Glossary

AB stereo—Also known as time delay stereo, time difference stereo. Two-channel stereo recording technique which benefits mainly from the differences in time delay between the microphones (channels). Omnidirectional microphones are used in most cases.

acetate base—The transparent cellulose acetate plastic film which forms the foundation, the base, or backing for the magnetic medium that is placed on the tape or film by the manufacturer.

acoustics—A science dealing with the production, effects, and transmission of sound waves; the transmission of sound waves through various mediums, including reflection, refraction, diffraction, absorption and interference.

The characteristics of auditoriums, theaters, studio stages as well as their design.

ADC (analog-to-digital converter)—An electronic device used at the input of digital audio equipment to convert analog electronic signals to digital values whose numbers represent the level and frequency information contained in the original analog signal.

AES—Audio Engineering Society (professional organization).

alignment—For film and tape recorders, referring to the correct adjustment of the record and playback head position with respect to the exact attitude of the film or tape path, and also adjusts the electronics for the ideal frequency response.

ambience—The distinctive acoustics of a given location being recorded; the environmental sounds that create a mood and a sense of “place.” The resulting audio sources (i.e., fluorescent ballast hums, distant traffic, air conditioning ducts, etc.) create a relative constant characteristic that reverberates off the walls, ceiling, pavement, and so on.

amplification—Increase in signal level, amplitude, or magnitude.

analog—Electrical signal that continuously varies in strength. Not digital. Magnetic and optical sound recording and playback systems are analog.

anechoic chamber—A testing room free from echo. Usually used to test microphones and other audio equipment that must be free from reverberation. Special acoustical surface and angular walls are vital to deaden the environment of the testing chamber.

articulation—A quantitative measurement of the intelligibility of human speech, where 100 percent is completely understandable. For the typical sound reinforcement or communications system no more than a 15 percent articulation loss is acceptable.

asperity noise—Otherwise called hiss; caused by minute imperfections in the surface of the recording tape. The cheaper the tape, the higher the degree of imperfections in the surface, the higher the danger of tape hiss.

attenuate—To reduce a signal's strength. Attenuator: A device that reduces or weakens the amplitude of a signal. Used on volume control, also called a fader.

audio analyzer—A test instrument used by motion picture theater sound engineers. The device contains terminations of various values capable of carrying up to 150 watts of audio power. Included is an AC voltmeter for measuring the frequency response of amplifiers, equalizers, filters, and the overall frequency response of the sound system.

audio frequency—Any frequency within the range of normal audio sounds, whose sound waves undulate roughly 20 Hz to 20,000 Hz (Hz = cycles per second).

audio fatigue—A hearing weariness brought on by a constant sustaining soundtrack that does not let up in intensity, both in volume as well as complex detailed make-up, which oversaturates the ears as well as the viewer's brain to assimilate such long durations. First signs are tingling and “fuzzy” sensation in the ears, followed by a shutting down of brain attention, thereby protecting itself from constant bombardment.

backup—This term is mostly commonly used to describe having a protection redundancy recorder to guard against accidental erasure or loss of material, as in a DAT backup recorder to the primary nonlinear Pro Tools recording session or 24-track or DA-88 recorder. Such protection can also be made after a recording or edit session, as in making a backup of the hard drive at the end of the day, or making a DVD-RAM backup from the Deva's internal hard drive to ship to editorial.

balanced—See cable, balanced.

balanced connectors—Microphone cable connections in which both conductors are electronically symmetrical with the case and cable shield (ground).

balance stripe—Also known as guide stripe or balance track. A narrow stripe of magnetic material identical to the primary magnetic stripe that the audio signal will be recorded on and reproduced from. This balance stripe is not used for sound recording, but is used to maintain a level contact with the sound head.

bandwidth—Refers to the space in the frequency response of a device through which audio signals can pass (between lower and upper frequency limits, those points where the signal level has rolled off 3 dB).

bias—A direct current (DC) or high-frequency alternating current (AC) signal fed to a magnetic recording head with the audio signal in order to minimize distortion. (AC Bias ordinarily provides higher fidelity.)

bit rate—The amount of the binary information code included in the audio file; the number of bits assigned to each sample (not the sampling rate) limits the dynamic range. If you are working in a 16-bit system, you have 65,636 possible volume levels to work with in each sample of the recording. If you try to drive the signal to 65,637, you will experience clipping and distortion because no more 1s and 0s are left to use. The volume-level saturation geometrically increases as you work at a higher bit rate. If you were working in a 20-bit system, you would have 1,048,576 choices, and working in 24-bit would give you 16,777,216 for each sample.

blooping ink—An opaque paint-like ink that an editor can apply over splices to protect the join in the optical track from making popping or snapping sounds when it runs over the optical reader head of the projector.

