T
3-dB down point See passband.
3D sound A term used to describe a three-dimensional sound field. A true 3D sound field positions sound anywhere in a semi-spherical shell surrounding the listener. Sound must come from anywhere directly behind to directly overhead to directly in front of the listener and all points left and right. It if does not, it is not 3D sound. The term is popularly misused by multimedia companies to describe systems, effects and techniques purported to create 3D sound from two sources and designed for two-loudspeaker playback; however, the result is not 3D sound. It is enhanced two-dimensional sound. Strictly speaking, a broadening, widening, enhancing, or spreading of the left/right sound stage is not 3D. No two-loudspeaker system is capable of locating sounds directly to the rear of the listener; nevertheless, some of these systems truly impress. The best enhancement schemes come very close to recreating a quarter-spherical sound shell, extending to nearly 180 degrees left-to-right, approaching 90 degrees overhead, with greatly improved depth of field. For further information see the Ultimate Spatial Audio Index.
10Base-T See Ethernet.
T-1 (trunk level 1) A digital transmission scheme utilizing two twisted-pair capable of handling a minimum of 24 voice channels. Used for connecting networks across remote distances. [Newton]
TA See thermoacoustics.
tablature Music. A system of notation using letters, symbols, or other visual cues instead of standard notation to indicate how a musical piece is to be played. For example, guitar or banjo tablature typically consists of a diagram of the strings with finger positions indicated by numerals corresponding to the appropriate frets. [AHD]
talent cueing See IFB.
talkback 1. A recording console feature where a microphone mounted on the console allows the engineer to speak with the musicians during sessions -- a very useful feature when the console is located in a soundproof control room, or out in the audience for sound reinforcement systems. 2. A proposed Rane product line aimed at the coffin market, since abandoned.
talk box A poor man's vocoder. Popularized by Peter Frampton and Joe Walsh in the '70s. See Heil Talk Box.
talkover A term and function found on DJ mixers allowing the DJ to speak over the program material by triggering a ducker. Compare with voiceover.
tangential mode Acoustics. Sound reflecting between four surfaces (i.e., two sets of parallel walls). Compare with axial mode and oblique mode.
taper See potentiometer.
tapir Any of several large, chiefly nocturnal, odd-toed ungulates (hoofed mammals) of the genus Tapirus of tropical America, the Malay Peninsula, and Sumatra, related to the horse and the rhinoceros, and having a heavy body, short legs, and a long, fleshy, flexible upper lip. [AHD] (Don't confuse with "taper" above.)
Tappan, Peter (1928-2007) American physicist and acoustical engineer whose work background included Bolt, Beranek and Newman, and Kirkegaard & Associates where he was a principal consultant and vice president. The author of "Shattering Goblets with Amplified Singing," he consulted with Memorex for their famous "Is it Live or is it Memorex" commercial.
taste test or tongue test An actual voltage testing method recommended by Terrell Croft in his book The American Electricians' Handbook, published by McGraw-Hill in 1913. Here's the passage found on page 48:
"The presence of low voltages can be determined by 'tasting.' The method is feasible only where the pressure is but a few volts and hence is used only in bell and signal work. Where the voltage is very low, the bared ends of the conductors constituting the two sides of the circuit are held a short distance apart on the tongue. If voltage is present a peculiar mildly burning sensation results which will never be forgotten after one has experienced it. The 'taste' is due to the electrolytic decomposition of the liquids on the tongue which produces a salt having a taste. With relatively high voltages, possible 4 or 5 volts, due to as many cells of battery, it is best to first test for the presence of voltage by holding one of the bared conductors in the hand and touching the other to the tongue. Where a terminal of the battery is grounded, often a taste can be detected by standing on moist ground and touching a conductor from the other terminal to the tongue. Care should be exercised to prevent the two conductor ends from touching each other at the tongue, for if they do a spark can result that may burn."
And from the same book comes these words of wisdom for testing for the presence of electricity by touching the two conductors:
"Electricians often test circuits for the presence of voltage by touching the conductors with the fingers. This method is safe where the voltage does not exceed 250 and is often very convenient for locating a blown-out fuse or for ascertaining whether or not a circuit is alive. Some men can endure the electric shock that results without discomfort whereas others cannot. Therefore, the method is not feasible in some cases."
