[Eeglablist] ERSP Conversion: dB to Microvolts-squared

[Arnaud Delorme]

Dear Chen,

The power spectrum returned in EEGLAB is in unit 10*log10(uV^2/Hz) - see spectopo function output and plot for example.

In Wikipedia you can read below "The number of decibels is ten times the logarithm to base 10 of the ratio of the two power quantities"

http://en.wikipedia.org/wiki/Decibel

So when you compute ERSP and compute the ratio between spectral power at a given time/frequency point and power in the baseline, then take the log10 times 10 (as above), so you actually compute power ratio in dB.

Hope this helps,

Arno

On Nov 22, 2013, at 4:56 AM, Emily Chen <emilychen2013 at gmail.com> wrote:

> Dear all,
> How can I converse the ERSP from dB to microvolts-squared, after the data have been convolved with wavelet?
> Many thanks!
> 
> Sincerely,
> Lihong Chen
> Graduate Student
> Chinese Academy of Sciences, Institute of Psychology
> Lab for Vision and Attention
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