Fredrik
Edelstam and Carl-Johan Eelde
Today there are many sports tracking applications, but
none of them give the runner feedback on running technique. The purpose of this
study is to do a mapping between input and output in a sports tracking
application that enables sonification. A scheme for sonification is also
presented, but not evaluated. The method corresponds to the design phase of an
iterative design study. The method also includes a survey to give additional
information for the choice of mapping. A good running technique depends on the
step length, relaxation, a straight posture, upright head, unclenched fists,
setting the front half of the foot down first upon ground impact, having ground
contact with the foot for long enough, the runner’s vertical oscillation, the distance
between the projection of runner’s centre of gravity to the ground and where
the foot is set down, the angle at the elbows, that the arms move in
counterphase with the legs, the tilt of the upper body and a slight tilt from
the ankle.
To measure running technique, GPS, accelerometers,
gyroscopes, barometers, pedometers and pulse measuring devices can be used. 37
persons answered the survey. Significantly fewer respondents wanted feedback on
their running technique. The mapping is between speed, combustion, distance and
vertical displacement to the accelerometer of the smartphone, route to the
smartphone’s GPS, upright head to a gyroscope, straight posture to the
gyroscope of the smartphone and a gyroscope at the neck, distance between foot
impact and projection of the runner’s centre of gravity to an accelerometer at
the foot in combination with the smartphone’s accelerometer and that the front
half of the foot is set down first to two barometers placed by the toes and the
heel.
The suggested scheme for sonification is to alter or
add to the music that the runner is listening to while running. Vertical
displacement is sonified by an added “twang”-sound, the distance between the
projection of runner’s centre of gravity to the ground and where the foot is
set down is sonified by altering the music with a highpass-filter with varying
cutoff-frequency, straight posture is sonified by a lowpass-filter with varying
cutoff-frequency, the tilt of the head is sonified by the sound of wind added
to the music, setting the front half of the foot down first upon ground impact
is sonified by heavy footstep sounds whenever the heel is set down first and
having ground contact with the foot for long enough is sonified by a warning
siren whenever the ground contact is too short.