rack rail – strips of metal with screw holes on each side of the rack used to mount rackable electronic hardware and accessories. Also called a rack strip. See also U.
rack screws – screws used to attach equipment to an equipment rack. Three different screw sizes are used: 10-32, 12-24, and M6 (6 mm metric). Although 10-32 was the original screw size, 12-24 appears to be more commonly used today.
rack space – the standardized size of the front panel of equipment that fits in a rack, which is 1.75 inches by 19 inches. See also U.
radar – a device that can determine the presence, direction, distance, and speed of aircraft, ships, vehicles, and other objects, by transmitting pulses of EHFradio waves that are reflected off the object back to the device.
Radial Engineering Ltd. – a manufacturer of professional audio products based in Vancouver, British Columbia, that offers a wide range of products that are sold under brand names such as Radial, Tonebone, Primacoustic, Reamp, and Zebracase. In 2018, Radial was acquired by Mike Belitz, former president and CEO of Ultimate Support, in a venture with Regimen Partners, a private equity firm from Vancouver, BC.
radian – a unit used to measure angles, equal to an angle at the center of a circle with an arc equal to the length of its radius. The magnitude in radians of one complete revolution (a circle or 360°) is the length of the circumference divided by the radius, or 2πr/r = 2π. Since 2π radians equals 360°, one radian is equal to 180/π degrees, or about 57.296°. Abbreviated as rad.
radiation pattern – the angle and coverage of sound projected from a loudspeaker as indicated on a polar graph. A speaker with a wide directivity (also called wide or broad dispersion) maintains a consistent sound pressure level (SPL) for both the on-axis and off-axis sound. A speaker with a narrow directivity speaker (also called narrow dispersion) has on- and off-axis levels that are substantially different. Radiation patterns are frequency-dependent. When the wavelength is large relative to the size of the driver, the radiation pattern tends to be omnidirectional. As the wavelength becomes smaller relative to the driver size, the radiation beam begins to narrow. Therefore, as the frequency increases, the sound becomes more directional. Also called dispersion pattern, directivity, or directionality. See also dispersion angle.
radio edit – a special mix that is used to make song more suitable for radioairplay. It may be adjusted for things, such as length, profanity, subject matter, or format. Often radio edits are used for the commercial single version of the song, but not always. Also called a radio mix.
Radio Data System (RDS) – a system for embedding small amounts of digital information in conventional FM radiobroadcasts. The standard, originally started as a project of the EBU, has become an international standard of the IEC. The US version is officially designated at the Radio Broadcast Data System (RBDS) and is slightly different from the European version. RDS is capable of displaying station ID, traffic information, program information (PI), and genre. It also has the ability to lock onto best possible frequency for a stations with alternate frequencies (AF).
radio receiver – (1) An electronic device that receives incoming modulatedradio waves and converts them into sound or data. (2) A radio set. Sometimes called a wireless (an old British term). Called a radio for short.
radio signal – a radio wave used to transmit and receive messages.
radio station – an installation or organization used for the production and transmission of AM or FMradiobroadcasts.
radio wave – an electromagnetic wave within the range of the radio frequency spectrum. Such a wave can be man-made, such as a transmissions from radio stations, or natural, such as emissions from lightning and sunspots.
RAID (Redundant Array of Independent Disks) – a technology for storing data on multiple hard disks to protect data in the case of a drive failure, although not all versions provide redundancy. Data is distributed across several drives in one of several schemes, referred to as RAID levels. The different levels are designated RAID 0, RAID 1, RAID 2, etc. Each RAID level provides a different balance among the goals of reliability, availability, performance, and capacity. Originally named redundant array of inexpensive disks. See also NAS.
rainstick – a percussion instrument originally from Chile made from a branch of a dried cactus that is hollowed out, filled with small pebbles, and capped at both ends. It makes the sound similar to falling rain when tilted slightly. The Chilean name is palo de lluvia. Also spelled rain stick.
.ram – file extension for a file linking to a RealAudio file.
RAM – Random Access Memory. Michrochips used as computer memory to store data, including the instructions of a computer program. It is considered random access because the data does not need to be stored in any particular order.
random noise – (1) A random fluctuation in an electrical signal characteristic of all electronic circuits. There are a variety of sources and types of random noise, such as thermal noise and flicker noise. (2) A noise in which each frequency within an octave has an equal probability of occurring. See noise colors.
random note generator – a device in a synthesizer that creates unpredictable tones at a regular rate.
rare earth magnet – a strong permanent magnet made from alloys of rare earth elements (those with atomic number from 57 to 71). Rare earth elements are not all that rare, being commonly found in the earth's crust. They have high electrical conductivity and produce significantly stronger magnetic fields than other types of magnets, such as ferrite or alnico magnets. Because rare earth magnets are extremely brittle and susceptable to corrosion, they are usually plated or coated. The most common rare earth magnets are neodymium and samarium-cobalt.
rarefaction – the portion of a sound wave in which air molecules are spread farther apart forming an area of lower pressure. The opposite of compression.
raspy – (1) A descriptive term for a harsh sound. (2) A descriptive term for vocals with excessive sibilance or with a piercing sound due to peaks in the 6 to 7 kHz range.
rasgueado – a guitarstrumming technique commonly associated with flamenco guitar or classical guitar. It uses the fingers of the strumming hand in a rhythmically precise and often rapid strumming pattern, strumming the strings upwards with the fingernails or downwards with the fingertips. Also called rageo, rajeo, rasgueo, rasgeo, or rasqueado.
raster – (1) The scan pattern on a television set in which the electron beam of a cathode ray tube (CRT) scans lines from side to side and from top to bottom. (2) A pattern of closely spaced rows of dots that form an image (as on the cathode-ray tube of a television or computer display). (3) The electronic circuit that creates the scanning spot that traces the lines on the TV screen.
rate – the length of time during which the depth circuit of a delay program completes one full increase or decrease cycle for the nominal delay time, resulting in a vibrato sound.
rate control – a parameter on a synthesizer that controls the rate or timing of certain actions, such as the attack, decay and release portions of an ADSR envelope.
rated bandwidth – the frequency range (usually 20 Hz to 20 kHz) over which the performance of an audio device is evaluated with respect to rated specifications, such as power output, distortion, etc.
rated load impedance – the input impedance of a device when a load is present (another device or equipment is connected).
rated output – (1) The maximum output that can safely be handled by a component, circuit, device, or system. (2) The maximum output of a component, circuit, device, or system as established by the manufacturer.
raw – an audio file format used for storing audio in a raw form, that is, without a header or metadata. Data is usually written using PCM, but other codecs are sometimes used. It is mainly used for technical testing, but can be used with some audio players, but because there is no header, the user must input information, such as the type of encoding, the sample rate, the bitrate and othe data. Raw files use the extension .raw, .pcm, or none at all. Also called RAW Audio.