[We don't know how Mr. Croft died, but perhaps we could hazard a guess. Thanks RH.]
Another interesting item is the case of a Swiss musician who "tastes" combinations of notes as distinct flavors, according to a report in the science journal Nature. The young woman is a synaesthete and when she hears tone intervals, the difference in pitch between two tones, she not only can see the musical notes as different colors but can taste the sounds. Read all about it here.
tau Mathematics. In professional mathematical literature the symbol for the Golden Ratio, or Golden Rectangle, but now phi is the more common symbol.
taut-band Electrical meter mechanism. Consisting of a permanent magnet and moving coil. Favored for its friction free suspension, allowing precision measurements.
Tchebysheff or Tschebyscheff See Chebyshev.
tchotchke See chachka.
TCP/IP (transmission control protocol/internet protocol) A set of protocols developed by the Department of Defense in the '70s to link dissimilar computers across many kinds of networks and LANs. Popular with Ethernet users.
TDIF (Teac digital interface format) Tascam's (Teac) 8-channel digital audio interface to their DA-88 digital multitrack recorder, using unbalanced signal transmission and a DB-25 type connector.
TDM (time division multiplexing) Data Transmission. A transmission interleaving technique where multiple sources, say, data, voice and video, are broken up into pieces and each piece is assigned a unique time slot with no overlap between pieces. This allows simultaneous transmission of multiple signals over a common path.
TDS (time-delay spectrometry) A sound measurement theory and technique developed in 1967 by Richard C. Heyser at the Jet Propulsion Laboratories of the California Institute of Technology. For a detailed introduction to the theory and practice of TDS see Time Delay Spectrometry: An Anthology of the Works of Richard C. Heyser on Measurement Analysis and Perception by John Prohs.
TEDS (Transducer Electronic Data Sheet) Microphones. An electronic microphone system (applies to any transducer so fitted but microphones are relevant to this listing). Developed and standardized as IEEE P1451.4, it is an embedded IC and software system that allows the user to read stored information about a particular microphone -- make, model, serial number, calibration date, sensitivity, capacitance, impedance, etc.
TEF (time-energy-frequency) The term adopted to describe the entire spectrum of TDS measurements, including energy-time curves. Popularized by Richard Heyser through his participation in Synergetic Audio Concepts seminars. Made practical in 1979 by the Techron division of Crown International -- Cal Tech's first TDS licensee, and introduced as the TEF System 10.
tele- Distance; distant: telescope. (Greek tele- meaning far off.) [AHD]
telecommunication Communicating over a distance by wire, fiber or wireless means.
teleconferencing An audio conference held by three or more persons over a distance. Normal usage refers to voice conferencing, also termed audioconferencing that includes all forms of audio. The term is sometimes extended to include video and document, or data, conferencing. Note that the term does not mean telephone conferencing, but rather distance conferencing, although telephone lines are often used. [Thanks to RG at Q Factor for pointing out this important distinction.] Contrast with videoconferencing.
telemedicine A specialized form of videoconferencing optimized for medical uses. Also referred to as medical conferencing, it allows distance learning in medical education and delivers health care (including assisted medical operations) to patients and providers at a distance.
Telharmonium Invented and patented (US patent #580,035) by Thaddeus Cahill, in the 1890s, an amazing monstrosity weighing 7 tons that was the first device to successfully send music through a telephone connected to something similar to a gramophone cone that could be heard by an audience. Arguably the beginning of background music and synthesizers.
temperament Music. The building up of musical scales.
tempo Music. The speed at which music is or ought to be played, often indicated on written compositions by a descriptive or metronomic direction to the performer. [AHD]
temporal Of, relating to, or limited by time. [AHD]
temporal masking A specific kind of masking where time separates arriving signals.
Masking of a later arriving signal due to an earlier one is called forward masking. The effects of a loud first sound can last long enough to mask a later arriving softer one (periods less than 500 ms and greater than 10 dB loudness differences).
The opposite effect where an earlier sound is masked by a later arriving one is called backward masking, i.e., the second arriving event covers up the first arriving signal. This is only possible because the ear requires time to form an echoic image before it is processed by the central nervous system. If a later sound is much louder it can take precedence over an earlier arriving one (within about 100 to 200 ms).
