If you understand the construction of a violin, you can understand how it works. There are two ways that you can play a violin: plucking and bowing. When you pluck, the string briefly vibrates and then stops. When you use a bow, a different effect is made. A bow is a long wooden shaft holding a strand of hoarse hair. When force rubs the hair against the string, the string catches on the follicles and is stretched. When the string cannot be stretched any further by the follicle, it breaks off and attaches to another, and if the hair is still moving, the cycle repeats (see animation). The friction between the string and the bow cause a violent vibration which travels down the bridge into the wood, which resonate. Out of all the work put into moving the bow and the other energy required, only 2% is transferred into sound, the rest goes to heat between the bow and string, and other forms (not very efficient!) (Schelleng, 1974). When the bow is pulled and the string vibrates, the vibration is carried through the bridge and into the body which puts out the sound.
        Why do the same strings make different sounds when you press your finger against them at different points? You must first understand frequencies and harmonics. When a string vibrates, it sends out a wave that, when it reaches a barrier, bounces back onto oncoming waves. In most cases, these collisions cause no useful work, but in rare cases, when the length of the string is similar to the wavelength and the vibrations match up, we hear them. When the frequency is equal to the wave's speed over twice the string length, it is said to be the fundamental frequency, or first harmonic. The frequency of the second harmonic is twice that value. From this we get

        fn=n(v/2L)

where f=freqency, v=wave's speed, L=string length, and n=harmonic # (1st,2nd,etc.). We can hear all harmonics up to a certain level. So when you play a string, many frequencies are made, but we only hear the harmonics (Duffy, 1997).
        Each string is tuned to their own fundamental frequency and has harmonics, but they sound different. This is because their mass to length ratios are different. When at the same tension, the higher the ratio is, the lower the note.
        The tone also changes depending on the position of the barrier (usually your finger) on the string. To get certain notes, the barrier must be at a certain position. Guitar makers, who put frets (metal bars) as barriers use the rule of eighteen, which states: each fret should be placed 1/18 the distance from the previous fret to the bridge. But since the ratio is not exact, only close, the notes become a little off. To find the exact placement of the barriers, we say:

        x=d/17.817

where x is the distance to the next barrier and d is the distance from the previous barrier to the bridge (see fig. 3) (Rossing, 1982).
        Now do you understand what we hear and how it's made?

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