RCA – Radio Corporation of America. A US electronics company in existence from 1919 to 1986 and later known as the RCA Corporation. GE took over RCA in 1986 and sold off various assets. It sold its interest in RCA Records to Bertelsmann, which became BMG Music (Bertlesmann Music Group). GE sold the GE and RCA brand rights for televisions and othe consumer electronics to Thomson Electronics of France.
RCA 44 – a bidirectionalribbon microphone developed by Dr. Harry F. Olson of RCA and introduced in 1931. The 44-A was RCA's first permanent magnet ribbon microphone. With the smooth sound of the ribbon and its attractive styling, it was well received by broadcasters well into the 1940s. Updates in design and improved magnet materials
resulted in the 44-B and 44-BX. It became a classic and remained in production until the mid 1950s.
RCA 77 – a unidirectionalribbon microphone developed by Dr. Harry F. Olson of RCA and introduced in the early 1930s as the RCA 77-A. It used double ribbons that combined a pressure unit with a velocity unit to achieve the unidirectional pattern. Improvements in magnet material resulted in a significant reduction in size with the 77-B. The 77-C and 77-D introduced multiple patterns. The 77-D and 77-DX were single-ribbon models produced after World War II, and remained in production until 1973 when RCA ceased production of all microphones.
RCA Records – a recording label in the US. In 1929, Radio Corporation of America (RCA) purchased the Victor Talking Machine Company, then the world's largest manufacturer of phonograph records and phonographs (including the Victrola) and formed RCA Victor. It later became RCA Records. Today it is part of Sony Music Entertaiment.
RealAudio – a proprietary audio file format designed by RealNetworks for streaming audio over the internet. It uses a variety of codecs, ranging from low-bitrate formats for use with dialup modems to high-fidelity formats suitable for music. Although it was once widely used by many internet radio stations for streaming music, RealAudio has lost out to other formats that have become more popular. It uses the .ra file extension. A file using the .ram extension is a text file with a link to an internet address where a RealAudio file can be found. It does not contain any audio data.
Real Sound Lab SIA – a company headquartered in Tokyo, Japan, that makes audio software and hardware.
real-time dubbing – duplicating a recording tape at its normal playing speed, which results in higher quality than a high-speed dubbing.
real-time input – MIDI data that is input as it is being played, such as during a performance or a studio recording session, as opposed to a step input.
re-amp – the process of running a recorded signal (such as a DI guitar) back through an amplifier and speaker to obtain the sound or effect of the amp/speaker system. Although done originally with guitars, the process has expanded to many types of instruments. Short for re-amplify. Although sometimes spelled without the hyphen, care must be exercised as Reamp® is a trademark of the Reamp Company.
Reamp Company – a company located in Oakland, CA, founded by John Cuniberti in 1994 that designed and built Reamp®, a device that provided the ability to feed a previously recorded guitar track back into an amplifier to be re-recorded. Reamp was purchased by Radial Engineering in 2012.
rear surround speakers – one or two loudspeakers placed behind the listening position in 6.1-channel or higher surround theater systems. Also called rear speakers or back surround speakers.
REAPER – Rapid Environment for Audio Production, Engineering, and Recording. A digital audio workstation developed by by Cockos.
Reason – a computer program for creating and editing music developed by the Swedish company Propellerhead Software, that emulates a rack of hardware synthesizers, samplers, signal processors, sequencers, mixers, and other devices that can be freely and abitrarily interconnected.
reassign – to re-route or designate an alternate output bus for a given bus or output in a console or DAW.
recap – to replace the capacitors in audio equipment either because they are beginning to fail or to improve audio quality.
REC – (1) One of several abbreviations for receive. (2) Abbreviation for record.
recce – to visit a location ahead of time to determine the suitability for recording, filmmaking, and/or videoing, to avoid any potential sound or lighting issues. The term is used in media, radio, and TV production primarily in the UK, Australia, New Zealand, and South Africa, and is a term borrowed from the miltiary, derived from reconnaissance or reconnoiter. In the US the term site survey is more commonly used.
receive – (1) To pick up or detect radio signals and convert them into other forms, such as audio or video. Abbreviated as REC, RCV, or RX. (2) To acquire sound, such as a microphone acquring a sound wave.
receiver – (1) A device that picks up incoming radio signals and converts them into other forms, such as audio or video. Sometimes called a radio receiver. Abbreviated as RCV or RCVR. (2) Short for AV receiver.
While the precise years varies slightly by source, they are fairly close to those shown above. Some historians call the magnetic tape era the high-fidleity era, and some break it down further into the monaural era and the stereo era. For more details, see The History of Audio Recording.
record enable – to place a track or channel on a recording device into the state of being ready to record. When the device is in record mode and the start (play) button is pressed, only record-enabled tracks will record audio (usually while monitoring the input audio), while non-enabled tracks normally play previously recorded audio (if any). Also called track armed.
Recorderman technique – a drum miking technique somewhat similar to the Glyn Johns technique, but using two microphones instead of four. It consists of one cardioid microphone suspended about 32 inches above the center of the snare drum, pointing straight down. A second cardioid mic is positioned near the drummer's right shoulder, pointing directly at the snare drum also about 32 inches away. The kick drum should be equidistant from both microphones. The two tracks are panned left and right about 70% to 80%. The technique comes from a person using the user name Recorderman on one of the recording forums who is credited with popularizing the technique.