TERC (tuned electromagnetic resonance collar) Communications. A non-acoustic voice sensor device developed by the Spinlab (signal processing and information networking laboratory) at Worcester Polytechnic Institute in Massachusetts that can create speech from an unspoken voice.
tercet Music. See triplet.
terminal strips See connectors.
tesla Abbr. T The unit of magnetic flux density in the International System of Units, equal to the magnitude of the magnetic field vector necessary to produce a force of one newton on a charge of one coulomb moving perpendicular to the direction of the magnetic field vector with a velocity of one meter per second. It is equivalent to one weber per square meter. [After Nikola Tesla.] [AHD]
Tesla, Nikola (1856-1943) Serbian-born American electrical engineer and physicist who discovered the principles of alternating current (1881) and invented numerous devices and procedures that were seminal to the development of radio and the harnessing of electricity. [AHD]
tetrode A type of vacuum tube having two grids, where one is used to reduce feedback related instabilities and oscillations. A tetrode has four elements: plate, cathode, control grid and screen grid.
thaumaturgy The working of miracles or magic feats, like designing and building a 24-bit audio converter that actually measures 144 dB dynamic range.
THD (third-harmonic distortion) See third-harmonic distortion.
THD (total harmonic distortion) A measurement technique rarely used, but often confused with the THD+N technique described below. Many people mistakenly refer to a "THD" measurement when they really mean the "THD+N" technique. (For completeness and the abnormally curious: a true THD measurement consists of a computation from a series of individual harmonic amplitude measurements, rather than a single measurement. "THD" is the square root of the sum of the squares of the individual harmonic amplitudes. And the answer must specify the highest order harmonic included in the computations; for example, "THD through 8th harmonic." [from Metzler] See the RaneNote Audio Specifications.
THD+N (total harmonic distortion plus noise) The most common audio measurement. A single sine wave frequency of known harmonic purity is passed through the unit under test, and then patched back into the distortion measuring instrument. A measurement level is set; the instrument notches out the frequency used for the test, and passes the result through a set of band-limiting filters, adjusted for the bandwidth of interest (usually 20-20 kHz). What remains is noise (including any AC line [mains] hum or interference buzzes, etc.) and all harmonics generated by the unit. This composite signal is measured using a true rms detector voltmeter, and the results displayed. Often a resultant curve is created by stepping through each frequency from 20 Hz to 20 kHz, at some specified level (often +4 dBu), and bandwidth (usually 20 kHz; sometimes 80 kHz, which allows measurement of any 20 kHz early harmonics). [Note that the often-seen statement: "THD+N is x%," is meaningless. For a THD+N spec to be complete, it must state the frequency, level, and measurement bandwidth.] While THD+N is the most common audio test measurement, it is not the most useful indicator of a unit's performance. What it tells the user about hum, noise and interference is useful; however that information is better conveyed by the signal-to-noise (S/N) ratio specification. What it tells the user about harmonic distortion is not terribly relevant simply because it is harmonically related to the fundamental, thus the distortion products tend to get masked by the complex audio material. The various intermodulation (IM) distortion tests are better indicators of sonic purity. See the RaneNote Audio Specifications.
theremin (aka aetherphone) Considered the first electronic musical instrument, invented in 1919 by Russian born Lev Sergeivitch Termen, which he anglicized to Leon Theremin. The theremin is unique in that it is the only musical instrument played without being touched. Interestingly, when granted a US Patent in 1928, there were 32 prior patents referenced, going all the way back to Lee De Forest. A theremin works by causing two oscillators to "beat" together. The beat frequency equals the difference in frequency between the two signals. Beats are a physical phenomenon occurring in the air when sounds are mixed. A theremin uses one oscillator operating well above the upper limit of human hearing as a reference tone, and another oscillator whose frequency is varied by the proximity of a human hand, for instance, to a capacitive sensing element shaped like an antenna. A typical machine has two antennas and you play it by moving your hands nearer to and farther from the antennas. One antenna controls the volume of the sound, while the other controls the frequency, or pitch, of the sound. Used together you can creates sounds that can range from being very sci-fi-ish -- a sort of quivering sound -- as heard in early sci-fi movies like The Day the Earth Stood Still, to very complex jazz licks. The theremin even appears as Dr. Hannibal Lecter's favorite instrument in Thomas Harris' bestseller Hannibal (Delacorte, 1999). It was the theremin that got Bob Moog (inventor of the Moog Synthesizer and considered the father of modern electronic music) interested in electronic music. Moog Music now makes some of the world's best theremins.