BNC connector—Coaxial connector for RF connections.

boom—(microphone boom) A telescopic arm to which a microphone (and hanger) is attached. The boom is held up over the head of the actors by the boom operator to place the microphone in an ideal out-of-camera position to record the action in the scene.

boom operator—Person who operates an overhead microphone unit, such as a microphone boom, to place the microphone in the most desirable position to capture the best quality recording.

bounce-to-disk—A process by which an editor can choose which channels of an edit session he or she wishes to combine in a mixdown, creating either a new monaural or stereo audio file. This process is done inside the computer using the editorial software and does not involve outputting any audio signal out of the computer to achieve a new mixed combine.

boundary microphone—Also known as pressure zone microphone (PZM). In a boundary microphone, the capsule is fitted flush in a surface which is large and flat compared to the wavelength. This produces the ideal semi-omnidirectional pick-up pattern.

cable, balanced—An audio cable with three wires; two wires carry the signal, high (1) and low (–), and the third is a shield which is connected to the chassis or system ground. The signal leads are both of equal potential difference from the ground; hence are balanced with respect to the ground, which is sometimes referred to as “floating.”

cable, unbalanced—An audio cable with two wires. There is no third shielding and it is not grounded to the chassis or ground. Therefore, the signal leads are unbalanced.

cable attenuation—Also known as cable loss. Attenuation that a signal experiences when it is transmitted via a cable. It is dependent above all on the length of the cable and the frequency of the transmitted signal. Measured in dB/m.

cable length—The cable length is usually measured between the anti-kink sleeves of the cable (cable length without connectors).

capacity—Short for ampere-hour capacity; that is, the charge that can be delivered by a rechargeable battery. This value can be used to calculate the operating time of a unit powered by the rechargeable battery.

capstan—Rotating shaft used with a pinch roller which pulls magnetic tape stock through a tape deck mechanism at an exact rate of speed. This is necessary because, unlike film, there are no perforations to engage with sprockets.

cardioid response—A heart-shaped microphone pick-up, directional in various degrees of configuration; sound waves coming to the microphone's rear and sides are rejected and those directly in front of it are received, giving it its directional qualities.

CCIR—Comité Consultatif International Pour la Radio. The French term that basically means International Radio Consulting Committee, an organization that influences Central and Eastern Europe. This affects equalization standard settings on equipment and will not play back correctly on NAB (Western hemisphere) equipment.

click track—In motion picture or television sound recordings, an electronic metronome is applied to the audio recording so that musicians can synchronize the musical tempo with the visual action or frame rate. The channel carrying the metronome signal is known as the click track.

clipping—Occurs when the capabilities of an amplifier are exceeded. The result is very audible distortion, also visible on an oscilloscope.

colorization—Distortion of frequency response by resonances at particular frequencies.

compander—The combination of a compressor and an expander used together to achieve noise reduction and/or increase the dynamic range capabilities of recorders or audio systems.

compressor—(compression) A process whereby the dynamic range of the audio signal is reduced. This is accomplished by making the louder part of the signal quieter and/or quieter parts louder, as desired.

condenser mic—A microphone in which sound strikes an electronically charged diaphragm, which acts like a variable capacitor as it moves near a fixed plate of opposite polarity. Ultra-low moving mass insures extended frequency response. Condenser mics require phantom power to operate.

connector—Type of pin device at the end of a cable to either send (male) or receive (female) audio signals, power, sync pulse, and so on (e.g., XLR, Tuchel, phono jack, Lemo, etc.).

cross-talk—Audible signal that spills over from one line to an adjacent line.

cue control—A device on the recording machine for finding a desired cue or audio selection while winding (or rewinding) at high speed.

DAT (digital audio tape)—Specifically, 4 mm high-density magnetic tape loaded in a small cassette unit. Maximum length of DAT tapes run 120 minutes (at 48 kHz sampling rate).

dB (decibel)—A measurement of relative intensity of power or voltage, based on a logarithmic scale.

decoder—A device that reads the encoded signal or pulse and turns it into some form of control or usable information signal (e.g., 2-track print master decoded in the theater into its six component signal streams).

degaussed—A device with a powerful electric coil magnet that can be turned on and off for bulk degaussing purposes. The film or tape roll must be moved in a rotating motion as it is moved into and out of the magnetic influence, thereby degaussing the magnetic stock properly and not causing spikes or uneven erased areas.

digital—A system whereby a continuously variable analog signal is sampled at regular intervals (usually 44,100 to 48,000 times a second). Each sample is assigned a numerical value, encoded into discrete binary bits (1s and 0s to represent quantities) that establish a mathematical model of the original sound. Advanced method of recording that involves a sequence of pulses or on-off signals rather than a continuous variable or analog signal.

