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| {{about||the magazine|Acoustic Guitar (magazine)|the album by Preston Reed|Acoustic Guitar (album)}}
| | Hello, my title is Andrew and my wife doesn't like it at all. Credit authorising is how she tends to make a living. To perform domino is something I really enjoy doing. For many years she's been residing in Kentucky but her spouse desires them to transfer.<br><br>Also visit my website - [http://www.octionx.sinfauganda.co.ug/node/22469 free online tarot card readings] |
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| [[Image:AcousticGuitar.jpg|frame|right|A modern acoustic guitar.]]
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| An '''acoustic guitar''' is a [[guitar]] that uses only acoustic (as opposed to electronic) means to transmit the strings' vibrational energy to the air in order to produce a sound. This typically involves the use of a [[Sound board (music)|sound board]] and a [[sound box]] to amplify the vibrations of the string.
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| The source of sound in an acoustic guitar is the string, which is plucked with the fingers or with a [[plectrum]]. The string vibrates at a fundamental frequency but also creates many harmonics at different frequencies. The frequencies produced depend on string length, mass, and tension. The string causes the soundboard and sound box to vibrate, and as these have their own resonances at certain frequencies, they amplify some string harmonics more strongly than others, hence affecting the timbre produced by the instrument.
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| ==Acoustic properties==
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| The acoustic guitar's soundboard, or top, also has a strong effect on the loudness of the guitar. No [[Amplifier|amplification]] actually occurs in this process, in the sense that no energy is externally added to increase the [[loudness]] of the sound (as would be the case with an electronic amplifier). All the energy is provided by the plucking of the string. But without a soundboard, the string would just "cut" through the air without actually moving it much. The soundboard increases the surface of the vibrating area in a process called [[Impedance_matching#Mechanics|mechanical impedance matching]]. The soundboard can move the air much more easily than the string alone, because it is large and flat. This increases the entire system's energy transfer efficiency, and a much louder sound is emitted.
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| In addition, the acoustic guitar has a hollow body and an additional coupling and resonance effect increases the efficiency of energy transmission in lower frequencies. The air in a guitar's cavity resonates with the vibrational modes of the string and soundboard. At low frequencies, which depend on the size of the box, the chamber acts like a [[Helmholtz resonance|Helmholtz resonator]], increasing or decreasing the volume of the sound again depending on whether the air in the box is moving in phase or out of phase with the strings. When in phase, the sound is increased by about 3 decibels and when in opposing phase, it is decreased about 3 decibels.{{Citation needed|date=March 2012}} As a Helmholtz resonator, the air at the opening is vibrating in or out of phase with the air in the box and in or out of phase with the strings. These resonance interactions attenuate or amplify the sound at different frequencies, boosting or damping various harmonic tones. Ultimately, the cavity air vibrations couple to the outside air through the sound hole<ref>[http://www.phys.unsw.edu.au/music/guitar/guitarintro.html How a guitar works<!-- Bot generated title -->]</ref> (some variants of the acoustic guitar omit this hole, or have <math>f</math> holes, like a [[violin family]] instrument). This coupling is most efficient because here the impedance matching is perfect: it is air pushing air.
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| There are therefore several sound coupling modes in an acoustic guitar: string to soundboard, soundboard to cavity air, and both soundboard and cavity air, to outside air. The back of the guitar will also vibrate to a lesser extent, driven by the air in the cavity. The function of the entire acoustic system is twofold: to color the sound through the generation and amplification of harmonics, and to maximize the coupling of this energy to the surrounding air - which is ultimately what we perceive as loudness of the produced sound. Improved coupling, however, comes at the expense of decay time, since now the string's energy is more efficiently transmitted. An unamplified guitar (one with no soundboard at all) would have a low volume, but the strings would vibrate much longer, like a tuning fork.
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| All these complex air coupling interactions, along with the resonant properties of the panels themselves, are a key reason that different guitars will have different tonal qualities. The sound is a complex mixture of [[harmonics]] that give the guitar its distinctive sound.
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| {{Listen
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| |filename =AcousticGuitarSample.ogg
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| |title =Acoustic Guitar Sample
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| |description =An example of the sounds which an acoustic guitar can create through vibration of its strings. This guitar uses steel strings.
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| }}
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| ==Amplification==
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| [[Image:Pattern on Acoustic Guitar.JPG|thumb|right|230px|Many acoustic guitars incorporate [[rosette (design)|rosettes]] around the [[sound hole]].]]
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| [[Image:Nancy Wilson - Heart - 1978.jpg|right|thumb|alt=Nancy Wilson plays an Adamas-model Ovation guitar|[[Heart (band)|Heart]]{{'s}} [[Nancy Wilson (rock musician)|Nancy Wilson]] ''(pictured)'' plays an Ovation Adamas,<ref>{{harvtxt|Carter|1996|p=127}}
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| </ref> whose parabolic shape reduces feedback and increases volume.]]
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| {{main|Acoustic-electric guitar}}
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| Classical gut-string guitars had little projection, and so were unable to displace banjos until innovations increased their volume.