See the Theremin web ring for additional info; and to view the fascinating, bizarre, and stranger-than-fiction true-life story of Leon Theremin, check out the film (available on video), Theremin: An Electronic Odyssey, by Steven M. Martin (1994), including several performances by Clara Rockmore, perhaps the best theremin player ever.
thermal noise See Johnson noise.
thermion Physics.An electrically charged particle, especially an electron, emitted by a conducting material at high temperatures. Basis for the thermionic valve, or vacuum tube.
thermionic trigger See Schmitt trigger.
thermionic valve See vacuum tube and Fleming.
thermoacoustics (TA) "The study of the conversion of acoustic energy -- compression waves in a gas (sound) -- into heat energy and vice versa. Acoustic energy can be harnessed in sealed systems and used to create powerful heat engines, heat pumps, and refrigerators. Thermoacoustic devices use these compression waves to replace mechanical pistons, crankshafts, and valves, reducing the number of moving parts in their design and making them simple, reliable machines. Thermoacoustic cryocoolers generally have two major sections to their design: an electroacoustic transducer (like a loudspeaker) and a coldhead." See Q Drive Resonant Power Systems.
thermophone A telephone involving heat effects, as changes in temperature (hence in length) due to pulsations of the line current in a fine wire connected with the receiver diaphragm. [Webster 1913 Suppl.] Invented by H. D. Arnold who received U.S. Patent 1,398,687 covering its design and theory.
Thevenin's Theorem In simple terms, states that a complex linear circuit (i.e., no exponents or roots in its defining equations) can be replaced by a single voltage source and a series resistor. See All About Circuits' Thevenin's Theorem for detailed explanation. [After Léon Charles Thévenin.]
Thévenin, Léon Charles (1857-1926) French telegraph engineer most famous for his Theorem.
third-harmonic distortion The standard test used on analog magnetic tape recorders to determine the maximum output level (MOL), which was defined to occur at the magnetization level at which a recorded 1 kHz sine wave reached "3% third-harmonic distortion." Of course, third-harmonic distortion is nothing more than a measurement of the amplitude of the third harmonic of the input frequency and is the most prominent distortion component in analog magnetic recording systems. The third-harmonic level was used as a convenient figure-of-merit because the 2nd harmonic is difficult to hear, since it tends to reinforce the pitch of the fundamental. The 3rd harmonic is easy to detect on pure tones (although less so on music), thus it makes a good benchmark for comparing sound "off tape" with the original. The distorted tone has an edge to it, containing a component one octave and a quint (interval of a fifth in music) above the fundamental. For this reason the third-harmonic is also called a musical twelfth. Here's the interesting twist. This test was commonly abbreviated and listed on the specification sheet as "THD." Which, of course, was mistaken to mean "total harmonic distortion" instead of "third harmonic distortion." This led to it being mistakenly shortened to just "distortion," so you still find old analog tape data sheets, and many text books defining MOL as the point at which there exists "3% distortion," instead of the correct reference to "3% third-harmonic distortion" -- quite different things.
third-octave Term referring to frequencies spaced every three octaves apart. For example, the third-octave above 1 kHz is 8 kHz. Commonly misused to mean one-third octave. While it can be argued that "third" can also mean one of three equal parts, and as such might be used to correctly describe one part of an octave split into three equal parts, it is potentially too confusing. The preferred term is one-third octave.
Thompson filters See Bessel crossover.
Thuras Albert L. American engineer most famous as the inventor of the bass reflex loudspeaker. Thuras filed patent No. 1,869,178, "Sound Translating Device," on Aug. 15, 1930, granted July 26, 1932, for the bass-reflex principle while working at Bell Labs.
THX® Ltd. (formerly a division of Lucasfilm Ltd.) term meaning several things: 1) THX Digital Cinema: audio playback design and certification program for commercial cinema theaters; 2) THX Cinema: audio playback specification for home cinema systems; 3) THX Home: approved audio/video playback equipment meeting their standards of quality and performance, as well as DVDs, laserdiscs and VHS tapes mastered by them to meet their quality and performance standards. New categories are THX Mobile and THX Games. The term comes from two sources: George Lucas's first film THX-1138 (commercial version), and a somewhat tongue-in-cheek reference to Tomlinson Holman's eXperiment, after their original technical director, patentee and creative force behind all the above (who now runs TMH Corporation).