Recording Academy, The – an organization of professionals in the recording business such as musicians, producers, recording engineers, and others. The Recording Academy is probably best known for the annual Grammy Awards. It was formerly known as the National Academy of Recording Arts & Science (NARAS).
recording contract – a legal agreement between a record label and a recording artist or group. The details of recording contracts vary with the artist, but typically the artist agrees to record a song or series of songs for the label, which the label sells and promotes, in return for a payment or a share in the royalties. Artists usually are restricted to record for that label exclusively. Also called a record deal.
recording engineer – a specialist skilled in the use and techniques of recording, mixing, reproducing, and amplifying sounds, whether live or in the studio. Also called an audio engineer, audio technician, audio technologist, sound engineer, sound operator, or sound technician. Although these terms are often used interchangeably, they can mean different things depending on the context. Compare with audio engineer, studio engineer, or sound engineer.
recording solo – a switch that turns on the audio from one channel while muting all remaining channels.
recording studio – a facility for making audiorecordings. A recording studio usually consists of at least two rooms: (1) the studio or live room, where music, dialog, and other sounds are created, and (2) the control room, where the audio from the studio is recorded and processed. A well-designed studio will have good acoustics and a high degree of sound isolation between rooms and the outside world.
recordist – (1) A person who makes a sound recording. Also called a recording engineer. Sometimes called a recorder, but that term more often refers to a recording machine. (2) The person who controls a tape machine. Also called a tape operator. (3) The person on a film set in charge of sound recording. Also called sound recordist.
record label – (1) A round paper disc (label) in the center of a phonograph record that provides the title, artist, manufacturer, and other information about the record. (2) A distinctive brand used by a record company to market its catalog of music. (3) The record company itself. A record label coordinates the production, manufacture, distribution, marketing, and promotion of sound recordings, seeks out and develops new talent (A&R), and manages contracts with recording artists. Sometimes a label also operates a publishing company that manages and enforces the copyright of music. The term record label comes from the label in definition #1 above. Also called a record company.
record mode – the configuartion of a recording device when it is set to recordaudio once the start (play) button is pressed. Only record-enabled tracks will record audio, while non-enabled tracks normally play previously recorded audio (if any). The recorded tracks can be listened to later using the playback mode.
recursive equation – an equation in which the result of one calculation is used to make future calculations. They are often used to make filter and equalization calculations in digital implementations, because they speed up the computations. A filter that uses a recursive equation is known as a recursive filter. Also called a recursive formula.
red noise – a random noise in which the energy content decreases at 6 dB per octave, thereby having most of its energy in the low frequencies. Also called brown noise or Brownian noise after Robert Brown. See noise colors.
red-light syndrome – a slang term for the condition in which a performer becomes nervous or gets stage fright when the recording button is pushed and the “red light” comes on.
reed – a thin strip of material used on some musical instruments that vibrates when air passes over it to produce a sound. The reeds of most woodwind instruments are made from the giant cane plant while tuned reeds used in harmonicas and accordions are made of metal or synthetic materials.
reedy – a descriptive term for a sound that is high-pitched, thin, and weak.
reel – (1) The spool onto which magnetic recording tape is wound. Reels come in diameters of 3 inches, 5 inches, 7 inches, 10½ inches, and 14 inches for use with various size tapes. (See magnetic recording tape for information on tape widths.) (2) The spool onto which moviefilm is wound. Originally a standard 35-mm film reel was 1,000 feet (305 m), which ran approximately 11 minutes. Today a standard reel is 2,000 feet (610 m). See also film footage. (3) The amount of magnetic tape or movie film that fits on one reel.
reference level – (1) The level used as a basis of comparison when designating the level of an audio signal, usually measured in decibels or volume units. Also known as a reference signal level. (2) The power level used as a reference when calculating ratios for decibels. Also called a reference point.
reference track – a track on a commercially-released compact disc used for comparison when mixing. The goal is not to copy the sound, but to match the frequency response, dynamics, feel, and energy of the reference track. The reference track should be in the same style as the track being mixed.
reflection shield – a semi-circular device made of acoustic-absorbing material that attaches to a microphone stand and surrounds the microphone in order to block or absorbsound waves preventing them from reflecting off nearby walls. It is designed to be used in rooms with insufficient acoustic treatment. Although some experts say they are helpful, others say they provide minimal improvement, since most of the reflections reaching the microphone come from behind the vocalist. Also known as isolation shield, sound shield, vocal shield, or reflection filter.
refraction – the splitting of a sound wave into various frequency bands as it passes from one medium into another, such as from air into water, similar to the way a prism disperses light into the colors of the rainbow.
refresh rate – the rate at which a video display image is refreshed, usually expressed in hertz (Hz) or frames per second (fps). A higher refesh rates produces a smoother image. In countries with a power line frequency of 60 Hz, the refresh rate is 24, 30, or a multiple of 60. In countries with a 50-Hz power frequency, the refresh rate will be 25 or a multiple of 50. See also frame rate and field rate.
regenerating timecode – a timecode that is created by reading the code from the master tape and creating a perfect electronic duplicate of it when copying a video or audio tape that has a SMPTE timecode. The new code is created by an external device and is necessary to ensure that the copy is free of timing errors and dropouts.
regeneration – (1) Feeding the ouput from a delay device back into the input creating multiple echoes. (2) The control on a delay device that determines the amount of signal fed back to the input. Also called feedback or recirculation.
region – (1) An audio clip. (2) In REAPER a location similar to a marker that is used to identify a section of a song (such as intro, verse, or chorus), but unlike markers, regions have both a beginning and ending point for each section and are displayed in the regions band of the timeline. Markers are displayed in the marker ribbon.
register – (1) The range of pitches of a voice or instrument. See also tessitura. (2) A set of pipes of one length on an organ, responsible for a specific octave or timbre.
registered jacks – a standardized network interface specifying both the type of connector and the wiring configuaration used in telecommunications and data equipment. Most registered jacks use the modular connector, but other connector types are used. The configurations are denoted by their RJ designations. See also RJ11, RJ12, and RJ45. For a list of RJ numbers and their configurations, see Wikipedia: Registered jack.
relap – to do a very fine grain sanding or polishing on a tape recorderhead to restore it to good working condition after it has been worn down.
relative grid mode – an editing mode in a DAW that allows movement and alignment of clips to specific points along a grid with user-defined increments while allowing the clips to maintain an offset relative to the grid point. See also absolute grid mode.
relative measurement – the measurement of a change or difference in a quantity or in relation to another item or device. For example, the gain of an amplifier is the change in voltage from the input to output. In contract, an absolute measurement is the measurement of a quantitiy starting from zero or a known starting point. For example, the measurment of a voltage is the number of volts above zero volts, while the height of a building is the distance from street level (the starting point) to the top of the building.
