Robert Greenberg

Historian, Composer, Pianist, Speaker, Author

Dr. Bob Prescribes: Johann Sebastian Bach, Sonatas and Partitas for Solo Violin

We cannot (and will not!) talk about Sebastian Bach’s landmark Sonatas and Partitas for Solo Violin without first considering what is, to my mind, one of the most perfect examples of human ingenuity this side of cave painting, and that is the violin.

The Violin

The violin is a miracle of ingenuity and nature, of art and science.  Here are some particulars.  

Oldest extant violin, known as the “Charles IX,” built by Andre Amati in Cremona, Italy, circa 1564
Oldest extant violin, known as the “Charles IX,” built by Andre Amati in Cremona, Italy, circa 1564

The instrument we call the “violin” appeared around the year 1530 and continued to evolve until it reached its (more-or-less) definitive size and shape – in the late 1600s and early 1700s – in the hands the great violin gurus of Cremona, Italy: Nicolo Amati (1596-1684), Antonio Stradivari (1644-1737), and Giuseppe Bartolomeo Guarneri (1698-1744). 

Depending upon whom you talk to, the violin consists of up to 83 parts. (That’s because different ways of counting will yield up a different number of parts; for example, the back of a violin can be made up of one or two pieces of wood.)  

Whatever.  No matter how you count the individual pieces, the violin ultimately consists of three essential components: the resonating body (the sound box), typically 355 millimeters (or 14”) in length; the neck with the fingerboard; and four strings lying across and elevated by a bridge.

A modern violin bow is roughly 730-750 millimeters (or 29”) long.  The playing surface or “band” of bow hair is roughly 640-650 millimeters (or 26”) in length.  The upper end of the bow is called the “tip” (right, clever!); the lower end is called the “frog.”  A good bow can often cost almost as much as the violin itself.  

So what have we got?  Reductionism at its most extreme: a wooden box with four strings strapped over it, strings set in motion by dragging rosin-impregnated horsehair across them.  

But wait, there’s more!

The violin is, in fact, a miracle of technology, of form and function.  When the bow sets a string or strings in motion, the vibrations are transmitted to the top of the violin via the bridge.  

In an article entitled “Science and the Stradivarius” the violin maker and acoustician Colin Gough describes, in the simplest possible terms, the basic workings of the violin. (For our information, Gough received the 2001 Science Writing Award for Professionals in Acoustics from the Acoustical Society of America for this article.  The entire article can be found here.)

“Sound is produced by drawing a bow across one or more of the four stretched strings. The string tensions are adjusted by tuning pegs at one end of the string, so that their fundamental frequencies are about 200, 300, 440 and 660 Hz – which correspond to the notes G, D, A and E. However, the strings themselves produce almost 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 [the front and back] act rather like a loudspeaker cone, and it is the vibrations of these plates that produce most of the sound.

Cross-section of a violin, as viewed from below
Cross-section of a violin, as viewed from below

The strings are supported by the “bridge,” which defines the effective vibrating length of the string, and also acts as a mechanical transformer. The bridge converts the transverse forces of the strings into the vibrational modes of the sound box. And because the bridge has its own resonant modes, it plays a key role in the overall tone of the instrument.

The front plate of the violin is carved from a solid block of fine-grained pine. Maple is usually used for the back plate and pine for the sides. Two expertly carved and elegantly shaped “f-holes” are also cut into the front plate. 

The f-holes play a number of important acoustic roles. By breaking up the area of the front plate, they affect its vibrational 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 f-holes. The resonant frequency is determined by the area of the f-holes and the volume of the instrument. It is the only acoustic resonance of the instrument over which violin makers have almost complete control.

Early in the 16th century it was discovered that the output of stringed instruments could be increased by wedging a solid rod – the “sound post” – between the back and front plates, close to the feet of the bridge. 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 a larger amplitude. This increases the radiating volume of the violin and produces a much stronger sound.

The violin also has a “bass bar” glued underneath the top plate, which stops energy being dissipated into acoustically inefficient higher-order modes. The bass bar and sound post were both made bigger in the 19th century to strengthen the instrument and to increase the sound output.”

Got all that?

The role of the violin body – the sound box – is to transmit the string vibrations to the outer air, and a violin is a good violin to the degree that it transmits the string vibrations of the fundamental pitch and all of its 20 harmonics (or partials) with equal response over the entire range of the instrument.  The actual tone of a violin, then, depends initially on the cellular structure of the wood from which it is built (ideally old-growth spruce, pine, and maple from a cool, meaning slow growing environment), on the many so-called “resonance frequencies” of the wood, and on the resonance frequencies of the wood’s capacity to respond to the strings’ vibrations, to say nothing of the relative flexibility of the varnish, the makeup and quality of the strings (silk verses gut verses copper verses silver verses bronze verses aluminum verses steel), how a given player actually holds the violin, the humidity in the room in which it is being played, and so forth.  A violin is a complicated acoustical system, and the particular “sound” of a particular violin is dependent upon a tremendous number of variables.   

The violin is an instrument capable of a seemingly infinite degree of nuance, vocality, and expressivity; it is that single Western instrument closest in sound and suppleness to the female voice. Truly, if instrumental practice springs originally from the human voice, then the evolution of bowed string instruments was an ongoing attempt to create an instrument capable of achieving the same degree of nuance and lyricism as the human voice. …

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