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Clean signal, followed by different versions of reverberation (with longer and longer decay times).
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Reverberation is the persistence of sound in a particular space after the original sound is produced.[1] A reverberation, or reverb, is created when a sound is produced in an enclosed space causing a large number of echoes to build up and then slowly decay as the sound is absorbed by the walls and air.[2] This is most noticeable when the sound source stops but the reflections continue, decreasing in amplitude, until they can no longer be heard. The length of this sound decay, or reverberation time, receives special consideration in the architectural design of large chambers, which need to have specific reverberation times to achieve optimum performance for their intended activity.[3] In comparison to a distinct echo that is 50 to 100 ms after the initial sound, reverberation is many thousands of echoes that arrive in very quick succession (.01 – 1 ms between echoes). As time passes, the volume of the many echoes is reduced until the echoes cannot be heard at all.
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[edit] Reverberation time
RT60 is the time required for reflections of a direct sound to decay by 60 dB below the level of the direct sound. Reverberation time is frequently stated as a single value however it can be measured as a wide band signal (20 Hz to 20kHz) or more precisely in narrow bands (one octave, 1/3 octave, 1/6 octave, etc.). Typically, the reverb time measured in narrow bands will differ depending on the frequency band being measured. It is usually helpful to know what range of frequencies are being described by a reverberation time measurement.
In the late 19th century, Wallace Clement Sabine started experiments at Harvard University to investigate the impact of absorption on the reverberation time. Using a portable wind chest and organ pipes as a sound source, a stopwatch and his ears, he measured the time from interruption of the source to inaudibility (roughly 60 dB). He found that the reverberation time is proportional to the dimensions of room and inversely proportional to the amount of absorption present.
The optimum reverberation time for a space in which music is played depends on the type of music that is to be played in the space. Rooms used for speech typically need a shorter reverberation time so that speech can be understood more clearly. If the reflected sound from one syllable is still heard when the next syllable is spoken, it may be difficult to understand what was said.[4] "Cat", "Cab", and "Cap" may all sound very similar. If on the other hand the reverberation time is too short, tonal balance and loudness may suffer. Reverberation effects are often used in studios to add depth to sounds. Reverberation changes the perceived harmonic structure of a note, but does not alter the pitch.
Basic factors that affect a room's reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect this reverberation time, including people and their belongings.
Sabine equation [link]
Sabine's reverberation equation was developed in the late 1890s in an empirical fashion. He established a relationship between the RT60 of a room, its volume, and its total absorption (in sabins). This is given by the equation:
- Failed to parse (Missing texvc executable; please see math/README to configure.): RT_{60} = \frac{4 \ln 10^6}{c} \frac{V}{Sa} \approx 0.1611\,\mathrm{m}^{-1} \frac{V}{Sa}
.
where Failed to parse (Missing texvc executable; please see math/README to configure.): c
is a number that relates to the speed of sound in the room, Failed to parse (Missing texvc executable; please see math/README to configure.): V is the volume of the room in m³, Failed to parse (Missing texvc executable; please see math/README to configure.): S total surface area of room in m², Failed to parse (Missing texvc executable; please see math/README to configure.): a is the average absorption coefficient of room surfaces, and the product Failed to parse (Missing texvc executable; please see math/README to configure.): Sa is the total absorption in sabins.
The total absorption in sabins (and hence reverberation time) generally changes depending on frequency (which is defined by the acoustic properties of the space). The equation does not take into account room shape or losses from the sound travelling through the air (important in larger spaces). Most rooms absorb less sound energy in the lower frequency ranges resulting in longer reverb times at lower frequencies.
The reverberation time RT60 and the volume V of the room have great influence on the critical distance dc (conditional equation):
- Failed to parse (Missing texvc executable; please see math/README to configure.): d_\mathrm{c} \approx 0{.}057 \cdot \sqrt \frac{V}{RT_{60}}
where critical distance Failed to parse (Missing texvc executable; please see math/README to configure.): d_c
is measured in meters, volume Failed to parse (Missing texvc executable; please see math/README to configure.): V
is measured in m³, and reverberation time Failed to parse (Missing texvc executable; please see math/README to configure.): RT_{60}
is measured in seconds.
