Violin acoustics

The energy of a vibrating string is transmitted through the bridge to the body of the violin, which allows the sound to radiate into the surrounding air.

The number of harmonics present in the tone can be reduced, for instance by the using the left hand to shorten the string length.

The viola and the double bass’s characteristics contribute to them being used less in the orchestra as solo instruments, in contrast to the cello (violoncello), which is not adversely affected by having the optimum dimensions to correspond with the pitch of its open strings.

[3][4] The earliest violin makers, though highly skilled, did not advance any scientific knowledge of the acoustics of stringed instruments.

[5] During the nineteenth century, the multi-harmonic sound from a bowed string was first studied in detail by the French physicist Félix Savart.

[25] The vibrato effect on a violin is achieved when muscles in the arm, hand and wrist act to cause the pitch of a note to oscillate.

[25] The bridge, which is placed on the top of the body of the violin where the soundboard is highest,[34] supports one end of the strings' playing length.

[39] Muting is achieved by fitting a clip onto the bridge, which absorbs a proportion of the energy transmitted to the body of the instrument.

[42] The bow consists of a flat ribbon of parallel horse hairs stretched between the ends of a stick, which is generally made of Pernambuco wood, used because of its particular elastic properties.

[44] In 2004, Jim Woodhouse and Paul Galluzzo of Cambridge University described the motion of a bowed string as being "the only stick-slip oscillation which is reasonably well understood".

sulla tastiera) produces what the 20th century American composer and author Walter Piston described as a "very soft, floating quality", caused by the string being forced to vibrate with a greater amplitude.

[50] Sul ponticello—when the bow is played close to the bridge—is the opposite technique, and produces what Piston described as a "glassy and metallic" sound, due to normally unheard harmonics becoming able to affect the timbre.

Here, the nature of the friction between bow and string changes, and slipping or sticking occurs, depending on the direction the corner is moving.

[25] The Indian physicist C. V. Raman was the first to obtain an accurate model for describing the mechanics of the bowed string, publishing his research in 1918.

The theory was further developed during the 1970s and 1980s to produce a digital waveguide model, based on the complex relationship behaviour of the bow's velocity and the frictional forces that were present.

[36] It is made of two arched wooden plates known as the belly and the backplate, whose sides are formed by thin curved ribs.

[59] Their construction, and especially the arching of the belly and the backplate, has a profound effect on the overall sound quality of the instrument,[60] and its many different resonant frequencies are caused by the nature of the wooden structure.

[36] The wooden structure is filled, glued and varnished using materials which all contribute to a violin's characteristic sound.

The many modes that exist can be found using fine dust or sand, sprinkled on the surface of a violin-shaped plate.

[16] Modern research has used sophisticated techniques such as holographic interferometry, which enables analysis of the motion of the violin surface to be measured, a method first developed by scientists in the 1960s, and the finite element method, where discrete parts of the violin are studied with the aim of constructing an accurate simulation.

The effects of changing the new violin in the smallest way can be identified, with the aim of replicating the tonal response of the older model.

The bass bar is glued to the underside of the top, whilst the sound post is held in place by friction.

[66] When the bridge receives energy from the strings, it rocks, with the sound post acting as a pivot and the bass bar moving with the plate as the result of leverage.

[36] Together they make the shape of the violin body asymmetrical, which allows different vibrations to occur, which causing the timbre to become more complex.

[13] A sharp resonance response from the body of a cello (and occasionally a viola or a violin) produces a wolf tone, an unsatisfactory sound that repeatedly appears and disappears.

The C string has been described by Piston as having a timbre that is "powerful and distinctive",[71] but perhaps in part because the sound it produces is easily covered, the viola is not so frequently used in the orchestra as a solo instrument.

[72] According to the American physicist John Rigden, the lower notes of the viola (along with the cello and the double bass) suffer from strength and quality.

To correct this problem, Rigden calculated that a viola would need strings that were half as long again as on a violin, which would making the instrument inconvenient to play.

The proportionally greater thickness of its body means that its timbre is not adversely affected by having dimensions that do not correspond to its pitch of its open strings, as is the case with the viola.

[75] According to John Rigden, a double bass would need to be twice as large as its present size for its bowed notes to sound powerful enough to be heard over an orchestra.