Modal active control: A tool to finely adjust the sound of string instruments
Simon Benacchio · The Journal of the Acoustical Society of America · 2017
Controlling the vibratory properties of musical instruments is an important challenge for musical acousticians, musicians, and instrument makers. The latter try to control these properties modifying mechanical parameters of instruments like their shape or their materials to obtain some expected sound attributes. Musicians also modify the vibratory properties of their instruments to change their sound using mutes, for example. Musical acousticians try to modify these properties because it is an intuitive way to investigate the relationship between the instrument mechanisms and their sound attributes. Inspired by industrial techniques, active control was revealed as a convenient way to answer to the latter goal. Moreover, modal active control is a preferred method for the application to musical instruments since their modal parameters are believed to be good descriptors of their vibratory properties. This study aims at applying modal active control on string instruments. First, the possibilities offered by this technique are presented and experimented on several instruments. Then, examples of the control of specific phenomena are given. Couplings between the soundboard and strings for both a cello and a guitar are controlled to cancel the well-known wolf-note phenomenon for the former and to switch from strong to weak coupling for the latter.