directivity index—Index for the dependency of the pick-up pattern on the frequency. The lower this is, the better the quality of the microphone.

discrete—A single audio channel carrying a signal with no attachment or dependency on any other channel; not a matrixed multichannel signal.

distortion—Undesired qualities in the sound signal, usually introduced by electrically generated devices or changes in the relative levels of the different frequencies involved, overloading the saturation maximums allowable for clear audio recording.

distortion during playback—A modification of the original audio signal appearing in the output of audio equipment that had not been present in the input during the recording process. The most common way of expressing distortion is in percent of original signal as total harmonic distortion (THD).

distortion while recording—An audio signal from the microphone to the recorded medium (analog or DAT) is distorting due to either overloading the record level beyond the capacity of the tape to accept the signal or by using underqualified preamplification power or overamplification (e.g., double phantom powering a microphone).

diversity reception—Reception technique to reduce signal cancellation caused by reflection. The signal is received several times and the best signal is chosen for amplification.

drop frame—(1) Hole in the reception caused by the cancellation of the high frequency at the antenna. The receiver hisses and speech reception is disturbed. (2) Drop-frame timecode is so named because the counting sequence skips, or drops, two frames every minute except at the tens of minutes (see Chapter 6).

dropout—Loss of a portion of the signal caused by lack of oxide on the portion of the tape, or by dirt or grease covering the portion of the tape, or by an interruption of the signal from the microphone to the record head. It is a term also used when a nonlinear session is locked to timecode and is either recording or in playback mode and the timecode reader (i.e., slave driver) loses the steady flow of timecode data and suddenly stops because there is no timecode stream to lock onto and follow.

DSP functions (digital signal processing)—referring to special algorithmic software plugins for audio signal processing equipment and digital audio workstations for altering audio signals in myriad ways.

dual diaphragm—Special capsule design in condenser microphones. This allows the pick-up pattern to be adjusted from omnidirectional through cardioid to figure-of-eight by means of the diaphragm bias.

dummy head stereo—Head-based 2-channel recording technique using a (plastic) separator body in the shape of a head between the two microphones.

dynamics—Term used to describe the intentional design of an audio event (or mix) to build in strategic quiet passages to help the perception of louder passages being bigger than they otherwise may appear. To strategically design in high and low points into a soundtrack so that the audience will not suffer from audio fatigue, greatly increasing the listening value; making an audio roller coaster ride.

dynamics range—The way in which sound volume varies; the difference (in dB) between the loudest and quietest portions of the audio signal, or between the maximum signal level of the audio performance and the noise floor of the electronic equipment.

emulsion—Magnetic batch mixture coating that is adhered to the base stock of film or tape for eventual audio recording and playback purposes.

encode (encoder, encoded)—Device that brings in electronic signals and alters the character or superimposes other information onto it (e.g., multichannel matrix encoding or noise-reduction encoding, etc.).

exciter lamp—A lamp housing in the optical head of a projector or Moviola whose light passes through the optical soundtrack image of the film and impinges on a photoelectric cell, causing current fluctuations that accurately reproduce the analog audio signal for playback.

feedback—In a PA system consisting of a microphone, amplifier, and loudspeaker, feedback is the ringing or howling sound caused by amplified sound from the loudspeaker being picked up by the microphone and being recycled through the system and reamplified, played through the speaker and being picked up by the microphone again, and so on.

flutter—Rapid change in frequency of an audio or video signal due to variations in tape or disc speed. Wow is usually considered a lower frequency speed variation. See wow.

Foley—A process whereby a Foley artist performs custom sync-to-picture audio events by watching the projected image of action and simultaneously performs the desired sound event in sync. Originally developed by Jack Foley at Universal Studios and eventually named in his honor at Desilu Studios. Foley sound is usually associated with footsteps, prop movement unique to the film, and cloth movement.

frequency—Number of times a signal vibrates each second, expressed as cycles per second (cps) or as Hertz (Hz).

frequency response (audio and video systems)—The frequency range over which signals are reproduced within a specified amplitude range. Generally expressed in dB versus Hz; example: 100–5000 Hz±5 dB.

fullcoat—Audio film stock where the magnetic emulsion covers the entire surface of the film, from edge-to-edge over the perforations.

gain—Amount of signal amplification.

gain brain—A signal processing device that can be adjusted to be less or more sensitive to the dynamics of an incoming audio signal, and then lift and compress the volume of that signal according to the operator's need both in preset decibel expansion as well as duration of sensitivity.

generation loss—Every time an audio or video signal is copied, whether it is transferred from one medium to another or 1-to-1 duplicate copies are made, there is always a generation loss. Generation loss is more pronounced in analog form than in digital form. There is a myth that digital does not suffer from generation loss. This is simply not true. Every time you make a copy of a signal, there will be some degradation.

