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spectral centroid analysis


Mar 26 2009 | 7:04 pm

Hello

I am wondering whether someone could give me a tip how to do a [I]spectral centroid analysis[/I], which calculates the spectral "centre of gravity" of the
signal; that is, the midpoint of its energy distribution. It is a
measure of the average frequency weighted by amplitude. This is
usually averaged over time (Miranda, 2006)

thank you
Krisztian


ch
Mar 26 2009 | 7:57 pm

Hi,

you can get a look at [centroid~] :
http://crca.ucsd.edu/~tapel/software.html

and [brigthness~] :
http://web.media.mit.edu/~tristan/

Ch.

Mar 26 2009 | 8:24 pm

wonderful, thank you.
K

Mar 29 2009 | 3:36 pm

Hello again

I wonder whether someone could help me here. I used the suggested objects [centroid] and [brightness] on the EEG data.
EEG data is in 120 Sampling rate.

The centroid object gives me a spectrum central of 17.2 hz which sounds good [attached picture]… but the 17.2 hz does not change at all and is the same in both hemispheres. (Live recording.)
I reckon this value should change at least a bit if I change my mind Smile, but at least when I move my eyes!

Any help greatly appreciated!!!

Krisztian

ps.: I might find something in here:
http://www.mitpressjournals.org/doi/abs/10.1162/comj.2008.32.3.87

best

Mar 30 2009 | 8:09 am
tedor wrote on Sun, 29 March 2009 10:36

I wonder whether someone could help me here. I used the suggested objects [centroid] and [brightness] on the EEG data.
EEG data is in 120 Sampling rate.

Out of curiosity, wondering what hardware and communication you’re using to get and read in the EEG data? It’s an interest of mine and I’ve tinkered a bit, but haven’t found anything very satisfactory yet (in ease of use or concerning accuracy).

Mar 30 2009 | 9:35 am

Hello James

I am using IBVA (bluetooth, 2ch, 3 electrode + earclip = bipolar) device. The software which came with it looks reliable. Gives me the visual representation of the raw data and the spectrum as well in 3d.

http://www.youtube.com/watch?v=MPOGguC2qgo&feature=related

I would like to use the device in Max/MSP as a biofeedback device, using a power spectrum analysis and a spectral centroid analysis.

Thank you,
Krisztian

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