Absorption [link]
The absorption coefficient of a material is a number between 0 and 1 which indicates the proportion of sound which is absorbed by the surface compared to the proportion which is reflected back into the room. A large, fully open window would offer no reflection as any sound reaching it would pass straight out and no sound would be reflected. This would have an absorption coefficient of 1. Conversely, a thick, smooth painted concrete ceiling would be the acoustic equivalent of a mirror, and would have an absorption coefficient very close to 0.
Measurement of reverberation time [link]
Historically reverberation time could only be measured using a level recorder (a plotting device which graphs the noise level against time on a ribbon of moving paper). A loud noise is produced, and as the sound dies away the trace on the level recorder will show a distinct slope. Analysis of this slope reveals the measured reverberation time. Some modern digital sound level meters can carry out this analysis automatically.
Currently several methods exist for measuring reverb time. An impulse can be measured by creating a sufficiently loud noise (which must have a defined cut off point). Impulse noise sources such as a blank pistol shot or balloon burst may be used to measure the impulse response of a room.
Alternatively, a random noise signal such as pink noise or white noise may be generated through a loudspeaker, and then turned off. This is known as the interrupted method, and the measured result is known as the interrupted response.
A two port measurement system can also be used to measure noise introduced into a space and compare it to what is subsequently measured in the space. Consider sound reproduced by a loudspeaker into a room. A recording of the sound in the room can be made and compared to what was sent to the loudspeaker. The two signals can be compared mathematically. This two port measurement system utilizes a Fourier transform to mathematically derive the impulse response of the room. From the impulse response, the reverberation time can be calculated. Using a two port system, allows reverberation time to be measured with signals other than loud impulses. Music or recordings of other sound can be used. This allows measurements to be taken in a room after the audience is present.
Reverberation time is usually stated as a decay time and is measured in seconds. There may or may not be any statement of the frequency band used in the measurement. Decay time is the time it takes the signal to diminish 60 dB below the original sound.
The concept of Reverberation Time implicitly supposes that the decay rate of the sound is exponential, so that the sound level diminishes regularly, at a rate of so many dB per second. It is not often the case in real rooms, depending on the disposition of reflective, dispersive and absorbing surfaces. Moreover, successive measurement of the sound level often yields very different results, as differences in phase in the excitating sound build up in notably different sound waves. In 1964, Manfred R. Schroeder published "A new method of Measuring Reverberation Time" in the Journal of the Acoustical Society of America. He proposed to measure, not the power of the sound, but the energy, by integrating it. This allowed to show the variation in the rate of decay, and to free acousticians from the necessity of averaging many measurements.
Creating reverberation effects [link]
It is often desirable to create a reverberation effect for recorded or live music. A number of systems have been developed to facilitate or simulate reverberation.
Chamber reverberators [link]
The first reverb effects created for recordings used a real physical space as a natural echo chamber. A loudspeaker would play the sound, and then a microphone would pick it up again, including the effects of reverb. Although this is still a common technique, it requires a dedicated soundproofed room, and varying the reverb time is difficult.
Plate reverberators [link]
A plate reverb system uses an electromechanical transducer, similar to the driver in a loudspeaker, to create vibration in a large plate of sheet metal. A pickup captures the vibrations as they bounce across the plate, and the result is output as an audio signal. In the late 1950s, Elektro-Mess-Technik (EMT) introduced the EMT 140;[5] a 600-pound (270 kg) model popular in recording studios, contributing to many hit records such as those recorded by Bill Porter in Nashville's RCA Studio B. Early units had one pickup for mono output, later models featured two pickups for stereo use. The reverb time can be adjusted by a damping pad, made from framed acoustic tiles. The closer the damping pad, the shorter the reverb time. However, the pad never touches the plate. Some units also featured a remote control.
