5.1 Playability and minimum bow force

 

When a player says that one instrument is ‘easier to play’ than another, they presumably mean ‘easier to achieve the particular musical effect I want’. This suggests an interplay of the response of the string to the bow, the acoustical behaviour of the particular violin body, and the perception of the resulting sound: it combines all the threads of this article.

 

The analysis by Raman and Schelleng suggests that the maximum bow force to sustain Helmholtz motion should not be influenced by body behaviour in any obvious way, but that the minimum bow force is directly determined by body response (and other sources of energy loss).

 

Fortunately, there is a straightforward way to extend Schelleng’s analysis and incorporate a measured bridge admittance into the calculation of the minimum bow force, leading to a quantitative prediction for each played note on a given instrument.  An example is shown in figure 26. The frequency scale indicates the fundamental frequency of the played note, starting from G3 (196 Hz), the lowest note of the violin. High peaks indicate notes likely to be wolfy.

 

One aspect of playability that is often commented on is ‘range of tone’. As already seen in section 2.1, if a steady Helmholtz motion is produced by the player the most obvious way they can influence the tone quality is by changing the bow force, to make the Helmholtz corner more or less sharp and hence to vary the high-frequency content in the sound: this has been made explicit in measurements by Schoonderwaldt.

There are many other possible aspects of perceived differences of ‘range of tone’. Most of them concern transients, discussed in the next subsection, but there is one that should be mentioned first. More than one technically minded violin maker has suggested that violin body vibration can exhibit nonlinear behaviour of some kind.