biofeedback

[Curtin, Steven D (Steven)]

Happy new year and thanks for the inquiry.  This is a great book!  I was
doing some stuff with biofeedback twenty years ago and hooking EEGs up to
analog synthesizers, heavily inspired by the same book, and later studied
electronic music with Rosenboom at Mills.  I also worked on the "BodySynth"
EMG based MIDI controller for its creator Chris Van Raalte about ten years
ago.  

As Rosenboom says in the book, trying to get reliable information from the
mind with an EEG is like sticking a jack hammer in the side of a computer to
find out the details of digital circuitry.   He's since been working with
something called "evoked potentials" for better EEG control of instruments.
Here's his web site:  http://music.calarts.edu/~david/index.html.  There has
been a recent CD release of his EEG music on pogus called "Invisible Gold"
(www.pogus.com).  He's fairly approachable and may be able to direct you to
other and more recent sources of information about the amplifiers you have
and what you want to do.

There have been various brainwave interfaces, such as IBVA, over the years.
One challenge is getting quiet enough differential amplifiers, since the
signals coming off of the scalp are in the microvolts.  The other challenge
is making sense out of the signal.  A typical EEG consists of a number of
bandbass filters after the preamp, followed by an envelope follower.  There
is a good picture of this in the Rosenboom book.  FFTs are used these days,
IBVA had a nice color FFT waterfall display of incoming brainwave activity.
I saw something on the news recently about a breakthrough with a biofeedback
interface for a computer, where people could think something and this could
be converted into a given word.

Controlling a synth with biofeedback takes practice like any other
controller or instrument.  Meditation, Zen or otherwise, is good practice
for this.  Drugs are not a good idea.  Also make sure everything is both
battery powered and optically isolated from any synthesizer equipment you
want to control, since an incorrectly-wired AC socket can cause potentially
lethal currents to travel up a patch cord.  

Steve C

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Steven Curtin  
Agere Systems (formerly
Lucent Technologies Microelectronics)
ph: (732)949-4404   fax: (732)949-6711
http://curtin.emf.org
sdcurtin at agere.com
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> ----------
> From: 	Crystal[SMTP:gosd at mwaz.com]
> Sent: 	Monday, January 01, 2001 12:06 AM
> To: 	synth-diy at node12b53.a2000.nl
> Subject: 	biofeedback
> 
> hi folks,
> i'm interested  in building a brainwave interface for one of my homebuilt
> modulars. anyone out there with experience doing this. i have an amazing
> book called Biofeedback and the Arts edited by David Rosenboom that
> includes
> patches and some schematics (state of the art 1974). i also have some
> expoxy
> potted module isolation amps which i'd like to use. they are marked LX0402
> CRIbox, not sure the manufacturer. happy roman calender new year all....
>