THX Surround EX Surround-sound format that matrix-encodes a third surround channel into the existing left and right surround channels in a Dolby Digital signal. This channel drives a center rear loudspeaker. Compare with DTS-ES.
TIA (Telecommunications Industry Association) Created in 1988 by a merger of the US Telecommunications Suppliers Association (USTSA) and the EIA's Information and Telecommunications Technologies Group (EIA/ITG). This organization works with the EIA in developing technical standards and collecting market data for the telecommunication industry.
Tice Clock An overt act of fraud perpetrated on the audio ignorant who suffer from acute aural hallucinations and beg to be separated from their money. See Bob Pease's wonderful "What's All This Hoax Stuff, Anyhow?."
tiger A great cat whose skin is striped, not just his fur.
TIM (transient intermodulation distortion) See IM.
timbre (pronounced "tambur") 1. The quality of a sound that distinguishes it from other sounds of the same pitch and volume. [AHD] 2. Music. The distinctive tone of an instrument or a singing voice.
time 1.a. A nonspatial continuum in which events occur in apparently irreversible succession from the past through the present to the future. b. An interval separating two points on this continuum. c. A number, as of years, days, or minutes, representing such an interval. d. A similar number representing a specific point on this continuum, reckoned in hours and minutes. 2. Music. a. The characteristic beat of musical rhythm: three-quarter time. b. The speed at which a piece of music is played; the tempo. [AHD] (Time is nothing more than a relationship between moving objects. Stop all movement and you stop time. An important concept in understanding just what time is, lies in understanding that time is in the universe; the universe is not in time. Which explains why it is not a valid question to ask, "How old is the universe?" The universe does not have an age; it is not in relationship with another moving object; it is not in time.) ["Time is nature's way of keeping everything from happening at once." unknown source but often contributed to Woody Allen and to Albert Einstein.]
Time-Align® Loudspeakers. Trademark of Ed Long for his proprietary crossover techniques.
time code or timecode General. A sequence of discrete numeric codes occurring at regular intervals used to determine time. Various time code formats and methods exist. The following are the most popular pro audio applications:
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SMPTE/EBU. A standardized 80-frame word embedded as part of motion picture or sound recording (standardized for recording by SPARS). A specific identity or address is assigned to each moment of time in a recording, broken down into HOURS:MINUTES:SECONDS:FRAMES.
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MIDI. MIDI time code (MTC), is used to synchronize MIDI systems with the rest of the audio and video world.
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AES3 or AES/EBU. Within this standardized digital audio serial interface are provisions for time data.
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Additional recording time code methods are Linear or Longitudinal Time Code (LTC), Vertical Interval Time Code (VITC), Burnt-In or Burned In Time Code.
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Time codes for purposes other than video and audio production include Inter-range instrumentation group (IRIG), Global Positioning System (GPS), Network Time Protocol (NTP), and Radio Clocks.
time delay No such thing; a misnomer. You cannot delay time (see above). Misused to mean signal delay or just delay.
time-difference microphone technique See: AB.
timpani See tympani.
tin ear An insensitivity to music or to sounds of a given kind: a writer with a tin ear for dialog. [AHD]
tinnitus Hearing. A sound in one ear or both ears, such as buzzing, ringing, or whistling, occurring without an external stimulus and usually caused by a specific condition, such as an ear infection, the use of certain drugs, a blocked auditory tube or canal, or a head injury. [AHD]
tin-pan (tinny piano) From the cheap pianos associated with music publishers' offices that sounded like banging on tin pans. In the mid-1880s, gave birth to the name Tin Pan Alley, a district (West 28th St. in Manhattan) associated with musicians, composers, and publishers of popular music, or the publishers and composers of popular music considered as a group.