release – (1) The amount of time it takes for a sound to go from the sustain level back to silence. The fourth of the four segments of an ADSR envelope. (2) The time it takes for the gain of a compressor to return to normal after the signal drops below the threshold. Also called release time. (3) To introduce a recording and make it available to the public for sale, such as a CD release.
release print – a copy of a film that is distributed to a movie theaters for exhibition. Sometimes called a film print.
remix – (1) To mix a previously mixed song to create a variant version, sometimes adding additional tracks or samples. (2) A new version of a song that has been remixed. (3)(Rarely used) To mix or mixdown, i. e. combining several tracks into one stereo track.
remote – (1) A recording session that takes place outside the studio. See remote recording. (2) Activated without using the control panel on a device, as in remote control. (3) Controlled from a distance using a keypad, a transmitter, or other device.(4) A device used to control from a distance the operation of an appliance or machine, such as a television set or DVD player. Also called a remote control.
remote control (RC) – (1) The control of the operation or performance of a device from a distance, such as controlling a DAW from a smart phone. (2) A device used to control from a distance the operation of an appliance or machine, such as a television set or DVD player. Also called a remote.
remote integration(REMI) – a television production model which uses automation, remote cameras (especially PTZ cameras), and other devicess to capture sporting events and other programs at a remote location, but that is mixed and controlled in the broadcaststudio.
remote recording – a recording made outside the recording studio, such as a live performance at a concert. Also called on-location recording.
render – (1) To change an audio file in a non-realtime process by applying the attributes defined in a plug-in or software program. This method is in contrast to a realtime procedure in which the attributes are applied to the audio file as it is being played without changing the file. (2) To consolidate several clips on a track into a single contiguous file. Other DAWs refer to this as consolidate, merge, or glue.
repeat – (1) A section of music that is to be played more than once, as indicated by a repeat mark. (2) In a delay effect, a single discrete echo or repetition of the sound.
repeat echo – an echo effect with discrete repeats of the sound. It is created using a delay unit with a long delay time and feedback. Sometimes called a space echo.
repeat mark – a musical symbol consisting of two vertical lines preceded by two dots, one over the other, that indicates that the section is to be repeated, either from the beginning of the piece or from the beginning repeat mark. Also called repeat sign.
repertoire – (1) Music which a musician or musical group knows and is performance-ready. (2) The catalog of songs or performers that a publisher or record label has on its roster.
replace edit – a digital audio edit in which new audio material is pasted into a track to replace the existing audio material. See also three-point edit and four-point edit.
replacement dialog – dialog recorded after a film or video has been shot to replace poorly recorded sound or to change the dialog. See also ADR.
replication – a method of manufacturing compact discs in which a glass master is created from which multiple copies can be stamped. The stamper presses the pits (representing the data) into a polycarbonate disc onto which a reflective layer of an aluminum alloy is fixed. The entire disc is then coated with a lacquer. The finished product is an audio CD (not a CD-R) just like you buy in the record stores. This process is used for large quantities (typically 300 to 500 copies or more), as opposed to duplication, which is used for smaller quantities.
reproduce – (1) To create music or other audio from a recording or other storage device. (2) To playback audio that has been previously recorded. (3) To make one or more copies of a recording, file, or other item.
reproduction – (1) The process of creating music or other audio from a recording or other storage device. (2) Playing back audio that has been previously recorded. (3) The process of making one or more copies of a recording, file, or other item.
residual-current device (RCD) – a British term for a device designed to protect from electrical shock by tripping a circuit breaker when a difference in current occurs between the “hot” and neutral wires, indicating a short or abnormal diversion of current. In the US it is called a ground fault circuit interrupter (GFCI) or a ground fault interrupter (GFI).
residual flux density (Br) – the amount of magnetism left in a magnetic medium after an applied magnetic field is removed, measured in teslas (T), which is equivalent to webers per square meter (Wb/m2). Also called residual induction, residual magnetization, or residual magnetism. See also retentivity and remanence.
resistive opto-isolator (RO) – an optoelectronic device consisting of a light source and detector, that are optically coupled and electrically isolated from one another. The light source is usually a light-emitting diode (LED), incandescent lamp, or neon lamp, and the detector is a photocell. The RO acts like a variable resistor that is controlled by the current flowing through the light source. ROs are used in some audio equipment, guitar amplifiers, and analog synthesizers because of their good electrical isolation, low signal distortion, and ease of circuit design. Also called a photoresistive opto-isolator, analog opto-isolator, or lamp-coupled photocell.
resistivity – the property of a given material that indicates how strongly it opposes the flow of electric current. It is the reciprocal of electrical conductivity. Resistivity is represented by the Greek letter ρ (rho). The SI unit of resistivity is the ohm-meter (Ω-m), but the ohm-centimeter (Ω-cm) is sometimes used. Resistance (R) can be calculated for a material using the equation R = ρ × L/A, where ρ is resistivity, L is the length, and A is the cross-sectional area. Also called electrical resistivity, specific resistance, or volume resistivity.
resolution – (1) A measure of the detail or fineness of a system or device. In film photography, resolution (called image resolution) is usually expressed in lines per inch. In digital photography, resolution is often expressed in megapixels, the total number of pixels in the image. For a digital television screen, computer monitor, or other display device, resolution (called display resolution or graphic display resolution) is usually expressed as the number of pixels in each direction, such as 1920 × 1080. Printers express resolution (called print resolution or printing resolution) as the number of individual dots that a printer can produce within a unit distance, such as dots per inch (dpi). For digital audio, resolution is measured by bit depth, the number of bits used to express amplitude in sampled audio. However, resolution can also be expressed in the time domain. A CD with a sample rate of 44.1 kHz has a resolution of 1/44,100 or about 0.023 milliseconds. (2) In music, the movement of a note or chord from dissonance (an unstable sound) to a consonance (a more final or stable sounding one).
resonant – (1) Tending to vibrate or oscillate at a particular frequency when excited by an external source and to continue to vibrate after the excitation is removed. (2) A descriptive term for a sound that is deep and clear, especially used when describing a voice. (3) A descriptive term for a sound that continues to ring or linger.
resonant frequency (ω) – the frequency at which an object tends to vibrate with a greater intensity than at other frequencies. Also called natural frequency. See also resonance.
resonant head – the head on the side of the drum that is not struck by the drummer, designed to enhance the tone of the drum when the batter head on the opposite side of the drum is struck. Resonant heads are typically used on snare drums, but toms and kick drums may or may not have them.