Spring reverberators [link]
A spring reverb system uses a transducer at one end of a spring and a pickup at the other, similar to those used in plate reverbs, to create and capture vibrations within a metal spring. Guitar amplifiers frequently incorporate spring reverbs due to their compact construction and low cost. Spring reverberators were once widely used in semi-professional recording due to their modest cost and small size.
Many musicians have made use of spring reverb units by rocking them back and forth, creating a thundering, crashing sound caused by the springs colliding with each other. The Hammond Organ included an inbuilt spring reverberator, making this a popular effect when used in a rock band.
Digital reverberators [link]
Digital reverberators use various signal processing algorithms in order to create the reverb effect. Since reverberation is essentially caused by a very large number of echoes, simple reverberation algorithms use multiple feedback delay circuits to create a large, decaying series of echoes. More advanced digital reverb generators can simulate the time and frequency domain responses of real rooms (based upon room dimensions, absorption and other properties). In real music halls, the direct sound always arrives at the listener's ear first because it follows the shortest path. Shortly after the direct sound, the reverberant sound arrives. The time between the two is called the "pre-delay."
Convolution reverb [link]
See also [link]
References [link]
- ^ Valente, Michael; Holly Hosford-Dunn, Ross J. Roeser (2008). Audiology. Thieme. pp. 425–426. ISBN 978-1-58890-520-8.
- ^ Lloyd, Llewelyn Southworth (1970). Music and Sound. Ayer Publishing. pp. 169. ISBN 978-0-8369-5188-2.
- ^ Roth, Leland M. (2007). Understanding Architecture. Westview Press. pp. 104–105. ISBN 978-0-8133-9045-1.
- ^ "So why does reverberation affect speech intelligibility?". MC Squared System Design Group, Inc. https://www.mcsquared.com/y-reverb.htm. Retrieved 2008-12-04.
- ^ Eargle, John M. (2005). Handbook of Recording Engineering (4 ed.). Birkhäuser. p. 233. ISBN 0-387-28470-2. https://books.google.com/books?id=00m1SlorUcIC&pg=PA233.
External links [link]
- Reverberation - Hyperphysics
- A database of measured room impulse responses to generate realistic reverberation effects
- Spring Reverb Tanks Explained and Compared
- Download possibility for a calculation software to Reverberation Time
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Reverb (disambiguation)
Reverb may refer to:
Reverberation may refer to:
List of Marvel Comics characters: R
R. U. Reddy
R. U. Reddy (Winthrop Roan, Jr.) is a mutant and a member of the Thunderiders. He first appeared in Captain America #269 (May 1982), and was created by J. M. DeMatteis and Mike Zeck. Winthrop Roan, Jr. was the singer in a rock band known as Ruff Stuff. With Honcho and Wolf, he formed the professional motorcyclist team called Team America, which was eventually known as the Thunderiders. R.U. Reddy is a mutant who shares a mental link with the four other members of the Thunderiders. The five mutants can project their collective physical skills, strength, and knowledge into another person without diminishing their own abilities in any way.
Radion the Atomic Man
Radion the Atomic Man first appeared in Marvel Two-in-One #9 (May 1975), and was created by Steve Gerber, Chris Claremont and Herb Trimpe. Exposure to radioactive isotopes caused Dr. Henri Sorel to mutate into an inhuman being who could generate blasts of nuclear energy, and warped his personality. The Puppet Master agreed to assist Radion in exchange for his help. Radion amplified the radiation in the Puppet Master's clay, enabling him to use Thor to attack the Fantastic Four. When Wundarr the Aquarian arrived to help, he absorbed Radion's powers, causing Radion to flee. Sorel then constructed a suit of armor to contain his energies and protect himself from reaching critical mass. He renamed himself the Ravager and traveled to London. He is also known as the Atom.