toeology Tap dancing. [Decharne]
token ring A LAN baseband network access mechanism and topology in which a supervisory "token" (a continuously repeating frame [group of data bits] transmitted onto the network by the controlling computer; it polls for network transmissions) is passed from station to station in sequential order. Stations wishing to gain access to the network must wait for the token to arrive before transmitting data. In a token ring topology, the next logical station receiving the token is also the nest physical station on the ring. This mechanism prevents collisions on this type of network. Normally connected as a star-wired ring where each station is wired back to a central point known as the multistation access unit (MAU). The MAU forms a ring of the devices and performs the back-up function of restoring the ring should one of the devices crash or lose its cable connection.
ton Air Conditioning. Audio equipment rooms require lots of air conditioning, which is specified in "tons of cooling," i.e., it is a unit that specifies the size of an air conditioner. But 'ton' refers to weight so how does it apply to air conditioning, inquiring minds want to know? Well, simple really. It was derived from the amount of heat required to melt 1 ton of ice in 24 hours, and was standardized as 12000 BTU/hr. They used to cool office buildings and high-rises by dumping tons of ice into the basement and blowing hot air over it, or using it to cool water and then using heat exchangers to move heat from the air into the water. Of course in those days the ice came from the river in the winter and was stored until the summer heat waves. [Thanks, GD.]
tone 1. Music. a. A sound of distinct pitch, quality, and duration; a note. b. The interval of a major second in the diatonic scale; a whole step. c. A recitational melody in a Gregorian chant. 2.a. The quality or character of sound. b. The characteristic quality or timbre of a particular instrument or voice. [AHD]
tone controls The term most often referring to a two-band shelving equalizer offering amplitude control only over the highest (treble, from music, meaning the highest part, voice, instrument, or range) frequencies, and the lowest (bass, from music, meaning the lowest musical part) frequencies. Sometimes a third band is provided for boost/cut control of the midband frequencies. See also Baxandall tone controls.
tonic Music. Of or based on the keynote. [AHD]
tootle To try the notes in an under tone, as a singing-bird, before beginning the whole song. [Kacirk] The act or sound of tooting softly and repeatedly, as on a flute. [AHD]
topology Electronics. The interconnection pattern of nodes on a network. The logical and/or physical arrangement of stations on a network (e.g., star topology; tree topology; ring topology; bus topology, etc.). The geometric pattern or configuration of intelligent devices and how they are linked together for communications. [IEEE] Mathematics. "The branch of geometry concerned only with those basic properties of geometric figures that remain unchanged when the figures are twisted and distorted, stretched and shrunk, subjected to any 'schmooshing' at all as long as they're not ripped or torn. Size and shape are not topological properties since clay balls, dice, and oranges, for example, can be contracted, expanded or transformed into one another without ripping." [Who's Counting?, John Allen Paulos]
toroid The name for any doughnut-shaped body. Mathematics: a surface generated by a closed curve rotating about, but not intersecting or containing, an axis in its own plane [AHD]. The shortened popular name for the doughnut-shaped (toroidal) transformers common to audio equipment; favored for their low hum fields.
TOSLINK (Toshiba link) A popular consumer equipment fiber optic interface based upon the S/PDIF protocol, using an implementation first developed by Toshiba.
total harmonic distortion See THD and THD+N.
T-pad See attenuator pad.
T-powering also known as A-B powering. Microphones. Named after the German word Tonaderspeisung, It is a special purpose powering system designed for T-power microphones, usually electret or condenser designs. Originally standardized as DIN 45 595.
TPDF (triangular probability density function) Also called triangular dither. The most popular form of dither signal, described in detail in the landmark paper by Stanley Lipshitz, Robert Wannamaker, and John Vanderkooy, "Quantization and Dither: A Theoretical Survey," published in the J. Audio Eng. Soc., Vol. 40, No. 5, 1992, pp. 355-375 (issue available from the AES, but only recommended for the mathematically needy). As the name implies, TPDF describes a probability density function shaped like a triangle, instead of the more often seen bell-shaped curve. For dither use, the extremes represent the maximum possible quantization error of ±1 LSB. Also very popular is a variant known as shaped triangular or high-passed TPDF, which is essentially high-pass filtered triangular dither that places most of the dither energy at higher frequencies making it less audible.
tracking power amplifiers A term used to describe audio power amplifier designs utilizing a variable power supply for the output, and a means of controlling the power supply based upon the input signal. This scheme improves efficiency. See Class H Amplifiers and compare with rail-switchers.
trademarks See USPTO.