graphic equalizer—A multiband fixed area of frequency influences that can be boosted or attenuated as needed. Thirty-band graphic equalizers are the most popular for postproduction work, with plus or minus 6 dB shifts with 6 dB boosters to make them 12 dB shifts per channel.

harmonic distortion—Unwanted signal components within a spectrum as multiples of the fundamental frequency. If this frequency is 1 kHz, the distortion produces signal components at, for example, 2 or 3 or 4 kHz (these components are given as a percentage of the useful signal).

head room—The amount of safe recording range above the established 0 VU (and whatever you have designated as equivalent on the digital peak meter; e.g., –18 dB to –22 dB) reserved for more robust audio event moments where additional momentary increased volume is desired, but before you hit distortion or maximum.

head stack—A rigidly fixed array of erase, record, and playback heads (or record, pilot sync, and playback heads) that are aligned precisely together to appropriately write or read audio information. Head stacks are often modular and can be removed and changed out with other variations, such as the Magna-Tech multichannel combinations or the Stellavox interchangeable head-stack arrays.

hertz (Hz)—the unit of measurement for frequency; 1 Hz is equal to one cycle per second.

high pass filter—A high pass filter is a filter that allows only those frequencies above a so-called limit frequency (called the crossover point or cutoff) to pass. In electroacoustics, high pass filters are often called low cut filters, bass filters, bass cut filters, bass roll-off filters, or rumble filters. High pass filters on microphones are usually used to reduce the effects of handling noise, pops, rumble (e.g., stage rumble), and low-frequency vibrations or to reduce the proximity effect in close miking situations.

hirose connector—Also known as HRS connector. Commonly used plug connector between a pocket transmitter and a clip-on microphone. Unfortunately without a fixed standard.

image frequency—Undesired carrier frequency, produced by the conversion of the receiving frequency into the intermediate frequency. The result is a second reception frequency as a mirror image around the intermediate frequency.

image rejection—The ratio of actual receiving frequency to image frequency. Given in dB.

impedance—Resistance to the flow of an electrical current, expressed as high or low impedance. Hi-Z or Low-Z, measured in ohms (Ω). A lower value means you can run longer lengths of cable without loss of signal integrity. Impedance expresses the AC resistance of a microphone or a set of headphones. It is dependent on frequency and is given at 1 kHz as the so-called nominal impedance. In recent years, an industrial standard has developed, setting the impedance of headphones at 50 or 600 Ω. With microphones, the input impedance of the following microphone amplifier should have at least three times the value of the nominal impedance, in order to prevent it from unnecessarily attenuating the microphone signal.

inputs—The program that enters a unit or system; a connector or receptacle into which a signal is fed.

interlock—To sync up two or more recorders or playback machines, either by mechanical or electronic means so that they will run in exact sync with each other.

jack plug—A common audio connector in consumer electronics and the music industry. Available in various diameters; in the hi-fi segment, 1/8” and 1/4” are widely used. Poles range from one to four (examples: headphone jack or jack of an electric guitar).

jack socket—A common audio connector in consumer electronics and the music industry. Available in various diameters; in the hi-fi segment, 1/8” and 1/4” are widely used. Poles range from one to four (examples: headphone jack or jack of an electric guitar).

jam sync—A process of synchronizing a timecode generator with timecode being played on a tape, and then reentering that timecode on to the tape. Done to extend code or to replace bad code drop outs without disturbing the continuous count of timecode.

KEM—Flatbed picture editing machine. The film (both picture and sound) are mounted on cores and placed flat on aluminum plates that are synchronized together using sprocketed rollers that can interlock to run in sync or disengage to run each roll of film independently for ease of editing.

kilohertz (kHz)—One thousand times 1 hertz (Hz).

layback—To transfer from one medium to another medium, usually in multichannel form, usually involving timecode lock-up to maintain synchronization. This term is usually used when describing transferring a nonlinear edit session from the computer software from which the picture and/or sound edit session was created, to another medium for presentation purposes (e.g., 24-track analog tape, multichannel perforated 35 mm film, 2-, 8-, 16-, 24-, 32-, or 48-channel digital tape, or to any kind of video medium. See also output.

limiter—An automatic control to reduce volume when the audio signal rises above a level that would introduce significant distortion.

lobar (pick-up pattern)—A microphone with a lobar polar pattern has the highest possible directivity. A lobar pick-up pattern is achieved with a shotgun microphone.

M-S stereo—In the M-S stereo technique, one microphone with any pick-up pattern picks up the sound from the front (middle) while another microphone with a figure-of-eight pick-up pattern is positioned at right angles to it (side). The M-S stereo technique produces an optimum mono signal and can be used to infinitely change the included angle.

