between the sound itself, and the loudspeaker. By adjusting the sound’s eq. a bit, it should transition smoothly when panned.


ZOOM (ZOOM BOX): A USA company that makes home musician level recording equipment as well as many guitar special effects for performers.




ZONE, ZONES: 1) Dvd’s have available “zones” for specific types of data storage. One zone is for pictures, one zone is for audio, one zone is for graphic menus, etc. it is really zones of digital information - how the computerisation process of dvd’s separates the various different types of information.

2) Some d.v.d. audio discs can be played on a d.v.d. audio player or a d.v.d. video player. When a d.v.d. is made for this, it will have an “audio zone” that has the higher quality music when played back on a d.v.d. audio player and a “video zone” which has the same music, but is playable on a d.v.d. video player. Some companies are making dvd’s with the higher quality audio zone on one side and the video zone sound on the other side, while others are putting both zones on different layers of the same side of the d.v.d.