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The method for signal processing was repeated for the second performer whose
alpha controlled a third and fourth oscillator via a second envelope generator for
their ampli
cation and that of a secondary tape machine (but no subsequent
filter in
this path).
With two performers generating biological signals, Teitelbaum performed the
role of conductor. He manually played the system controls (synthesis, reverb and
mixing parameters) in response to the performer
s alpha alongside injecting his own
musical intuition. Alongside, its use of brainwave information as a control input to
an electronic musical system
In Tune
introduces the use of brainwaves as a col-
laborative musical tool for performers and raises interesting questions regarding the
potential in
'
uences of biofeedback between individuals in shared musical envi-
ronments not just of brainwaves but from other bio-signals.
The
fields of biofeedback and aesthetic experience became increasingly popular
in the late 1960s and early 1970s. During his time at the Laboratory of Experi-
mental Aesthetics, part of the Aesthetic Research Center of Canada, David
Rosenboom conducted a thorough body of research into biofeedback and the arts,
de
nitively recorded in his 1990 writing
Extended Musical Interface with the
Human Nervous System
(Rosenboom
1990
).
Other artists at this time were also experimenting with alpha, such as Finnish
artist Erkki Kurenniemi
s instrument
Dimi
-
T
, where EEG was used to control the
pitch of an oscillator (Ojanen et al.
2007
). Manfred Eaton
'
s ideas for an adaptive
biofeedback instrument presented in his book
Bio
-
Music
(Eaton
1971
) presented his
concept of a musical brain system powered by visual and auditory stimuli. What is
signi
'
cant in his idea is that the images or sounds that are presented as stimulus for
generating brainwave activity can be semantically removed from the music as long
as the corresponding brain activity is one desired by the composer. This concept is
now a common tool in contemporary BCMI design, where stimuli are used to
generate speci
c brainwave information or
meaning
, but is unrelated to the musical
outcomes; this will be discussed in more detail further on.
The study of alpha rhythms in music offered a rich time of creative practice.
Ultimately, musical and artistic works were restricted by the limits of control that
came with generating and analysing alpha. In order to use the brain for more
advanced musical applications, new methods of harnessing and interpreting brain
information were required. Yet the work undertaken in using alpha waves to control
music was an important landmark in the
field of BCMI, as it suggests that the
notion of music controlled by thought was actually achievable.
In 1995, Roslaie Pratt and colleagues at the Biofeedback Research Laboratory in
Brigham Young University reported on experiments where children with ADD and
ADHD used neurofeedback training with the aid of music containing discernible
rhythms, to increase focused behaviour through the reduction of theta activity (Pratt
et al.
1995
). These experiments provided bene
ts that were still discernible
6 months later. Years later, sound and music were the focus in Hinterberger and
Baier
s body of work in providing aural elements to an slow cortical potential
(SCP)-driven communicative tools, such as rewarding musical jingles linked to
successful EEG control, and in their system POSER, short for Parametric Orchestral
'