Traf-O-Data See Microsoft.
train wreck DJ. Turntablist reference to two records falling out of sync. See DJ Terminology for more terms.
trainspotter DJ Music. Any person who identifies all the details about the music a DJ plays, particularly adept at esoteric and obscure details. Derived from the traditional definition of someone who could identify every train car of a particular railroad company.
transcendental number Mathematics. 1. Not capable of being determined by any combination of a finite number of equations with rational integral coefficients. 2. Not expressible as an integer or as the root or quotient of integers. Used of numbers, especially nonrepeating infinite decimals. [AHD]
transducer Electrical. A device, such as a microphone, or loudspeaker, that converts input energy of one form into output energy of another.
transfer function Electronic circuits. For a linear system, the ratio of the LaPlace Transform of the output to that of the input with no other input signals and initial conditions zero.
transform switch Turntablist mixers. This switch selects either phono or line as the channel source, but is commonly used for transforming, or quickly gating the source on and off.
transformer Electronics. A passive component that uses electromagnetic induction to increase or decrease alternating electric energy (voltage and current), usually consisting of two wirewound coils (windings) inductively coupled. A step-up transformer raises voltage and a step-down transformer lowers voltage. See Rod Elliott's articles for a thorough and clear exposition of transformer details (highly recommended).
transient discontinuous sound Acoustics. An intermittent sound decaying with time, especially as a simple exponential function of time. Characterized as a passing burst of sound marked by breaks or interruptions.
transient response The reaction of an electronic circuit, or electromechanical device, or acoustic space to a non-repetitive stimulus such as a step or impulse response. It is the result to a sudden change in the input that is nonperiodic. For example, percussive instruments produce primarily transient sounds. The transient stimulus and resulting response are characterized by the amplitude and the rise time (and fall time if it is an impulse), overshoot, and settling time. The standard reference is to note the maximum amplitude and the time required to reach within 10% of the steady-state value. For a real world example of the comparative transient responses for a full-range and a 3-way loudspeaker system, see Siegfried Linkwitz's Group delay and transient response; also see group delay.
transistor (transconductance + varistor) Electronics. 1. An active semiconductor device with three or more terminals. It is an analog device. 2. A semiconducting device for controlling the flow of current between two terminals, the emitter and the collector, by means of variations in the current flow between a third terminal, the base, and one of the other two. [IEEE] See: The History of the Transistor.
transonic Acoustics. Of or relating to aerodynamic flow or flight conditions at speeds near the speed of sound. [AHD]
transversal equalizer A multi-band variable equalizer using a tapped audio delay line as the frequency selective element, as opposed to bandpass filters built from inductors (real or synthetic) and capacitors. The term "transversal filter" does not mean "digital filter." It is the entire family of filter functions done by means of a tapped delay line. There exists a class of digital filters realized as transversal filters, using a shift register rather than an analog delay line, with the inputs being numbers rather than analog functions.
Trautonium Synthesizers. An early synthesizer from 1928. A monophonic instrument using a stretched wire over a resistor like a ribbon controller, with added pedals and keys. It made the vicious bird sounds in Alfred Hitchcock's "The Birds."
traveling wave Something vibrating creates a wave pattern that travels through a medium from one place to another.
treble clef Music. A symbol indicating that the second line from the bottom of a staff represents the pitch of G above middle C. Also called G clef. [AHD]
tree topology A LAN topology that recognizes only one route between two nodes on the network. The map resembles a tree or the letter T.
tremolo 1. A tremulous effect produced by rapid repetition of a single tone. A similar effect produced by rapid alternation of two tones. 2. A device on an organ for producing a tremulous effect. 3. A vibrato in singing, often excessive or poorly controlled. [AHD] [Think: amplitude modulation.]
triamp, triamplified, or triamplification Term used to refer to a 3-way active crossover where the audio signal is split into three paths, and using separate power amplifier channels for each driver.
triangle wave A periodic waveform characterized by a 50% duty cycle and a Fourier series consisting of odd-ordered, equal phase, sinusoidal harmonic components of its fundamental frequency with amplitudes (coefficients multiplying the magnitude of the fundamental sine wave) equal to 1/n², where n equals the harmonic number. Therefore the first few harmonic amplitudes are 1/9, 1/25, 1/49, 1/81, etc. For a very cool pictorial, see Fourier Series: Triangle Wave Tool. And if you are missing the math, see Cuthbert Nyack's Fourier Series of Triangle Wave.
