visualizing average alpha frequency

[valdesad1]

Is there a way to visualize to the user their average alpha amplitude across a specified frequency range; that is, perhaps using the power spectrum display box, is there a way to display the average amplitude of the 8-12 range (alpha) to the user, as opposed to displaying an individual bar for each frequency.

[lbonnet]

Hi valdesad1,

You may use a signal dislay box to visualize such "level".
- Filter your signal in the desired frequency range
- use a time based epoching to slice your signal into large epochs (for example 1 sec epoch every 0.5 sec)
- Average the epochs using Epoch Average
- display the result in a signal display.

To actually display the alpha level in an understandable way, you will have to change the time scale of the signal display.
This depends on the epoching parameters. For example, with 1s every 0.5s, you end up with 2s of signal every "real" second.
Thus you have to double the time scale in the signal display box.
I know this may sounds a bit strange, but the signal display is not really meant to be used on epoched signal.

Look at openvibe-scenarios/bci/neurofeedback.xml.
This scenario computes the band power of a defined frequency range. This is quite close to what you want.

Laurent-