From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2001-09-02 12:41:31
Hi,
since about 5 days I am using the comEEG prototype for
Alpha/Theta audio-feedback. Electrode positions for
1 channel are Cz - A2
(A2 should be right ear lobe. Is that right ? My picture with electrode-
positions is a little bit unclear).
Audio-feedback is given using two sine-wave oscillators (one lower
frequency for Theta and one higher frequency to indicate Alpha)
which amplitudes are controlled by the geometric addition
(root sum of squares) of the FFT output for each frequency band.
If a (fixed) threshold of 25uV is met, the feedback sound
is played at a low volume. A voltage between 25uV and 50uV increases
the volume and everything above 50uV is played at maximum volume.
With this setup I have been able to increase Alpha (lying position, eyes
closed), so that the Alpha-feedback sound is played nearly 100% of time.
However I have no idea how to get significant Theta.
What am I doing wrong ?
Should I train Alpha with higher thresholds first ?
And what is the great difference in
inner perception between Alpha and Theta ?
Regards,
Joerg
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