Information Technology Reference
In-Depth Information
Fig. 1.4
Photograph of a subject operating the system
The two challenges that we had to address in this design were to devolve the
creative process to the user and provide more options for control. Technically, a
solution for the former would depend on the solution for the latter. Hence, we
started by focusing on increasing the number of controls. To this end, we shifted
from using EEG rhythms to adopting an evoked potential approach based on the
SSVEP method that I mentioned earlier.
The new SSVEP-Music system was implemented in collaboration with Joel
Eaton, a postgraduate research student at ICCMR, and John Wilson and
Ramaswamy Palaniappan
1
of University of Essex (Miranda et al.
2011
). Thanks to
the SSVEP approach, we were able to implement four switches for control, as
opposed to only one in BCMI-Piano. Moreover, each switch acted as a potenti-
ometer for continuous control.
Figure
1.4
shows a photograph of a subject using the system. The monitor on the
left hand side in Fig.
1.4
shows four images. These images
flash at different fre-
quencies, reversing their colours. Each image is associated with a musical task.
Therefore, the system executes four different tasks, which the user can select by
staring at the respective
flashing image.
The SSVEP control signal can be used to generate the melody in a variety of
ways, which can be customised. We provided a number of con
gurations that can
be loaded into the system. For instance, suppose that the top image, shown on the
monitor of the left hand side of the picture in Fig.
1.4
, is associated with the task of
generating a melody from an ordered set of
five notes (Fig.
1.5
). Let us say that this
image
flashes at a rate of 15 Hz. When one stares at it, the system detects that the
1
Currently at University of Wolverhampton.