Magna-Tech—A rugged rack-mounted film recording and playback machine. Extremely accurate and practical. One to 6 channels capable, using mag stripe (for mono) and full-coat for multichannel. Uses 60 cycle stepping motors for sync accuracy and, pushbutton choice of American 24 fps or European 25 fps standards.

MIDI (Musical Instrument Digital Interface)—A communication system between musical synthesizers.

monaural (monophonic)—A single audio channel; not stereophonic.

monitor—To watch, to listen; to oversee and be vigilant about quality control of something, as in “she monitored the digitization process.”

monitors—(1) One or more television monitors to view visual images. A specialized highly calibrated television monitor for professional use to judge color values and quality control. (2) A pair (or set, as in 5.1 audio imaging field) of audio speakers of high-quality standard to accurately reproduce an audio signal for professional use.

moving-coil (dynamic) microphone—The moving-coil microphone is the most frequently used dynamic microphone. It makes use of magnetic induction to represent sound; a coil connected to the diaphragm moves in a magnetic field and induces a voltage that corresponds to the curve of the sound. The microphone needs no external operating voltage—it always works!

Moviola—An upright picture and sound editing machine used between the 1920s through the middle 1990s. Ultimately replaced by nonlinear digital workstations, except in rare cases.

NAB—National Association of Broadcasters.

noise cancellation—A microphone designed to cancel ambient noise so that it will not be recorded. The housing of the microphone allows noise to reach both sides of the diaphragm simultaneously, thereby canceling each other out.

noise gate—A signal processing device that can be adjusted to various calibrated sensitivities to compress or cut out noise peaks that are stronger than some specific desired maximums of the desired signal, thus limiting unwanted audio anomalies from the audio track.

nondrop—Unlike drop-frame timecode that skips, or drops, two frames every minute, nondrop timecode does not drop or skip anything.

ohm (Ω)—The unit of measure of electrical resistance or impedance.

OMF—Open Media Framework is a file format technology designed to allow media-handling applications to communicate in a platform-independent manner, to speak a common language. The goal of OMF is to allow any OMF-compatible application that handles audio, video, picture, or other media to communicate with any other OMF-compatible application. It is most often used to take a Final Cut Pro or Avid picture-edited session and to convert that session into a Pro Tools session. OMF translates simple single, continuous timecode. OMF translates any number of audio tracks. It translates clip names (region names) and can translate it sample-accurate (precision sync).

omnidirectional—Picking up signal equally from all directions.

optical head—See exciter lamp.

output—Signal delivered from any audio or video device; also a jack, connector, or circuit that feeds the signal to another device such as a speaker or headset.

overtones—Individual component frequencies in a sound which when added to the fundamental signal helps to define its spatial quality (e.g., cathedral expanse).

pad—Attenuator, usually with an attenuation of 10 to 20 dB. Used in both audio and RF technology.

pan pot—A multichannel volume controller. In this case the pan pot does not control how loud the signal will be, as it usually rides in line with the volume fader control, but controls the spatial placement of the sound, whether it will favor to left or to right speaker; if hooked up to the surround speakers, the pan pot can literally fly sounds around the room by the placement of the joy-stick during the performance of the audio cue. See phantom imaging.

parametric equalizer—Unlike the graphic equalizer whose bands are precisely fixed to control exact sectors, a mixing console parametric equalizer has three or more (usually four to five) ranges of influence: low frequency, lower midrange, upper midrange, high end. Each influence can be adjusted in attenuation or amplification by dB steps or by fractions of dB. Each influence can also be adjusted on how broad a frequency range in that influence the user may want to effect. The user may want it to be quite broad or the user may want to narrow the swath for fine surgical work. The usual attenuation/amplification can be as much as 624 dB.

peak meter—Unlike the VU meter, which shows an average of the modulation volume, a peak meter shows the maximum amplitude hits, moment to moment. Some meters will hold that level for a fraction of a second for easier reading, unless superseded by a louder level.

phantom imaging—Sound that is reproduced through two or more speakers that, through the use of multiple speakers and deriving audio material from these speakers in a varying percentage balance, is imaged in a part of the listening envelope where there is no speaker (i.e., right and left channels phantom a center channel by giving certain parts of the signal program identical elements that will cause perceived central derivation).

phantom power—A method of remotely powering the preamplifier or impedance converter that is built into many condenser microphones by sending voltage along the audio cable. Phantom power is usually from 6 to 48 volts DC and is run along the same conductors that carry the audio signal. The electrical power is separated from the audio by using capacitors and special transformers.

phase—Timing relationship between two signals.

