Sissy - Elise van den Hoven

notes and passages 45% stated the interface was
reasonable and 55% indicated it enabled a little or none at
all. This question generated a high level of commentary.
These comments included the beat detracting from the
activity as the need to follow it hampered expression.
Two participants indicated the interface should use analog
force data to allow potential sound modulation and better
expression. The last response relevant to this paper was
based on the ascending arrangement of the note mapping.
82% of respondents indicated that the mapping allowed
for a reasonable playing of a musical passage and felt the
arrangement could be learnt. Criticisms included the
directions of keys were hard to follow and the frustration
with having to use the legs instead of fingers, given by a
regular piano player.
Reflection on the design outcome
In an attempt to understand the results we return to the
initial design aims of the project. These were to provide
sufficient physical information to support feet moving as
note play, and to extend the piano spatial mappings for
greater harmonic expression. Through these results it can
be concluded that the inherent or felt experience of the
interface was initially over designed. The dimpled rubber
cover was not needed, as the compression provided by the
foam between the timber layers was sufficient for the
feedback on the note play. The coupling to the sound
feedback was at a sufficient latency to encourage
continual interaction but it was not dynamic enough to
enable expression through the feet or bodily movement.
Whilst it was a compromise to use the selected microcontrollers;
we now know they were central to the
expressive failure of the interface, due to their signal
processing limits, even with our attempts to colour the
note in the sound software. As a design quality the
interface needs to allow for sound expression through
subtle bodily movements, we cannot be compromised by
technologies that do not deliver on this aim. Future work
is needed on the redesign of either the electronic sensing
method, the mechanical pad design, to allow for tilt for
example, or both. We will also consult literature on
methods and techniques to enable dynamic expression.
In terms of the spatial mapping the results indicate that
the Musical Staircase was largely successful. Comments
indicated it was learnable and not too different from a
piano or other chromatic mappings such as guitar fret
boards.
CONCLUSIONS
This design process has been through once cycle of
Framing the Problem, Design Response and User
Evaluation based on the brief determined by the COM.
Creating musically expressive public installations within
challenging site conditions and budgets have major
implications on the technologies that can be used and the
interaction that can be offered. We intend to take the
work further with a greater research focus on bodily
movement and technologies required to leverage these for
expressive interactive purposes.
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Reflection on the process
Examining the precedents to the Musical Stair indicated
gaps in their potential for a physically expressive
experience. This shortcoming we determined was due to
the lack of inherent or physical information on the act of
stepping and moving to create sounds. Add to this the
need for a spatial mapping that allowed for more than a
linear stepping pattern.
We used this knowledge to frame our design efforts in
realising the Musical Stair. The resultant prototype
enabled user evaluation with an appropriate participant
group. The questionnaire findings give an understanding
of the general attitudes towards the Musical Staircase as
enabling continuous interaction and expression. However
little is yet understood about the movement quality
afforded by the stair pads in terms of issues such as haptic
feel and spatial affordance. To attain a finer grained
understanding of these qualities will require further
analysis of the video footage with particular focus on
these qualities.
Returning to the idea of reflective practice for movement
and embodied interaction design we can see a very
different process is needed to influence good decision
making than would be used for conventional disciplines
such as Architecture and Industrial Design. In our view
designing for embodied and movement based interaction
requires,
• A robust model of the intended interaction,
• An examination of any precedents against this
model to develop a sophisticated framing of the
problem
• A design response through demonstration
prototype
• User evaluation of this prototype
As interaction design deals in the temporal and
experiential qualities of interfaces it requires user
evaluation to give rich descriptions of these experiences
through the usage of functioning prototypes. So to adapt
Schön’s (1983) notion of reflective practice to embodied
and movement based interaction the above steps need to
be taken, not particularly in this order, to inform the
design decisions and to reframe the subsequent iterations.
We invite scrutiny on this model.
REFERENCES
Schön, D. The Reflective Practitioner. London: Basic
Books, 1983.
Ullmer, B , and H Ishii. "Emerging Frameworks for
Tangible User Interfaces." IBM Systems Journal
39, no. 3&4 (2000), 915-31.
Wensveen, S, T Djajadiningrat , and C Overbeeke.
"Interaction Frogger: A Design Framework to
Couple Action and Function through Feedback
and Feedforward." Paper presented at the
Designing Interactive Systems, Cambridge, MA,
2004.