triangular dither See TPDF.
triboelectric effect An electrical charge produced by friction between two objects. [AHD]
Trimpin Seattle-based composer and sound artist who constructs fascinating sculptures from new, used and discarded musical instruments that actually play themselves.
triple point of water A system is at the "triple point" when ice (solid), water (liquid), and vapor (gas) coexist in equilibrium. This point is the freezing point of water and is set by international agreement to equal 273.16 kelvin (0 degrees Celsius; 32 degrees Fahrenheit)
triplen harmonics 3-Phase AC Power.The name for the odd multiples of the third harmonic (3rd, 9th, 15th, 21st, etc.), i.e., every third odd harmonic. An order of harmonic that is a multiple of three. Common to 3-phase AC voltage generators.
triplet Music. A group of three notes having the time value of two notes of the same kind. Also called tercet. [AHD]
trombonga Music. Invented by seven-time Grammy winner Eddie Palmieri this trombone-fueled music style combines Afro-Caribbean beats with frantic jazz piano improvisation.
trottery Dancehall. [Decharne]
troxelator See feedback troxelator.
TRPA1 (transient receptor potential #A1) (pronounced "trip-ay-one") Hearing. Protein that translates sound waves into nerve impulses. Discovered in 2004 by a research team lead by neurobiologist David Corey of Harvard Medical School (the team consisted of researchers at U.Va., Northwestern University, Duke University, Harvard Medical School and the National Institutes of Health.). This is the long sought missing link in the ear's conversion of sound waves into electrical signals that the brain can recognize as distinct sounds. The protein is located in a tiny channel located at the tips of the inner ear's hair cells (also found in mice, fish and fruit flies). [Reported in the online edition of the journal Nature: "TRPA1 is a candidate for the mechanosensitive transduction channel of vertebrate hair cells." Corey DP, Garcia-Anoveros J, Holt JR, Kwan KY, Lin SY, Vollrath MA, Amalfitano A, Cheung EL, Derfler BH, Duggan A, Geleoc GS, Gray PA, Hoffman MP, Rehm HL, Tamasauskas D, Zhang DS.] Also see U. Va. Researchers Unravel a Central Mystery of Hearing.
true response graphic equalizer A graphic equalizer whose output characteristics perfectly match the position of the front-panel slide controls. Contrast with proportional-Q and constant-Q designs. See Perfect-QTM.
truncate To eliminate without round-off some low-order bits, often after performing an arithmetic computation.
Tschebyscheff See Chebyshev.
TTL (transistor transistor logic) The workhorse digital logic integrated circuit family introduced as a standard product line in 1964.
TTM (turntablist transcription methodology) A system of music notation developed by John Carluccio in 1997, for turntablism (see below). His system uses a modified musical staff with the vertical axis representing the direction of rotation of the record and the horizontal axis representing time.
tube See vacuum tube.
turntablism A form of music founded by turntablists (see below), that is already mainstream enough that the Berklee College of Music publishing arm, Berklee Press has issued books and vinyl records for this music form. For further historical info see Miles White's "The Phonograph Turntable and Performance Practice in Hip Hop Music".
turntablist A performing artist who uses two or more turntables as music sources from which he/she creates original results by quickly cutting and mixing the sounds of each, using specially designed performance mixers such as Rane's TTM 56.
turntablist transcription methodology See TTM.
TVS (transient voltage suppressor) Originally MOV (metal oxide varistor) (GE trademark). Semiconductor devices designed to provide protection against voltage and current transients.
tweeter High-frequency loudspeaker. See crossover; also ribbon tweeter.
twin-tone IMD See IM.
TwinVQ (transform-domain weighted interleave vector quantization) Name of a music compression technology developed at the NTT Human Interface Laboratories in Japan. A transform coding method like MP3, AAC or AC-3.
twisted-pair Standard two-conductor copper cable, with insulation extruded over each conductor and twisted together. Usually operated as a balanced line connection. May be shielded or not. See cables.
two-bit Costing or worth 25 cents: a two-bit cigar.
tympani or timpani Music Instruments. A set of kettledrums.
