Case example 2: The violin and the clarinet.

The authors give as an example a bowed string instrument, where control of pitch by finger position and control of timbre by bow position are examples of absolute dynamical functions; relative control of pitch by vibrato and of timbre by bow velocity and pressure are examples of relative dynamical functions; Selection of different tunings, whereas the act of putting a mute or changing an organ register are examples of static functions.

If we consider a clarinet:

• Absolute dynamical functions, performed by
• absolute amplitude: breath pressure (dependent on the particular embouchure).
• absolute pitch: fingering (also dependent on the particular embouchure).
• absolute timbre: the result of breath pressure for a particular embouchure ("virtual flow") [3]. The range is dependent on the embouchure value.
• Relative dynamical functions
• relative amplitude: breath pressure, embouchure.
• relative pitch: embouchure value and to a very small extent fingering (partial opening of holes).
• relative timbre: same as above (breath pressure and embouchure).
• Static functions: the change in the tube's length.

Basic relation between gestures and musical functions in the case of a clarinet:

A relation between Cadoz's gestures classification and Vertegaal et al. musical functions, can be done (in a rough way) if one considers that:

• Absolute dynamical functions can be accomplished mainly by exciter gestures or selection gestures, and in a finer degree also by parametric modulation gestures (e.g. lip pressure).
• Relative dynamical functions can be performed mainly by parametric modulation gestures and also by exciter gestures (e.g. the bow pressure controlling the violin's timbre). 8
• Static functions by structural modulation gestures.

From these considerations, one can stress the role of different feedback provided by each transducer type by referring to figure 1.2 and consider its application as performing a specific musical function or capturing a specific gesture. 9

Let's now complete the discussion about the gestural interface by examining briefly the different feedback types cited when we discussed the composed instrument model.

Wed Feb 10 10:07:20 MET 1999