BINAURAL BEAT BIOFEEDBACK FROM EEG
			by Philip Soden

DISCLAIMER
In using these files you agree that the author is not responsible for 
any injury to persons or property arising from such use.  The files 
may be distributed freely on condition that this readme.txt file is 
included in the distribution.  The files may not be sold or otherwise 
used for profit-making purposes without the written consent of the 
author.


HAZARD WARNING
Listening to binaural beat tones can produce altered states of 
consciousness and is reported to have triggered epileptic seizures. 
This application should not be used when driving or operating 
machinery, and should not be used by epileptics or by anyone 
receiving psychiatric treatment.


CONTENTS
This zip file (binaural.zip) contains the following:

BINAURAL.CFG	
A Waverider configuration file to generate a MIDI output from one 
channel of EEG, the output note varying with the average EEG 
frequency.

SYNTHUSR.SBK
A SoundBlaster AWE32 MIDI instrument based on 2 sampled sine waves 
(120Hz and 134Hz at c4 on the MIDI keyboard) panned left and right 
respectively within one instrument.  

BINAURAL.XLS
An Excel spreadsheet for calculating output frequencies of 
left and right channels, delta f (binaural beat) for a range of MIDI 
notes, and the effect of note range selection (in Waverider) on the
offset between measured EEG and fed-back binaural beat frequencies.

README.TXT
This text file.


HARDWARE / SOFTWARE REQUIREMENTS

To create binaural beat biofeedback from EEG, this setup needs a 
Waverider or Waverider Jr. and Waveware software to amplify and process the
EEG signals, a SoundBlaster AWE32 or compatible card that accepts *.sbk
files, plus a PC / compatible, with Microsoft Windows.

If you don't have a Waverider, you can skip the bio-feedback and still 
make binaural beat tones by using a MIDI sequencer / composition 
software to play a selected sequence of notes, using the synthusr.sbk 
file loaded into the Soundblaster AWE32.


SETUP

(Instructions are for SoundBlaster AWE32 - your mileage may vary)

Unzip the file and copy the binaural.cfg file to the c:\waveware\ 
directory.
  
Copy the synthusr.sbk file to the relevant Soundblaster subdirectory 
(e.g. c:\sb16\sfbank\)

Open AWE Setup and select User Custom Synth in the Synth Bank 
drop-down box, then select synthusr.sbk into user bank 1. As 
confirmation that all is well, the title "Binaural Beat Bank" should be 
displayed under the User Bank number selector.  Hit [Set] and quit 
AWE setup.

Start Waverider and select Load Configuration from the Files pull-
down menu. Select binaural.cfg, gel up the headband and you're ready 
to go.


HOW IT WORKS

The Waverider amplifies and processes EEG signals from electrodes on 
the Waverider headband, and the Waveware software produces a MIDI output
which controls the sound card from the EEG inputs. With the binaural.cfg
file loaded into Waverider, the output MIDI notes vary in pitch in
proportion to the average brainwave frequency.
 
The synthusr.sbk file configures the SoundBlaster AWE32 as a custom MIDI 
instrument to be played by the Waverider.  When a "note-on" signal is 
received from the Waverider, the SoundBlaster produces two sine waves of 
slightly different frequencies, one in each ear (headphones are 
recommended for effective binaural beat listening).

Playing a lower MIDI note makes both sine waves lower in pitch, as well 
as reducing the frequency difference (beat) between the two tones.  If a 
higher note is played, the frequency of the tones and also the beat
frequency between them are increased.

This gives useful conscious audible feedback in that the tones 
themselves follow the average EEG frequency up and down.  More to 
the point, the beat frequency between the two tones also reduces and 
increases, tracking the average EEG frequency.  

The theory of binaural beat stimulation is that brainwaves tend to 
follow the applied beat frequency (if the offset between EEG and
beat frequency is less than 15%), so by choosing a binaural beat
frequency that stays slightly below the average EEG frequency, it 
is possible to lead the EEG slower into alpha and theta states via this 
bio-feedback mechanism.

This combination of conscious and subconscious feedback is a powerful
way of centering and clearing the mind.  Rising tones give early warning
signals of potentially distracting thoughts even before the user is
consciously aware of the thought.

At the lower end of the range, the output frequencies become less and 
less audible due to the frequency response of the ear and of the 
headphones.  This helps to reach deeper meditative states where the 
tones would be distracting if continued at mid-range levels.


ADJUSTING PITCH AND OFFSET

The offset frequency (i.e. the difference between the average EEG 
frequency and the binaural beat frequency) can be adjusted, and can  
be set to lead the brainwaves up or down in frequency.  There are 
several ways of adjusting the offset, including the coarse and fine 
tuning within the .sbk, or selecting a different root note for the 
samples (you will need Vienna Studio or similar software to do either 
of these).  Another, perhaps easier method is to adjust the output note
range for the MIDI instrument within Waverider.  

Open binaural.xls (Microsoft Excel spreadsheet) to find the note range
combination that produces your desired offset.  The offset is initially
set at 0.4 Hz, leading downwards (i.e. the beat frequency is lower than the average 
EEG frequency).  

If you want to change the offset, enter another combination of start and 
end notes in binaural.xls until you reach the desired offset, and enter
those values in Waverider (double click on the Waverider MIDI display
window to access this function).  

Please note that negative offset values represent beat frequencies 
that are higher than the average EEG frequency, i.e. they would tend
to lead the brainwaves upwards into beta.  



TROUBLESHOOTING

If this doesn't work with your sound card, check against the manualŠs 
instructions for loading a user sound bank, and ensure that the card
can handle multi-layer samples within one instrument.
 

MORE...

Please send constructive criticism or suggestions to Phil Soden at
dven@mail.hkapa.edu

(c) Philip Soden 
     August 1995