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| Two important innovations were introduced by the American firm, [[Martin Guitars]]. First, Martin introduced steel strings. Second, Martin increased the area of the guitar top; the popularity of Martin's larger "[[Dreadnought (guitar type)|dreadnought]]" body size amongst acoustic performers is related to the greater sound volume produced. These innovations allowed guitars to compete with and often displace the banjos that had previously dominated jazz bands. The steel-strings increased tension on the neck; for stability, Martin reinforced the neck with a steel [[truss rod]], which became standard in later steel-string guitars.<ref name="DenyerMartin">{{harvtxt|Denyer|1992|pages=44–45}}</ref>
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| An acoustic guitar can be amplified by using various types of pickups or microphones. However, amplification of acoustic guitars had many problems with [[audio feedback]]. In the 1960s, [[Ovation Guitar Company|Ovation]]'s parabolic bowls dramatically reduced feedback, allowing greater amplification of acoustic guitars.<ref name="DenyerOvation">{{harvtxt|Denyer|1992|page=48}}</ref> In the 1970s, Ovation developed thinner sound-boards with carbon-based composites laminating a thin layer of birch, in its Adamas model, which has been viewed as one of the most radical designs in the history of acoustic guitars. The Adamas model dissipated the sound-hole of the traditional soundboard among 22 small sound-holes in the upper chamber of the guitar, yielding greater volume and further reducing feedback during amplification.<ref name="DenyerOvation"/> Another method for reducing feedback is the use of a rubber or plastic disc which fits into the soundhole.
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| The most common type of pickups used for acoustic guitar amplification are piezo and magnetic pickups. [[Piezo pickup]]s are generally mounted under the bridge saddle of the acoustic guitar and can be plugged into a mixer or amplifier. A Piezo pickup made by Baldwin was incorporated in the body of Ovation guitars, rather than attached by drilling through the body;<ref>{{harvtxt|Carter|1996|pp=48–52}}</ref> the combination of the Piezo pickup and parabolic ("roundback") body helped Ovation to lead the market during the 1970s.<ref>DenyerOvation</ref> [[Magnetic pickup]]s are generally mounted in the sound hole of the acoustic guitar and are very similar to those found in electric guitars. An acoustic guitar with pickups for electrical amplification is known as an [[acoustic-electric guitar]].
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| In the 2000s, new types of pickups have been introduced to try to amplify the full sound of these instruments. This includes body sensors such as the Taylor Expression system, and systems that include an internal microphone along with the body sensors or under-the-saddle pickups.{{citation needed|date=February 2013}}
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| == Types ==
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| [[File:Yamaha APX700.jpg|thumb|right|A steel strung Yamaha APX700 electric-acoustic guitar]] | |
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| Historical and modern acoustic guitars are extremely varied in their design and construction, far more so than electric guitars. Some of the most important varieties are the [[classical guitar]] (nylon-stringed), [[steel-string acoustic guitar]] and [[lap steel guitar]]. A more complete list is given below, refer to the individual articles for more specific detail.
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| {{citation needed|date=February 2012}}
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| *'''Nylon/gut stringed guitars''':
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| **Renaissance guitar
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| **[[Baroque guitar]]
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| **[[Romantic guitar]]
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| **[[Classical guitar]], the modern version of the original guitar, with nylon strings
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| **[[Flamenco guitar]]
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| **[[Extended-range classical guitar]]
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| *'''Steel stringed guitars''':
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| **[[Steel-string acoustic guitar]], also known as western, folk or country guitar
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| **[[Twelve string guitar]]
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| **[[Resonator guitar]] (such as the ''[[Dobro]]'')
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| **[[Archtop guitar]]
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| ** [[Selmer guitar|Selmer/Maccaferri (Manouche) guitar]]
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| **[[Battente guitar]]
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| **[[Lap steel guitar]]
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| **[[Parlor guitar|Parlor Guitar]]
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| **[[Lyre-guitar]]
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| **[[Weissenborn]]-style guitar
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| *[[Acoustic bass guitar]]
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| *[[Russian guitar]]
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| *Other variants:
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| **[[Pikasso guitar]]
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| **[[Harp guitar]]
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| **[[Guitjo (six-string)|Banjo guitar]]
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| **[[lute|Guitar lute]]
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| ==Notes==
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| {{Reflist}}
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| ==References==
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| * {{cite book|last=Carter|first=Walter|year=1996|title=The history of the Ovation guitar|editor-first=Jon|editor-last=Eiche|publisher=[[Hal Leonard Corporation]]|series=Musical Instruments Series|location=Milwaukee, Wisconsin|isbn=|edition=first|pages=1–128|id=HL00330187; ISBN 978-0-7935-5876-6; ISBN 0-7935-5876-X (softcover); ISBN 0-7935-5948-0 (hardcover)<!-- Hal Leonard -->|ref=harv}}
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| * {{Cite book
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| | title = The guitar handbook
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| | first = Ralph
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| | last = Denyer
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| | others = Special contributors [[Isaac Guillory]] and <!-- NOT [[Alastair Crawford]] -->Alastair M. Crawford; Foreword by [[Robert Fripp]]
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| | pages =
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| | chapter=
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| | isbn = 0-330-32750-X
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| | location = London and Sydney
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| | publisher = Pan Books
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| | edition= Fully revised and updated
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| | year = 1992
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| }}
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| ==External links==
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| {{commons category|Acoustic guitars}}
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| {{Guitars|Type}}
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| [[Category:Acoustic guitars|*]]
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| [[Category:Rhythm section]]
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