Information Technology Reference
In-Depth Information
As technologies for monitoring brainwave information have advanced so too has
the
field of computational music. This correlated evolution of technologies and
understanding of EEG has shaped the direction of brainwave-controlled music.
Both
fields have produced knock-on effects in this area, from the introduction of
MIDI that led to new applications of brainwaves with music to the advancement of
BCI, allowing BCMI research to shift
towards its engagement with cognitive
control of EEG.
In order to elicit control over EEG, it is essential to be able to decipher meaning
within EEG data that directly correlate with the subjective decisions (control
choices) of a user, be it a mental state or a cognitive task. This quest for accurate
meaning in EEG information has long been at the forefront of BCMI research, as
through precision in generating data comes accurate control. Note that the term
meaning here refers to understanding the correlation between a user
s mental
process and an associated brainwave response. Meaning in this manner does not
refer embedded or implied thought patterns within brainwaves (unless otherwise
stated later on). Mappings are not necessarily dependant on control, as generative
mappings that interpret unknown EEG information can produce interesting music,
but the two can feed off of each other in terms of complexity. When control is
explicit, the ability to introduce complex mapping strategies for more advanced
musical control arises.
In this chapter, we use the term
secondary
mappings to refer to a mapping as an
aside of an input
'
s primary connection. A secondary mapping may not necessarily
be directly presented to a user, it may be used for time-based data harvesting for
algorithmic rule-based mapping, or it may just not take precedence over a primary
mapping.
'
10.3 Mapping and Approaches to BCMI
The BCMI systems presented in this chapter differ in terms of application, cost,
equipment type and signal processing, data handling and indeed mappings, but all
can be said to consist of the following elements (Fig.
10.1
):
Stimuli This element is optional and in some cases where it is present provides
the feedback link with the system, being part of or being affected by the musical
system.
EEG Input Electrodes placed on the scalp, either in the form of a brain cap or a
headband to
t them.
Signal Processing Ampli
cation of electrical activity and data extraction to
isolate meaningful information. Filtering and further data processing/analysis/
classi
cation are applied depending on the EEG technique used.
Transformation Algorithm Transforming the EEG information into parameters
within a musical system. This is where mapping of non-musical information to
the music engine occurs. This can take various forms from a patch cable from an
