Effect of the Width of the Bow Hair on the Violin String Spectrum

Violinists often claim that tilting the bow provides greater brilliance. By tilting, the effective width of the bow hair is reduced and the bow force distribution across the bow hair ribbon is changed. Considering that the width of the bow hair of a violin bow is roughly 1/32 of the string length (about 10 mm), and that the relative bow-bridge distance in playing typically varies between 1/8 and 1/32, an effect of the width of the hair on the slip-stick process seems reasonable. Pitteroff [1] has reported simulations and measurements showing that the slipping intervals become progressively shorter as the width of the bow hair ribbon is decreased. However, the effect, which mainly was attributed to a faster transition from stick to slip at release, was small. In this study, evidence gained in experiments using a bowing machine is presented, showing that a decrease of the width of the bow hair may boost the string spectrum considerably for higher harmonics. A gain in partial amplitudes of 3 – 6 dB has been observed above partial 20. Besides increased brilliance, it is clear that there are several other reasons for violinists to tilt the bow. For example, tilting the bow hair facilitates gentle note attacks due to a gradual buildup in string contact.