phase matching—In playback, a swimming sensation when two identical audio signals are lined up almost identically. This swimming sensation tells the dialog editor that his replacement reprint of production audio is perfectly in sync with the work track.

phasing—In recording, two identical audio signals (from two separate microphone input sources) that cancel each other out. This is most often noticed in two microphones that are placed in a non-X-Y pattern. The two microphone diaphragm capsules are separated too much, and as a moving sound source, such as a car passing by, changes from the source striking diaphragm 1 first a millisecond before striking diaphragm 2 to favoring diaphragm 2 first before striking diaphragm 1; the signal is in a moment of transition and winks out.

pick-up pattern—Also known as polar pattern, directivity. Directions from which a microphone is sensitive to sound waves. Pick-up patterns vary with each mic element and mic design. The two most common patterns are omnidirectional and unidirectional. According to their acoustic design, microphones differ in their sensitivity toward sound from different directions. Pressure microphones have a sensitivity that is largely independent of direction (omnidirectional pick-up pattern). Pressure gradient microphones have the pick-up patterns wide cardioid, cardioid, super-cardioid, or figure-of-eight. Interference microphones can be used to achieve a further concentration of the pick-up pattern (lobar pick-up pattern). As a special case, dummy head microphones achieve the pick-up pattern of the human ear/head (dummy head stereo).

pink noise—Pink noise is an electronic signal that has equal energy levels at all frequencies across the range from 20 Hz to 20 kHz.

PNO (program number)—An abbreviated term used on DAT recording machines that can lay down a tape location reference, using 1 to 99 for the number of countable cues.

polarization voltage—Also known as bias. A condenser microphone needs a polarizing voltage in order to generate the signal voltage that follows the audio signal.

polar pattern—A graph of a transducer's directional characteristics measured in a 360° pattern, and usually at several different frequencies. Speaker polar patterns indicate relative output level, whereas microphone polar patterns indicate relative sensitivity.

pop—(1) One frame of 1 kHz tone placed at the 2 frame of an Academy leader at the top of the reel (6 seconds from the Picture Start frame). This 1/24 of a second “pop” or “beep” is used as head line-up for sync relative to a unit of sound or a mixed predub or final mixed track. One frame of pop is also placed 2 seconds (or 3 feet in 35 mm terms) from the last frame of picture (also known as LFOP). (2) A thump or explosive breathy impact produced when a puff of air from the actor strikes the microphone diaphragm. This most often occurs with the P, T, and B consonants of speech.

pop filter—(1) A foam or cloth shield placed over a microphone to avoid popping consonant sounds from suddenly impacting the microphone diaphragm. Stretched nylon hose over a metal ring (such as a bent wire clothes hanger) can make a very effective pop filter in a pinch. (2) An electronic filter than can attenuate low frequencies where the popping sound exists (a high-pass filter with its cutoff at approximately 70 Hz to 100 Hz).

postconform—To postconform means that you are going use the EDL (edit decision list) generated by the nonlinear editing software (picture editing) to use with transfer equipment that will automatically ask for certain production audio tapes (whether analog or digital) and then have the timecode-driven audio deck automatically spin down to and transfer only the sections of the tape required (along with a prescribed pre- and postroll handles). These transfers would be transferred into perfect sync into a nonlinear sound editing software session. This procedure is used if (1) the picture editor's audio material is not trustworthy to warrant using the OMF method, and/or (2) if the original production audio tapes used timecode as a sync reference, thereby having the timecode signal on the tapes to follow. Often this procedure is used with video transfer tapes that are made at the laboratory during the original telecine process; but what good is it to postconform from a medium that is already in question as it is not the original material and is already de facto suffering from generation loss?

preamplifier (preamp)—An amplifier that strengthens weak signals such as those from a microphone, magnetic playback head, photocell, or phonograph pick-up to a level sufficient to drive a power amplifier.

presence peak—An increase in microphone output in the “presence” frequency range of 2 kHz to 10 kHz. A presence peak increases clarity, articulation, or apparent closeness.

pressure gradient microphone—Also known as pressure gradient receiver, directional microphone. In the pressure gradient microphone, both faces of the diaphragm are exposed to the sound field. In an ideal pressure gradient microphone, the voltage given off by the microphone depends only on the difference in pressure between front and back. This results in a figure-of-eight pick-up pattern. By adding time-delay elements, one-sided pick-up patterns can be achieved; for example, wide cardioid, cardioid, and super-cardioid.

pressure microphone—Also known as pressure receiver, omnidirectional microphone. In a pressure microphone, only the front of the diaphragm is exposed to the sound field. The voltage given off by the microphone depends only on the sound pressure at the front and is therefore essentially nondirectional (see omnidirectional). Depending on the diameter of its diaphragm, the pressure microphone becomes, to a certain degree, unidirectional with increasing frequency.

