Filtering string
The filtering string is a special music instrument, using, as connector between gesture and sound, a physical model of a slowly-moving string. This caracteristic, added to the gesture control that enables to shrewdly interact with the string, give the filtering string a great expressiveness. This can be visualized through the display onscreen of the string ; the instrument is perceived as a living entity, sound and visual, that the musician comes to play with.
Instrument introduction
The “Filtering String” instrument uses the shape of a slowly-moving string to control the gains of a filter bank. This instrument is based on the idea that using a dynamic system to control a simple synthesis will produce sounds with a richer spectral evolution in time than in cases where the synthesis is directly controlled by the user. This instrument incorporates a program module created to provide a high level of control over a string model, and has usually been used in scanned synthesis applications. This module makes it possible to exert an overall control over the string parameters, since gestural data can be directly connected to it. The module’s output is a list of parameters that correspond to the shape of the string; this shape has been used to control a filter bank.
The instrument is equipped with a graphic tablet [Wacom] controlling the string parameters (stiffness, tension, damping) and a touch surface [Tactex] controlling the forces applied to the string, along with a special mapping that enables the musicians to give the string whatever shape they want with their fingers. The users have to press the touch surface to apply forces to the string.
In live performances, the string shape is displayed on a screen, and besides the artistic effects of this display, it helps the audience to understand how the instrument works. In addition, since the visual feedback is closely linked to the sound, the audience can see that the auditory and visual aspects of the instrument are part of the same process.
Technical caracteristics
Gesture controller : Tactex MTC Express touch surface and Wacom A6 graphic tablet.
Sound processes : Noise filtered by a filter bank which gains are driven by a physical model of a slowly-moving string (moving at low frequences).
Programming : C language and Max/MSP.
Filtering string apllications
The filtering string has been used to compose and to perform the electroacoustic musical pieces "Le Rêve du Funambule", "Etheraction".