resonator guitar – an acoustic guitar that enhances the sound by resonating the string vibrations using one or more spun metal cones. Resonator guitars were originally created to be louder than regular acoustic guitars, which were hard to hear in dance orchestras that had horns and percussion. Even after amplified guitars solved this problem, they continued to be used because of their unique sound, especially in blues and bluegrass music. There are two main styles of resonator guitars: (a) square-necked guitars played like lap steel guitars and (b) round-necked guitars played like conventional acoustic guitars. There are three main resonator designs: (a) the tricone, having three metal cones, designed by the National String Instrument Corporation, (b) the single cone "biscuit" design also by National, and (c) the single inverted-cone design (called a “spider bridge”) by Dobro. Resonator guitars are often played using metalbars or slides (“bottlenecks”) made of metal, glass, or ceramic. Also called a resophonic guitar.
rest – a period of silence in a piece of music, indicated by a symbol denoting the length of the pause. Each rest symbol corresponds to a particular note value. For example, a half rest is the same length as a half note, a quarter rest is as long as a quarter note, etc.
reverb drip – a very heavy reverberation often used with surf guitar music, played in a stacatto style with a very fast reverb that almost sounds like a delay. Reverb drip was originally produced using standalone Fenderreverb tank and then later as part of their amplifiers.
reverberation room – a large room with sound-reflective surfaces designed to produce a uniform, diffuse distribution of acoustic energy in random directions for use in acoustic research and design. These rooms usually use a broadband sound source, such as white noise or pink noise, so that the sound field contains acoustic energy across the whole audible spectrum. They are used for microphone calibration, measurement of the absorption coefficients of various materials, and other acoustic measuremensts. Also called a reverberation chamber.
reverberation time – the amount of time (in seconds) it takes for a reverberation to decay to 60 dB below the original sound pressure level (SPL) after the original sound has stopped. It is designated as RT60, RT-60, or RT60. The decay rate depends on the amount of sound absorption in the room, the room geometry, and the frequency of the sound. Reverberation time, designated as T30, RT30, or RT30 is based on a straight line curve fit between the -5 dB and -35 dB points on the Schroeder curve, extrapolated to 60 dB to be consistent with the RT60. Early-decay time (EDT) is based on a straight-line curve fit between the 0 dB and -10 dB points on the Schroeder curve, also extrapolated to 60 dB of decay. A strong direct field produces an EDT that has a steeper slope than the RT30 curve, which is desirable for increased speech intelligibility and music clarity. Reverberation times vary with frequency as shown in the Table 1 below. Optimum reverberation times depend on the program material, as shown in Table 2. Called reverb time for short. See also Sabine formula, Fitzroy formula and Eyring formula.
reverb tank – an electromechanical device consisting of a set of springs and associated electronics mounted in a metal box to create artificial reverberation (spring reverb). These units were developed originally in 1939 by Laurens Hammond for use in his organs, but Hammond began supplying them to Fender to be sold as a standalone unit beginning in 1961. In 1963, Fender began including them in their guitar amplifiers.
reverse echo – a special effect in which an echo precedes the sound that caused it, increasing from silence into the original sound. This effect is created in the same way as preverb. Also called backwards echo or reverse regeneration.
ReWire – a mechanism developed by Steinberg and Propellerhead that allows various audio applications to communicate and interact with one another using MIDI.
REX file – a proprietary audio file format for sample loops developed by Propellerhead. It is one of the most popular and widely-supported loop formats used in many sequencers and digital audio workstations. REX loops can be timestretched without disturbing the original sound. The REX name comes from ReCycle EXport because these files are generated by Propellerhead's ReCycle looping utility.
RGB – Red-Green-Blue. The system used for representing the colors on a computerdisplay. By combining red, green, and blue in various proportions just about any color in the visible spectrum can be displayed.
RGBHV – Red-Green-Blue-Horizontal-sync-Vertical sync. A five-wire cable carrying the red, green, and blue video signals, as well as the horizontal and vertical sync signals on separate conductors, used to connect the VGA output of a computer to the component video input of a monitor or video processor.
rheostat – an adjustable device used to control an electric current by varying the resistance, usually consisting of a coil of wire with a terminal at one end and a sliding contact that moves along the coil to tap off the current.
rhythm – the combination and variation of beat, tempo, and meter that defines the character of a piece of music other than the melody.
rhythm guitar – a guitar that provides all or part of the rhythmic beat for singers or other instruments and/or provides all or part of the chords. Rhythm guitars are usually used with bands or groups playing within the acoustic, country, blues, rock, and other genres. The rhythm guitar is sometimes considered to be part of the rhythm section, along with the bass and drums.
rhythm section – (1) The instruments in a band or orchestra that establish the rhythm of a song rather than harmony or melody, such as drums, percussion, and bass. Also called rhythm instruments. (2) The group of players in a band or orchestra that play such instruments.
RIAA curve – an equalization curve established by the RIAA for use in the production of vinyl recordings to minimize surface noise. High frequencies are boosted and low frequencies are decreased during recording. The opposite takes place during playback. This minimizes noise and reduces sytlus travel for low freqencies. This process is called emphasis. The RIAA curve specifies three RC time constants (cutoff frequencies): (1) 3180 μs (50 Hz), (2) 318 μs (500 Hz), and (3) 75 μs (2120 Hz). Also called RIAA equalization or RIAA equalization curve. See also RIAA/IEC curve.
RIAA/IEC curve – an equalization curve similar to the RIAA curve, except it defines one additional time constant. The RIAA/IEC curve RC time constants (cutoff frequencies) are: (1) 7960 μs (20 Hz), (2) 3180 μs (50 Hz), (3) 318 μs (500 Hz), and (4) 75 μs (2120 Hz). Also called RIAA/IEC equalization or RIAA/IEC equalization curve.
RIAA Standard Reference Level – a signal level defined by the RIAA for vinyl records that corresponds to a peak stylusmodulation (sideways) velocity of 5 cm/sec for a 1 kHz sine wave. All vinyl mastering studios calibrate their equipment to this level using test equipment and test recordings.