print thru—Print thru is an analog issue. As the analog tape passes over the head stack the recorded audio signal is laid on, the tape continues around the tension roller and winds onto the take-up reel. If the recorded audio was very loud, the highly saturated recorded molecules on the tape, due to the very loud signals that registered in the upper maximums of the head room on the peak meter, are vibrating much more strongly than quieter passages. As the take-up reel revolves and winds yet other layers of tape over these highly agitated passages, the excited magnetic molecules will affect the layers on either side of itself, both prior and following, causing influences of phantom audio imaging known as print thru. This gives you a faint reproduction of that sound approximately 1 second between each phantom prior to and following the actual recording.

proximity effect—Every directional microphone (pressure gradient microphone) has the property of providing a pronounced boost in low-frequency output when placed close to the sound source (less than 20 cm). This has physical reasons and is partly decisive for the sound of a vocal microphone.

quadraphonic—Four cardioid microphone capsules aligned at precise 90° angles to each other so that when reproduced in a listening environment with four audio speakers in proper spatial positioning, the signal will produce a realistic 360° envelope that will replicate the original environmental reality.

response—The sensitivity, frequency, and polar characteristics of a microphone.

reverberation—The sum of many reflections of a sound in an enclosed recording environment.

Rivas tape splicer—A precision film tape splicer (either 16 mm or 35 mm) that uses preperforated splicing tape for exact alignment. Clear tape is used for picture and white base perforated tape is used for the sound. “Rivas” is the name of a particular manufacturer.

sample rate—The number of measured moments in a second that digital data numbers represent the level and frequency information that models the audio signal. The two basic industry standards for sample rates are 44.1 kHz and 48 kHz (44,100 and 48,000 times per second). Played in real time these moments render a recreation of the sound. Look for the sample rate standards to rise to 96 kHz and possibly as high as 192 kHz within a decade.

session—(1) A contiguous length of time that a group assembles together to perform and/or record or for a picture editor or sound editor and the director (and any other participants) to work in a scheduled length of time. (2) In nonlinear terms, a software icon that contains all of the edit decision data that the picture or sound editor has worked with to create either a picture or sound reel of action. This icon session knows, through the editor's input access, where in the computer hard drives all of the digitized media material resides.

shotgun mic—Slang term for a highly directional tube-like cardioid microphone. This interference microphone uses a lobar pick-up pattern. Especially useful for reducing ambient noise in ENG applications.

sibilance—In speech, the overemphasis of “s” and “ch” sounds in speech, which causes undesirable sharp and shrilly spikes.

signal cancellation—One audio signal is combined with another audio signal that has varying degrees of identical information in it (being recorded at the exact same time) and will cancel out its counterpart in the first signal; like taking an image of something as a positive image and aligning it with its identical image in negative form—the two cancel each other out and become nothing. The audio signal material from the first source that does not have a counterpart in the second signal will be all that remains.

signal-to-noise ratio—The ratio of audio information of a signal that has unwanted hiss, rumble, hum, and other background noises in balance to the desired signal; measured in dB. The ratio of the largest possible output voltage to the smallest possible output voltage of an electroacoustic transmission device. The signal-to-noise ratio is the difference between the reference sound level of 94 dB (equivalent to 1 Pa) and the equivalent noise level. Studio condenser microphones generally have a signal-to-noise ratio of 74 to 64 dB (CCIR) or 84 to 74 dB (A).

sine wave (sinusoidal)—A signal wave signature that has a magnitude that varies as the sine of an independent variable. (See Chapter 6, Figure 6.9.)

slate—Slang term, “sticks.” Rectangular surface (either black background or white) on which the slate assistant can write data information on, for the camera to see just prior to snapping sync. Information such as production title, company, date, camera roll, sound roll, director's name, cameraman's name, as well as the scene number, angle designation and take number can clearly be seen. At the top of the slate is a hinged bar (usually painted with alternating black and white angled stripes) for ease in designating the exact frame of sync when the slate assistant is told to “mark it” and claps the hinged bar down onto the slate—causing an audible snap for the microphone to hear.

smart slate—The smart slate works identically as the conventional slate, in that data information is handwritten onto the white slate surface, the difference being that the smart slate has a wireless receiver that reads the running timecode transmitted from the audio recorder and displays it in large red LED numbers. These numbers run until the slate assistant claps the hinged bar down onto the slate, causing the two electrical contacts on the inside surfaces to touch and freeze the timecode so that the picture assistant can sync dailies back at picture editorial.

SMPTE—Society of Motion Picture and Television Engineers.

square wave—A signal wave signature that is periodic and equal to one constant on one half of the period and a different constant (which may be zero) on the other half. (See Chapter 6, Figure 6.9.)

