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1178Re: Alpha/Theta feedback

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  • yaniv_vi@yahoo.com
    Sep 2, 2001
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      hi
      is sound great , working with open eeg .
      how do you feel ? how's alpha feedback feels ?

      yaniv
      --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
      > 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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