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A sound board, or soundboard, is the surface of a
string instrument
String instruments, stringed instruments, or chordophones are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner.
Musicians play some string instruments by plucking the ...
that the strings vibrate against, usually via some sort of
bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
.
Piano
The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some early pianos used leather). It is played using a keyboa ...
s,
guitar
The guitar is a fretted musical instrument that typically has six strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected stri ...
s,
banjos, and many other stringed instruments incorporate soundboards. The resonant properties of the sound board and the interior of the instrument greatly increase the
loudness
In acoustics, loudness is the subjectivity, subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The rel ...
of the vibrating strings. "The soundboard is probably the most important element of a guitar in terms of its influence on the quality of the instrument's tone ."
[Sloane, Irving (1989). ''Classic Guitar Construction'', p.20. Bold Strummer. . "The sound board is the most important element in the guitar."]
The sound board operates by the principle of
forced vibration. The string gently vibrates the board, and despite their differences in size and composition, makes the board vibrate at exactly the same frequency. This produces the same sound as the string alone, differing only in
timbre
In music, timbre ( ), also known as tone color or tone quality (from psychoacoustics), is the perceived sound quality of a musical note, sound or musical tone, tone. Timbre distinguishes different types of sound production, such as choir voice ...
. The string would produce the same amount of energy without the board present, but the greater surface area of the sound board moves a greater volume of air, which produces a louder sound. "Generally, stiffer boards will give a brighter edge to the sound than softer, more flexible boards....A good, dry sound board has a certain 'live' tone while a poor one will have a relatively dead response," which may be tested during construction by thumping the board and listening for, "brighter, more noticeable ring
ng" as one works the board, "to the appropriate thinness."
Sound boards are traditionally made of wood (see
tonewood
Tonewood refers to specific wood varieties that possess tonal properties that make them good choices for use in woodwind or acoustic stringed instruments.
Varieties of tonewood
As a rough generalization it can be said that stiff-but-light softwood ...
), though other materials are used, such as skin or plastic on instruments in the
banjo family. Wooden sound boards typically have one or more
sound hole
A sound hole is an opening in the body of a stringed musical instrument, usually the upper sound board.
Sound holes have different shapes:
* round in flat-top guitars and traditional bowl-back mandolins;
* F-holes in instruments from the vio ...
s of various shapes. Round, oval, or
F-hole
A sound hole is an opening in the body of a stringed musical instrument, usually the upper sound board.
Sound holes have different shapes:
* round in flat-top guitars and traditional bowl-back mandolins;
* F-holes in instruments from the vi ...
s appear on many plucked instruments, such as
guitar
The guitar is a fretted musical instrument that typically has six strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected stri ...
s and
mandolin
A mandolin ( it, mandolino ; literally "small mandola") is a stringed musical instrument in the lute family and is generally plucked with a pick. It most commonly has four courses of doubled strings tuned in unison, thus giving a total of 8 ...
s.
F-hole
A sound hole is an opening in the body of a stringed musical instrument, usually the upper sound board.
Sound holes have different shapes:
* round in flat-top guitars and traditional bowl-back mandolins;
* F-holes in instruments from the vi ...
s are usual in
violin
The violin, sometimes known as a ''fiddle'', is a wooden chordophone (string instrument) in the violin family. Most violins have a hollow wooden body. It is the smallest and thus highest-pitched instrument (soprano) in the family in regular ...
family instruments.
Lute
A lute ( or ) is any plucked string instrument with a neck and a deep round back enclosing a hollow cavity, usually with a sound hole or opening in the body. It may be either fretted or unfretted.
More specifically, the term "lute" can ref ...
s commonly have elaborate
rosettes.
The sound board, depending on the instrument, is called a ''top plate'', ''table'', ''sound-table'', or ''belly''. It is usually made of a
softwood, often
spruce
A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
.
In a grand
piano
The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some early pianos used leather). It is played using a keyboa ...
, the sound board is part of the case. In an upright piano, the sound board is a large vertical plate at the back of the instrument. The
harp
The harp is a stringed musical instrument that has a number of individual strings running at an angle to its soundboard; the strings are plucked with the fingers. Harps can be made and played in various ways, standing or sitting, and in orche ...
has a sound board below the strings.
More generally, any hard surface can act as a sound board. An example is when someone strikes a
tuning fork
A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs ( tines) formed from a U-shaped bar of elastic metal (usually steel). It resonates at a specific constant pitch when set vibrating by striking it agains ...
and holds it against a table top to amplify its sound.
See also
*
Piano acoustics
Piano acoustics is the set of physical properties of the piano that affect its sound. It is an area of study within musical acoustics.
String length, mass and tension
The strings of a piano vary in thickness, and therefore in mass per length, w ...
References
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String instrument construction
Guitar parts and accessories
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