RIAJ – Recording Industry Association of Japan. An industry trade group of Japanese corporations involved the music industry. Founded in 1942 as the Japan Phonogram Record Cultural Association (JPRCA), it adopted its current name in 1969.
ribbon loudspeaker – a type of loudspeaker that consists of a very thin corrugated ribbon made of metal or metal-coated plastic, that is suspended in a magnetic field, similar to a ribbon microphone. An audio signal is applied to the ribbon, causing it to move producing sound. Because the ribbon has very little mass, it can accelerate very quickly, resulting in very good high-frequencyresponse. However, they have poor low-frequency response, so they are most commonly used as tweeters. Ribbon drivers usually require very powerful magnets, which makes them more expensive. Because ribbons have a very low resistance that most amplifiers cannot drive directly, a step-down transformer is often used, which also adds to the cost. Ribbon speakers are typically very fragile and can easily be destoyed by a puff of air. Planar magnetic speakers are sometimes called ribbons, but they are not really ribbon speakers.
ribbon microphone – a type of dynamic microphone that uses a very thin corrugated ribbon made of metal or metal-coated plastic, that is suspended in a magnetic field. When sound waves cause the ribbon to vibrate, an electrical signal is created. Ribbon mics are usually more fragile than other designs, but are often chosen because of the warmth and smoothness they impart.
rich – (1) A descriptive term for a sound that has an even distribution of frequencies, especially the lower frequencies. See also full. (2) Having a special type of distortion made of even-order harmonics created by certain types of effects processors.
rights holder – a person or legal entity that has exclusive rights to a protected copyright, trademark, or patent, including the related rights of producers, performers, and broadcasters. A rights holder may license all or a portion of a protected work in accordance with international legal and licensing laws, and they control the use of these exclusive rights, including reproduction and distribution, with certain limitations and exceptions. If a protected work is used without permission, the rights holder may pursue legal action against the unauthorized user. Sometimes called right holder.
rim – a wood or metal ring that holds the drumhead onto the drum shell and contains holes through which tension rods go and screw into the lugs, used to tighten and adjust the tension of the drumhead. Also called a counter hoop, drum hoop,, or hoop..
ring connector – a round, flat connector with a hole through which a screw or bolt is inserted and tightened to make a connection. Compare with a spade connector. Also called ring terminal.
ringing – (1) The continuation of a signal or vibration after the input signal has stopped. Low frequency ringing is called hangover. (2) A type of distortion that occurs as spurious oscillating signals near transients. It is called “ringing” because the output signal oscillates and slowly fades near the transient, similar to a bell being struck. Pre-ringing (or pre-echoes) occur before a transient, a phenomenon that does not occur in nature. Post-ringing occurs after a transient. Minimization of such ringing artifacts is one criterion in filter design. With filters, the phenomenon is sometimes called ripple.
ringing out a room – the process of eliminating problem frequencies that are prone to cause feedback in a performance venue. One method involves sending pink noise through the speakers and then increasing the microphone levels until feedback occurs. Sometimes called tuning the system or tuning the room, although the latter term is technically incorrect.
ring modulator – a device used to create electronic music by using the sum and difference tones of two input signals producing a large number of harmonics.
Ringo Starr drum-miking technique – a two-microphonedrum-miking technique that was used on most of the Beatles recordings. One microphone is placed about a foot or less from the front of the kick drum at about the height of the beater and aimed at the beater. The second is an overhead mic that is placed over the center of the kit just above the head of the drummer. This method was used for mono recordings, and both mics were usually recorded on a single track. This setup works best for small kits like those used in the 1960s.
rip – to convert audio or video files from one format to another so that they can be stored in another medium, such as a converting a CD to an MP3 file. Also called grab or digital audio extraction (DAE).
ripple edit – a type of editing that occurs when a new clip is inserted, or an existing clip is deleted, the remaining material is adjusted to fit. The change ripples through the rest of the material as the remaining clips slide apart to make room for the new clip or slide together to fill a gap.
rise time – the time it takes for a signal to increase from one level to another, typically from 10% up to 90% of the maximum value. See also decay time.
ritardando – a musical term indicating that the tempo should be gradually decreased. The opposite of accelerando.
RJ11 – a standard 6-pin modular connection (plug and jack) using 2 wires primarily used to connect telephones, but also used in other electronic devices. See also registered jacks.
RJ12 – a standard 6-pin modular connection (plug and jack) using 6 wires primarily used to connect telephones, but also used in other electronic devices. See also registered jacks.
RJ45 – a standard 8-pin modular connection (plug and jack) using 8 wires primarily used for connecting Ethernet devices. See also registered jacks.
RMM – Recreational Music Making. Making music for the fun of it.
RMS – Root Mean Square. A method of computing an average value by taking the square root of the average of the squares of all the instantaneous values of a signal. It is sometimes called the effective value. Compare with peak value and peak to peak.
RMS meter – a type of sound level meter that visually indicates the RMS of the audio level of a signal. An RMS meter tends to indicate the average audio level, which is more indicative of the loudness of the signal than a peak meter, which is more useful for detecting clipping. Sometimes called an average meter.
Robert Bosch GmbH – a company founded by Robert Bosch in Stuttgart, Germany, in 1886. It is now a multinational engineering, automovtive, and electronics company headquartered in Gerlingen, near Stuttgart, Germany. In 2006, Telex/Electro-Voice was acquired by the Bosch Group and became Bosch Communications Systems.
Robinson-Dadson curves – curves that show loudness as perceived by the human ear for various sound levels and frequencies. These equal loudness curves were developed using subjects in an anechoic room. The Fletcher-Munson curves were developed using subjects with headphones. Equal loudness curves are also called equal loudness contours, phon lines, or isophones.
rock 'n' roll – a type of popular dance music that originated in the 1950s, typically consisting of a heavy beat, basic melodies, simple chord progressions, and played with guitar, bass, and drums. Rock 'n' roll was a fusion of black rhythm and blues and white country music. The words “rock” and “roll,” which were black slang for sexual intercourse, were first recorded on a record in 1922 with Trixie Smith's “My Man Rocks Me (With One Steady Roll).” Although often credited with doind so, Alan Freed did not coin the phrase rock 'n' roll, he was just the first to apply it to the new genre of music. Sometimes spelled rock and roll. Called rock for short.
RØDE Microphones – an Australian-based designer and manufacturer of microphones, a subsidiary of Freedman Electronics Group, established in Sydney in 1967. In the early 1990s Peter Freedman took over the family business, which had fallen on hard times, and began importing Chinese microphones, which he repaired and modified. Sales took off like “a rat up a drain pipe,” which led to the unofficial nickname for his microphone as the “Rodent-1.” They morphed that name into the RODE NT-1. Freedman replaced the “O” with the “Ø” character in recognition of his Scandinavian heritage creating the new company name RØDE. (In Danish and Norwegian røde is the plural of rød which means red.) He soon moved the manufacturing to Australia, which greatly helped to improve product quality, and made RØDE a subsidiary of Freedman.
