  In the process of developing a new digital music interface, the author faced
three questions that have attracted little to no attention in the literature.
By tracking body joints, a performer can use body parts to directly control a
digital music instrument. An immediate question that follows asks which limb(s)
is more effective for the instrument. The next question asks that movement
should be measured relative to a particular reference point. And the last
question asks about the mathematical form of the mapping function from the
movement feature to the sound parameters. This paper attempts to discuss why
finding an answer to these questions is worthwhile and to provide possible
solutions that require further investigation.
