In this thesis we seek to explore the potential for continuous key position to be
used as an expressive control in keyboard musical instruments, and how preexisting
skills can be adapted to leverage this additional control. Interaction between
performer and sound generation on a keyboard instrument is often restricted
to a number of discrete events on the keys themselves (notes onsets and
offsets), while complementary continuous control is provided via additional interfaces,
such as pedals, modulation wheels and knobs. The rich vocabulary of
gestures that skilled performers can achieve on the keyboard is therefore often
simplified to a single, discrete velocity measurement. A limited number of acoustical
and electromechanical keyboard instruments do, however, present affordances
of continuous key control, so that the role of the key is not limited to delivering
discrete events, but its instantaneous position is, to a certain extent, an element of
expressive control. Recent evolutions in sensing technologies allow to leverage continuous
key position as an expressive element in the sound generation of digital
keyboard musical instruments.
We start by exploring the expression available on the keys of the Hammond
organ, where nine contacts are closed at different points of the key throw for each
key onset and we find that the velocity and the percussiveness of the touch affect
the way the contacts close and bounce, producing audible differences in the onset
transient of each note.
We develop an embedded hardware and software environment for low-latency
sound generation controlled by continuous key position, which we use to create
two digital keyboard instruments. The first of these emulates the sound of a Hammond
and can be controlled with continuous key position, so that it allows for
arbitrary mapping between the key position and the nine virtual contacts of the
digital sound generator. A study with 10 musicians shows that, when exploring
the instrument on their own, the players can appreciate the differences between
different settings and tend to develop a personal preference for one of them. In the
second instrument, continuous key position is the fundamental means of expression:
percussiveness, key position and multi-key gestures control the parameters
of a physical model of a flute. In a study with 6 professional musicians playing
this instrument we gather insights on the adaptation process, the limitations of the
interface and the transferability of traditional keyboard playing techniques