Rammstein
Rammstein (German pronunciation: [ˈʁamʃtaɪn]) is a German Neue Deutsche Härte band, formed in 1994 in Berlin. Throughout its existence, Rammstein's six-man lineup has been unchanged—singer Till Lindemann, guitarists Richard Z. Kruspe and Paul H. Landers, bassist Oliver "Ollie" Riedel, drummer Christoph "Doom" Schneider and keyboardist Christian "Flake" Lorenz.
The majority of their songs are in German, but they have also performed songs entirely or partially in other languages including English, Spanish, French, and Russian. Rammstein's award-winning live shows are renowned for their pyrotechnic elements and both on and off-stage theatrics. Rammstein's entire catalogue is published by Universal Music Group.
History
Founding and Herzeleid, 1989–96
In 1989 East German guitarist Richard Z. Kruspe escaped to West Berlin and started the band Orgasm Death Gimmicks. At that time, he was heavily influenced by American music, especially that of rock group Kiss. After the Berlin Wall came down, he moved back home to Schwerin, where Till Lindemann worked as a basket-weaver and played drums in the band First Arsch (loosely translated as "First Ass" or "First Arse"). At this time, Kruspe lived with Oliver Riedel of the Inchtabokatables and Christoph "Doom" Schneider of Die Firma. Kruspe had come to realize that the music he had previously created did not really suit him. He envisioned something that would combine machines as well as the sound of hard guitars. Kruspe, Riedel and Schneider started working together on a new project in 1994. Finding it difficult to write both music and lyrics, Kruspe persuaded Lindemann, whom he had overheard singing while he was working, to join the fledgling group.
Rammstein (song)
"Rammstein" is a song by the German industrial metal band Rammstein. It is the eleventh and final track on their debut album, Herzeleid, and was the first song written by the band. It is about the Ramstein air show disaster. According to an interview with rhythm guitarist Paul Landers, the sound of the main riff of the song is made by him and lead guitarist Richard Kruspe, each playing a similar riff at different octaves (Richard plays the middle and Paul plays the lower). The song was featured in the 1997 David Lynch film Lost Highway.
In the Live aus Berlin performance of the song, lead vocalist Till Lindemann ascends from underneath the stage via a trap door. He wears a burning coat, and special goggles from which a laser beam is projected from one of the lenses. When they performed the song in the 2004–05 Reise, Reise tour, Lindemann no longer wore the flaming jacket, opting instead for dual arm mounted flame throwers.
Rammstein has been a part of every tour setlist since the song's inception, including the Pre-Herzeleid years. The only tour it has not been included in is the tour for Liebe ist für alle da and Made in Germany 1995–2011, although in the last Made in Germany tour/unofficial tour name of the Made in Germany tour Wir halten das Tempo tour, the introduction of the song has been used to tease the audience as they performed the intro with guitar flamethrowers cutting into "Bück Dich", just before the vocals enter and after the Rammstein intro with guitar flamethrowers before "Bück Dich" gets performed, the crowd say Rammstein.
Rammstein discography
The discography of Rammstein, a German Neue Deutsche Härte band, consists of six studio albums, two live albums, and four video albums. Rammstein has also released twenty-five singles, twenty-four of which are accompanied by music videos. The band was formed in the mid-1990s by six musicians from East Berlin and Schwerin: singer Till Lindemann, guitarists Richard Kruspe and Paul Landers, keyboardist Flake Lorenz, bassist Oliver Riedel, and drummer Christoph Schneider.
Rammstein debuted with the single "Du riechst so gut", released on 17 August 1995 in a scented digipack format. A month later, the band issued their first studio album, Herzeleid, which peaked at number six on the German Media Control Charts and remained there for 102 weeks. Before the release of its second studio album, Rammstein issued the single "Engel" is was featured on end credits in the 1997 film Mortal Kombat 2: Annihilation and from in the music video was featured From Dusk Till Dawn, on 1 April 1997. It reached the top three on the German singles chart and was certified gold by the Bundesverband Musikindustrie (BVMI) for the sale of more than 250,000 copies.
