PHY (MU) SICS OF VIOLIN
BY
PROF. T.T.SRINIVASAN

"Music is a divine art, the sweetness of which is a source of joy and attraction to all beings" ---gods, men and beasts
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Why is music called the divine art, when all other arts are not so called? We may certainly see GOD in all forms of arts and science, but in music alone we see Him free from all forms and thoughts. In every other art there is idolatry. Every thought, every word has its form. Sound alone is free from form and does not make any object appear before us. Music is said to be the speech of Angels. The meaning of a song goes deep and paints a picture in our mind. No one can express the effect of music on any person? Music is a kind of inarticulate, unfathomable speech, which leads us to the edge of the infinite. It occupies an important place both in religious and secular life. The realm of music is so all pervasive even scientists like Albert Einstein, Sir C.V.Raman, Dr. Raja Ramanna and others, many professional doctors, engineers, rich and poor people, and almost every living species are all associated with it in one way or the other. It is interesting to note that Physics and Music are close to each other.

If we put our finger gently on a loudspeaker we feel its vibration. If it is playing a low note loudly we can see it moving. When it moves forwards, it compresses the air next to it, which raises its pressure. Some of this air flows outwards, compressing the next layer of air. The disturbance in the air spreads out as a traveling sound wave. Ultimately this sound wave causes a very tiny vibration in our eardrum. Sound reaches the ear as repeating waves of compressed and decompressed air. These sound waves are clearly created by something vibrating. It can be the vocal cords, the prongs of a tuning fork, the body of a violin etc.

The violin is highly developed and sophisticated of all stringed instruments. It emerged in Northern Italy around the year 1550, in a form that has remained even today essentially unchanged. The famous Cremonese violin-making families of Amati, Stradivari and Guarneri formed a continuous line of succession that flourished from about 1600 to 1750, with skills being handed down from father to son and from master to apprentice. Violins by the great Italian makers are beautiful works of art in their own way, and are coveted by collectors as well as players. Every violin has a distinctive sound of its own. Just as any musician or a connoisseur can immediately recognize the difference between two singers, so a skilled violinist can distinguish between different qualities in the sound produced by individual Stradivari or Guarneri violins. It is a challenge for scientists to characterize such differences by physical measurements. Indeed, over the last century and a half, many famous physicists Helmholtz, Savart and C.V.Raman have been intrigued by the workings of the violin, and making vital contributions. Sir C.V.Raman has contributed number of papers both in string and percussive instruments and in addition he used to listen to violin virtuoso T.S.Tatachar's carnatic music on violin regularly in his house for many years.

All Cremonese instruments underwent extensive restoration and improvement in the 19th century. Prominent among the 19th-century violin restorers was the French maker Vuillaume, which is a copy of a Guarnerius violin. Vuillaume worked closely with Felix Savart, best known physicist of the Biot-Savart law in electromagnetism, to enhance the tone of instruments. Vuillaume, Savart and others wanted to produce more powerful and brilliant sounding instruments that could stand out in the larger orchestras and concert halls. Improvements in instrument design were also introduced to support the technical demands of great violin virtuoso like Paganini. Stradivarius violins are among the most sought-after musical instruments in the world. But is there any secret that makes a Stradivarius sound so good, and can any modern violins match the wonderful tonal quality of this great Italian instrument?

Sizes of Violin

Children learning the violin often use quarter, third, half, or three-quarter sizes. In all they are identical to full-sized instruments.The violin family includes the viola and cello, and in various sizes and tuning.

Physics of Violin

It has been known for a long time that the thickness of the wood and its physical qualities govern the sound of a violin. The sound and tone of the violin is determined by how the belly and back plates of the violin behave acoustically.