SRT—Standard reference tape.

stereo—The audio signal is recorded using two discrete channels in parallel and when played back will yield a spatial presence with a balance left and right signal. Movement of audio-generating sources within the program will appear to move from left-to-right or right-to-left as the two microphones were set up to record them. See also quadraphonic.

supervising sound editor—The individual who is responsible for and heads the postproduction sound editorial team and various audio facility services to bring together a polished production dialog track, sound design, custom performed and edited Foley, and stereo backgrounds. He or she also oversees the mixing of the final rerecording process with the cut music sessions. The supervising sound editor is solely responsible to the director and producer and often is the contractor of the postsound edit process.

sync (synch)—The exact alignment of the audio event to the corresponding frame of visual action.

sync block—See synchronizer.

sync generator—A pulse generator producing the sync signals necessary to integrate the functioning of various pieces of sound, camera, or video equipment in relationship to each other.

synchronizer—Also known as a sync-block. When working with picture and sound 16 mm and 35 mm film, the most accurate synchronization device is the synchronizer, which is comprised of up to six side-by-side sprocketed wheels (known as gangs) coupled to each other with a solid metal rod. When one wheel turns, the others turn exactly the same because they are physically coupled together. Each full rotation equals one foot of film. These wheels have sprocket teeth on the perimeter edge, precisely engaging into the perfortion holes of the film stock, forcing the film to remain in rigid synchronization due to locking arms that are lowered and clicked into place. Each locking arm has two rollers with grooved glides that allow the sprocket wheel teeth to pass through; yet the roller holds the film in place against the wheel, so the film does not slip and slide out of sync with the picture or other mag-stripe strand of film.

Magnetic heads can be lowered down onto the magnetic film strands so that the sound can be heard. The heads feed the signal into a table-top amplifier.

The synchronizer does two things: (1) it keeps the picture and parallel tracks of sound to be kept in sync to one another; (2) it keeps track of the position of the film by the use of a precision foot-and-frame counter. This counter can be zeroed-out by the editor when he or she has locked the strands of film into the synchronizer in the desired line up positions (usually using a start mark or frame designation marking).

Even in today's nonlinear digital domain editing environment, going back to film—whether by negative cutting or use in the post-sound mixing process—the film synchronizer is the ultimate and most accurate way to guarantee sync in the film industry. (See Chapter 13, Figure 13.9.)

THD (total harmonic distortion)—A measure of nonlinear harmonic distortion given in percent. Nonlinear harmonic distortions are signals that were not present in the original before the signal was converted by the headphones. These unwanted signals are caused by the diaphragm, whose movements do not precisely move in time with the electric signals that cause it to move. Unfortunately, this is a feature of all electroacoustic transducers. Although it cannot be completely eliminated, suitable steps can be taken to minimize it. However, the user is not interested in why this distortion takes place but in how great the level of distortion must be for it to become perceptible. According to the findings of several research projects, a total harmonic distortion of 1 percent in the frequency range of 100 to 2000 Hz is imperceptible. Below 100 Hz, the perceptibility threshold lies at 10 percent.

timecode—“Electronic perforations.” A numbering system developed by SMPTE that assigns a number to each frame: the frame address, denoted by hours, minutes, seconds, and frames. There is a visual timecode for visual reference as well as an audio timecode (sounds like a constipated electronic cricket on steroids) which matches its visual reference.

transducer—A device that converts one form of energy to another form. A microphone transducer converts acoustical sound energy into electrical signal energy.

transfer bay—An array of equipment (usually in a dedicated room) that can transfer audio or video medium from one source to another source. Such transfer bays have calibration tools and meters so that accurate and precise 1-to-1s can be made to the closest tolerances.

VITC (pronounced vit-see; vertical interval time code)—This timecode reference is recorded in the video frame line vertical interval. Computers can read this timecode very accurately.

VU meter (volume unit meter)—Used in most American equipment for measuring audio signal levels. It averages the sound, showing a percentage modulation and is not linear in dB, unlike the peak meter.

watt—A unit of measure for electrical or acoustical power.

wavelength—Provided that the wave is perfectly regular (such as a sine wave) this is the distance between successive peaks.

wow—A cyclic fluctuation in pitch due to mechanical malfunction (usually tension rollers) or in constant speed of the transport capstan, as in wow-and-flutter.

XLR—Professional connector (having three or more conductor pins) with an outer shell that shields the connection and makes a solid male/female lock. Most commonly used for balanced audio signals for microphone and line feeds. The XLR-type connector is sometimes called a “cannon” connector, so-named for the original manufacturer.

X-Y pattern—A pair of cardioid microphones or mic elements aimed at crossed directions, with the two microphone diaphragms as close together as possible, putting the two signals in phase.