RoHS – Restriction of Hazardous Substances Directive, short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment. A directive adopted in February 2003 by the European Union that became effective on July 1, 2006, (made law and required to be enforced in each member state) that restricts the use of six hazardous materials in the manufacture of certain electronic and electrical equipment, with some exceptions. Four additional materials were added in 2015. The list includes lead, mercury. cadmium, hexavalent chromium (Cr+6), polybrominated biphenyls (PBB), polybrominated diphenyl ether (PBDE), bis(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and diisobutyl phthalate (DIBP). One detrimental side effect has been that the use of lead-free solder has led to the premature demise of some electronic devices.
Roland Corporation – Rorando Kabushiki Kaisha. A company founded in Osaka, Japan, in 1972, that manufactures and markets synthesizers, electronic keyboards, drum machines, guitars, recording equipment, and software. Its headquarters were relocated to Hamamatsu in 2005. In 2014, Roland Corporation was bought out by Roland's then CEO, Junichi Miki.
Roland TR-808 Rhythm Composer – a programmable drum machine, introduced by the Roland Corporation in 1980. TR stood for Transistor Rhythm. Like most early drum machines, it did not sound exactly like real drums, but it was one of the earliest affordable drum machines costing much less than the digital samplers available at the time. TR-808s frequently were used by recording studios in the 1980s to provide rhythms to be used on demos for musicians. Called 808 for short.
rolloff filter – (1) A filter that reduces the output as the frequency increases. (2) A circuit that attenuates a signal that is above (lowpass) or below (highpass) a specified frequency. Also spelled as the less-preferred roll off filter.
Roman numeral analysis – using Roman numerals to represent chords, where Roman numerals (I, II, III, IV, ...) indicate the scale degree (first, second, third, fourth, ...) of the root note of the chord. For example, V is used to indicate the chord based on the fifth degree of a scale. Usually, uppercase Roman numerals, such as I, IV, and V, represent major chords while lowercase Roman numerals, such as i, iv, and v, represent minor chords. The use of Roman numerals allow musicians to quickly determine the progression of chords in a song. Because Roman numeral designations are independent of the key, chord progressions can be transposed easily to any key. For example, the standard twelve bar blues progression is indicated by the Roman numerals I, IV, and V, although it is sometimes written I7, IV7, and V7, because the blues progression is often based on dominantseventh chords. In the key of C, the chords would be C7, F7, and G7. The same progression in the key of A would be A7, D7, and E7. In addition to using a superscript 7 to indicate seventh chords, a superscript o is used to indicate diminished triads and a superscript + is used for augmented triads. In some notations, all roman numerals are in caps, but minor chords are indicated by a lower case m. Other symbols are sometimes used for other types of chords. See also Nashville Number System.
room acoustics simulation – software that attempts to replicate the acoustic behaviour of sound within a given enclosed space. Also called room simulation, room acoustics modelling, and acoustics modelling.
room criteria (RC) – a system used for rating background noise in a building, measruig sound pressure levels (SPL) over the frequency range of 16 Hz to 4000 Hz. This system uses a two-step process: (a) determining the mid-frequency average level and (b) determining the perceived balance between high and low frequency sound. See also noise criteria (NC), noise rating (NR), and balanced noise criteria (NCB).
room equalization – the modification of the frequency response of signals sent to monitors to compensate for the acoustics of the room. Sometimes called dereverberation, room correction or room compensation. When it is done using software, it is sometimes called digital room correction. See also room mode and Room EQ Wizard.
room-in-room effect – the effect that occurs when sound is played back through loudspeakers that includes the reverberation that occurred during recording as well that reverberation that occurs in the playback room.
room microphone – a microphone set up at some distance from a sound source to capture the natural ambience of the room. Sometimes called an ambient microphone
room miking – the process of setting up a room microphone at some distance from a sound source to capture the natural ambience of the room. Sometimes called an ambient miking
room modes – the resonant frequencies that occur in a room caused by standing waves that make certain frequencies, mainly in the range of 20 Hz to 200 Hz, sound louder than others. These frequencies are related to one or more of the dimensions of the room or a divisor of those dimensions. Room modes occur in three types: (a) axial mode – along the axes of a room (front to back, side to side, floor to ceiling), (b) tangential mode – any two pairs of opposite surfaces, and (c) oblique mode – the product of the reflections of all six surfaces. Also called eigentones, standing wave frequencies, room resonances, or modes for short. See also frequency zones.
room ratios (RR) – the ratios of the dimensions of rectangular rooms that create the fewest problems (most uniform distribution) of low-frequency room modes. There is no standard agreement as to what these ratios should be. Some people say that a ratio of height to width to length of 1:1.6:2.6 is considered to have “perfect” acoustics. (Sound engineers frequently use the ratio of 0.62:1:1.62.) It is claimed that no matter where you stand in such a room, the sound will be balanced and natural, and there is little interference from standing waves and essentially no ringing. Researchers on this topic included L. Louden, L. W. Sepmeyer, Philip M. Morse, and Richard H. Bolt. In 1965 Sepmeyer published three sets of ratios: (a) 1:1.14:1.39, (b) 1:1.28:1.54, and (c) 1:1.6:2.33. In 1971, Louden published several ratios, the most often used was 1:1.4:1.9. See also the golden ratio.
root – the lowest note of a chord, which usually gives the chord its name. For example, C is the root of the chord of C (C, E, and G). If the root is not the lowest note, the triad is said to be inverted. See also tonic.
rotary encoder – a device that converts rotation or movement around a shaft into digital code, such as pan or EQ adjustments. There two types of rotary encoders: absolute and incremental (relative). The output of an absolute encoder is indicated by the position of the shaft. The output of an incremental encoder is indicated by the change in position around the shaft. Also called a shaft encoder.
rotary equalizer – a multibandequalizer that uses rotary controls for adjusting the parameters.
rotational speed – the speed at which an object rotates around it axis per unit time, usually specified as revolutions per minute (rpm) or revolutions per second (rps). Also called speed of revolution. See also angular frequency and angular velocity.
rotation point – the point in a compressor or expander above or below which the output signal level is affected.