The parts of the violin

The violin is made of hollow wooden box, with a neck protruding from the top, and a internal sound post connecting the front belly and the back. The sides of the violin are called ribs. The belly is reinforced by an internal bass bar, which runs vertically through the instrument underneath the lowest G string. The raised outline on the outside of the violin surface is called a perflin.
The four strings run from a tailpiece attached to the base of the violin, across an wooden bridge, then upward just above the fingerboard. At the top end of the fingerboard, the strings cross the nut, a very small second bridge, mounted just slightly above the fingerboard. They then enter the pegbox, where they are wound around their tuning pegs, which are mounted sideways through tightly fitting holes in the pegbox. The tip of the pegbox is ornamented with a carved wooden scroll.The bridge of a violin has two purposes. First, it holds the strings in an arched configuration, permitting each to be touched separately by the bow.
The body. The body serves to transmit the vibration of the bridge into vibration of the air around it. For this it needs a relatively large surface area so that it can push a reasonable amount of air backwards and forwards. The belly and back plates are made so that they can easily vibrate up and down. The air inside the body is also important, especially for the low range on the instrument. It can vibrate a little like the air in a bottle when you blow across the top.
The bridge. The violin body is stimulated to vibrate by the bridge, which is wedged under the vibrating strings. The bridge effectively transfers some of the energy of vibration of the string to the body of the violin or sound box. This is one of the reasons for the bright timbre of the violin. The bridge has its own resonant modes; which plays a key role in the overall tone of the instrument. The strings which are supported by the bridge define the effective vibrating length of the string, and also act as a mechanical transformer. The effectiveness of the bridge can be reduced by attaching a mass to it called a mute, making the instrument both quieter and less bright in timbre.
The sound post under the right foot of the bridge connects the belly to the back plate. This stops the belly from collapsing under the vertical component of the tension in the strings, and it also couples the vibrations of the plates. Early in the 16th century it was discovered that the output of stringed instruments could be increased by wedging a solid rod called the sound post between the back and front plates, close to the feet of the bridge.
The bass bar is under the other foot of the bridge. It extends beyond the S -holes and thus transmits the motion of the bridge over a large area of the belly. The bass bar and sound post were both made bigger in the 19th century to strengthen the instrument and to increase the sound output.
Generally the body, the sound post, and the bass bar are made of spruce a light but strong softwood. The back, ribs, neck, pegbox, scroll, and bridge are of maple a hardwood The fingerboard of a violin is made of ebony. Some old violins have ivory fingerboards
Two expertly carved and elegantly shaped "S-holes" appear in the front plate. The carving of the S-holes often helps to identify the make of the instrument. The S-holes play a number of important acoustic roles. By breaking up the area of the front plate, they affect its vibration modes at the highest frequencies. More importantly, they boost the sound output at low frequencies. This occurs through the "Helmholtz air resonance", in which air bounces backwards and forwards through the S-holes. The resonant frequency is determined by the area of the S-holes and the volume of the instrument. It is the only acoustic resonance of the instrument over which violin makers have almost complete control.

The Strings were originally made of guts. Such strings are rarely used in performances. However, they have a tendency to go out of tune and snap more easily than modern metal strings. A ( Sa ), D (Base Pa ) and G (Base Sa) strings are usually metal-cored and wound with metal for greater mass in order to vibrate at a lower pitch, with the E ( Pa) string being a metal mono-filament of steel. Synthetic cored strings wound with metal are also employed today; they combine some of the benefits of gut strings with greater longevity and tuning stability.The strings are supported by the "bridge", which defines the effective vibrating length of the string, and also acts as a mechanical transformer. However, the strings themselves produce no sound. To produce sound; energy from the vibrating string is transferred to the main body of the instrument, the so-called sound box. The main plates of the violin act rather like a loudspeaker cone, and it is the vibrations of these plates that produce most of the sound.

