Chapter 1.2

Damping

A note is a vibration. The next note is another vibration. The bow vibrates each time the string is set in motion. If the bow stops moving, the note sounds a bit longer and dies away. A plucked string vibrates much longer. But the player uses the bow to make the instrument play the next tone. It is therefore desirable that the bow addresses the next note as it ought to, rather than continuing happily in the direction it was first asked to move.

The movement of the bow is a reciprocal relationship between the hair and the stick. The greater the tension on the hair, the more responsive the bow. The less the tension, the more the vibration is damped. The bow must therefore not only activate the string when moved, it must also stop it. The damping is actually inaudible, but can be felt as resistance. It is the feeling that the player can shape the note, that the bow does exactly what is asked of it, but no more.

The damping, however, affects not only the end of a note, but also the sound. The sound is in fact a specific combination of overtones. That some overtones are less strong or even entirely missing, is because they have been dampened away. One can imagine this in terms of a colour. If we see a red colour, this is red because the material absorbs the other colours of the spectrum. It is more or less the same with a note. We hear it as it is, because the other possible overtones become absorbed by the instrument and by the bow. Which overtones are absorbed depends on many things, but I will restrict myself to the function of the bow. Here the material is very important, particularly the nature of the wood, its thickness and mass, the length of fibres, the thickness relationships and the tension to which everything is subjected. There is hardly a detail of the bow which is not engaged in damping.

It is clear that the bow is a tool for producing a note, but the way it damps the tone is at least as important. That the bow too vibrates with every note can be felt by touching the stick. I will try to analyze these vibrations by concentrating on one hypothetical oscillation. This is something like concentrating on a single water molecule in the bathtub. It is very difficult. But it is absolutely certain that water molecules exist and that they move. Our vibration works the same way. It exists, and it moves. The bow rests on the string. There is no sound. When the player moves the bow, the vibration begins at the point where the bow rests on the string.

The vibration can go in two directions, forward toward the head, and backward toward the frog. I will follow the first, which moves toward the head. First, the hair vibrates. Of course, this too has a damping effect, as does every material in its respective way. But, under tension, the hair is extremely elastic. It transmits the vibration without disturbing it much. Now the vibration reaches the ivory at the tip, then the ebony, then the mass of pernambuco that constitutes the head of the bow. Even if our vibration has a powerful effect on the hair, it can hardly move the head. In addition, it has traversed a variety of materials, each with its own damping effect. It has therefore already taken something of a beating. What is left of it advances from the head to the thinnest part of the stick. There it can catch its breath, but the further it moves along, the thicker the stick becomes, which damps it again. In fact, there is not much vibration left. If we pursue the vibration the other way toward the frog, the effect is similar. The hair meets metal, ebony, metal again, and then has to leap across to the stick. But now it gets an extra weight around his neck, the silverwinding. The effect of which is rather like the damper on a tennis racket.

The two attenuated vibrations meet along the stick like two ripples in water. The ripple from the frog might be slightly stronger, since the stick is thicker at this end. Although I have no way to prove this scientifically, I assume that the combined wave moves in the direction of the head, because every wave moves in the direction where it meets least resistance. A fraction of the original vibration is transmitted back through the hair via the head. But this is so minimal as to be overwhelmed by the counter-vibration. Our vibration has been damped.

The idea that the bow's main job in relation to the instrument has more to do with damping the tone than producing it is something that came to me only recently. But a willingness to see things this way is a key to understanding many of a bow's details. It is possible that many makers, who have made made fantastic bows, never thought about damping. But this hardly means that the theory is wrong.

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