RPG Diffusor Systems, Inc. – a company founded in the early 1980s by Peter D'Antonio, that designs and manufactures acoustic products. It is located in Upper Marlboro, MD.
rpm – Revolutions per Minute. The measure of the frequency of a rotation or the number of turns completed in one minute around a fixed axis. It is used as a measure of rotational speed of things such as records, hard disks, and compact discs. Records generally have rotational speeds of 78, 45, or 33⅓-rpm. It is also indicated as RPM, rev/min, r/min, or r-min‑1), with r/min being the recommended symbol, but is rarely used outside scientific writings.
RS – Recommended Standard. A series of standards issued by the EIA, such as RS-232, the standard for a serial interface.
RS-232 – the recommended standard for a serial interface.
RTAS – Real Time AudioSuite™. This was the plug-in architecture used by Avid for Pro Tools. RTAS uses the host computer for processing in realtime whereas TDM uses dedicated DSP on hardware cards for processing. Both RTAS and TDM are being phased out, being replaced by AAX.
rub and buzz – a slang term for manufacturing defects that create noises caused by rubbing and buzzing or due to loose particles, especially in loudspeakers.
rubato – (1) In music, having the expressive and rhythmic freedom to slightly speed up and slow down the tempo of a section of music at the discretion of the performer. Sometimes called tempo rubato. (2) A rubato phrase or passage. (3) A rubato performance.
ruler – a ribbon that usually runs across the top of a DAW that displays a variety of information. The number of rulers and the content vary with the DAW. For example, there are two categories of rulers in Pro Tools: timebase and conductor. Timebase rulers provide the timeline in several different formats: (a) minutes and seconds [called a time display ruler in some DAWs], (b) bars and beats for music [called a bar ruler in some DAWs], (c) SMPTE timecode in H:M:S:F for video [called a SMPTE ruler by some], and (d) feet and frames for film. Timebase rulers can be sample-based time (absolute time) or tick-based time (relative time). For example, the minutes:seconds ruler measures absolute time, while the Bars|Beats ruler measures relative time. Conductor rulers display a variety of information that can affect or control the timebase. The meter ruler indicates the number of beats in a bar, while the tempo ruler indicates the number of beats per minute, as well as any changes in meter and tempo within the session. Tempo and meter events affect the timing of tick-based tracks and provide the tempo and meter map for the bar and beat grid and the click track. The key signature ruler indicates changes in key, which will affect MIDI notes when transposing. The chord symbols ruler indicates chords. The marker ruler shows memory locations (markers) and sections of the song. Also called bands or ribbons in some DAWs.
rumble – (1) A low-frequencynoise caused by the mechanical vibration of equipment such as a turntable or tape transport. (2) A low-frequency noise caused by exterior sounds such traffic and air conditioning.
run-out groove area – the area between the last cut or track on a vinylphonograph record and the label, where the groove is spaced farther apart and the ceases to advance toward the center of the record. Also called run-off groove area, end-groove area, matrix area, or dead wax (slang).
run sheet – a sequential list of scenes, events, and actions used in stage, film, video, television, radio, and audio. The run sheet breaks the program into time segments and lists actions, start and stop times, audio cues, camera directions, etc. During production run sheets are provided to the stage crew, camera crew, and audio crew for cues and references. Also called a running sheet or show sheet.
run through – playing a song before recording starts in order for the engineer to set levels and check sound quality. Also called a run down.
Rupert Neve Designs, LLC – a company founded by Rupert Neve and headquartered in Wimberley, Texas, that designs and builds high-end audio equipment for the recording studio. It began in 1975 in the UK as ARN Consultants when Neve left Neve Electronics. In 1994, Neve moved to Wimberley, Texas, and in 2002, the company became a US corporation, ARN Consultants, LLC. In 2005, it changed its name to Rupert Neve Designs, LLC.
rustle track – the audio track that contains the Foleysound effects. This term is used on east coast. On the west coast, it is called a cloth track. These names are derived from the rustling of clothing.
rute – a beater for drums, usually made of a bundle of thin canes, twigs, or wooden dowels attached to a handle. Some have a band that can be moved to adjust the tension on the bundle, in order to alter the tone produced by the rute. It is used to play various drums, including the snare and bass drum. It is pronounced “root-uh.” Also spelled ruthe, which is German for “rod.” Also called a rute stick.
Note: We believe this is the largest dictionary (glossary) of terms specific to usage within the recording industry that is currently available on the internet, with more than 8,300 entries, nearly 600 illustrations, and dozens of tables. Some of the terms have different or additional meanings in other situations, especially within the electronic, automotive, scientific, and computer industries. Of necessity there are obvious overlaps into other fields such as music, electronics, and computers, but such excursions are limited to information deemed pertinent to the knowledge required to operate and/or participate effectively in the workings of a recording studio. Also included are terms related to sound reinforcement (live performances) including wireless microphone technology because a working knowledge of that terminology is necessary for recording at live performance venues. Because recording studios also record audio for video and motion pictures (films), some terminology from those fields is included. Some scientific terms are included because they help explain studio terminology. For example, electromagnetism explains how microphones, loudspeakers, and guitar pickups work. Knowledge of radio waves and the radio frequency spectrum is needed to explain wireless devices. Any trademarks or trade names mentioned belong to their respective owners. The information contained in this dictionary is believed to be accurate at the time of publication. This information is subject to change without notice. The information was obtained from and cross-checked with a variety of sources that are believed to be reliable. However, Los Senderos Studio, LLC does not guarantee the accuracy or completeness of the information contained herein. Please contact us to report any errors, omissions, discrepancies, or broken links. Los Senderos Studio shall not be responsible for any consequences or damages arising out of the use of this information. Nothing in this glossary should be interpreted as legal advice. For a glossary providing information on legal and business matters for musicians, we suggest you consult Musicians Business Dictionary.
A note on alphabetical order: The terms in this glossary are alphabetical without regard to spaces and punctuation. For example, AM Radio follows amplitude. While this may seem to be at odds with other conventions, it eliminates confusion with words such as pickup, which is sometimes written as pick up or pick-up. In addition, all symbols such as &, -, or / are ignored. The entries on the number page (0-9) are listed in increasing value within each digit. For example, all of the entries beginning with 1 are listed before those starting with 2. For Greek letters (α-ω), the entries are in Greek alphabetical order.