The pitch of a vibrating string depends on
» Thickness of the strings increases in the order from E, A, D &G. The length of the string doesn't change, and its tension does not alter much.
» The frequency can also be changed by changing the tension in the string using the tuning pegs: tighter gives higher pitch. This is what the player does during tuning.
» The frequency depends on the length of the string that is free to vibrate. The player changes the length by holding the string firmly against the fingerboard with his fingers of the left hand. Shortening the string gives higher pitch.
» Finally there is the mode of vibration. When we play harmonics, we induce the string to produce waves which are a fraction of the length of those normally produced by a string of that length.
Playing the violin Bows:

The violin is played by using the right hand to draw the bow perpendicular to the strings, near the bridge, causing it to vibrate.The most useful features of the violin result from their use of bows. The part of the bow that touches the strings is made of horsehair or a synthetic substitute. The wooden support for it is bent towards the hair and not away from it like an archery bow. The advantage of this is that when the player presses hard on the strings, the wood straightens and pulls the hair tighter. This gives the modern bow a greater range of loudness. The strings are moved by the bow. When we fake it towards, the arm moves the bow, which moves the strings, the bridge, the violin body, the air near it to the ear drum that makes nerve signals of the brain to instruct the parental yap to go on about. Thus sound production on the violin starts with the bow's slip-and-grab act on the string. The bow's friction moves the string to the side. Eventually the friction is overcome, and the string slips. The bow grabs again, and slips again, repeating the cycle. The slip-and-grab routine divides the string into two straight-line sections with a kink, or bend, between them. This kink moves along the string as many times as the note's frequency or oscillations per second, for the note produced. Sound waves are generally depicted as curves; the string actually transmits a saw-tooth wave to the bridge. Between the large peaks are smaller peaks that carry a subtler form of sonic information that helps set the timbre, distinctive tone of the instrument and musician? These smaller peaks reflect factors like bowing pressure and speed. Until the bridge stimulates the violin body there is little sound. When the string and bridge vibrate precious little air directly in the body, it�s at this point; we encounter the astoundingly complex acoustic shape of the violin body which gets really complicated. This may sound straightforward, but the sexy curves of a violin body create an uncountable number of resonances, and they give the fiddle (When played as a folk instrument, the violin is referred as a fiddle) in its master's hands an unmatchable tone. As you know, solid objects can resonate or vibrate freely at certain frequencies. The force exerted by the bowed strings causes the bridge to rock about this position, causing the other side of the plate to vibrate with larger amplitude. This increases the radiating volume of the violin and produces a much stronger sound. The resonant frequency of a violin string, for example, is determined by its mass, length and tension. Similarly, the resonant frequency of a violin body reflects its size, shape and mass. The violin has an enormous number of resonances, as you change frequency; you pass over these resonances at random. The sound quality in a single note is changing all the time, and the ear is probably the world's most sophisticated spectrum analyzer.

To understand tone, we need one more factor called Vibrato produced by a gentle sideways flexing of the left hand. Vibrato changes the string's length, and hence its pitch. Vibrato which is a repeated fluctuation of pitch is an important part of most music. Note the visible and audible differences between vibrato and straight tones. Musicians can vary the speed and/or the width of the vibrato. Width is the rate of pitch fluctuation.

"There's nothing more boring than a sound that does not vary."
Fingering and positions

The placement of the fingers on the strings invokes no physical aid like frets as in veena or sitar. The player must achieve the correct position from practice alone, or else the instrument will sound out of tune.The reason for Violin players practicing for long hours is partly to train their fingers to land in the right places, and partly to cultivate the ability to correct the pitch very rapidly as it is played.

The violin is so complicated, there's no way science can predict and control every resonance: "It's fairly safe to say that basically science has illuminated how they work without improving them."
Some of the following questions remain unanswered by the physicists even today.
1. To get the excellent tonal quality of violin
» The position of the bridge, its material and the make is important,
» The position of sound post and quality of wood used to make it,
» The quality of strings is important.
These vary from one instrument to another. No fixed rule for this.
2. The same violin gives different tonal quality in the hands of different artists.

--------- Prof. T.T.Srinivasan .

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