What is the unit of the psds when computing mne.time_frequency.psd_array_welch ?

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1

Hi there!
I am trying to calculate the PSD like this:
psds, freq = mne.time_frequency.psd_array_welch(epochs, sfreq=epochs.info['sfreq'], fmin = 2, fmax = 40, n_fft = int(2*epochs.info['sfreq']), n_overlap= int(epochs.info['sfreq']/2), verbose= 'warning')

It returns me the psds and also the frequency bins, so all seems well so far.
But the values returned are extremely small (e.g. 3.58183353e-12, 3.12845131e-14, ā€¦)
So Iā€™m wondering, what kind of unit does the returned psds have?
Is it \mu ^2 V/Hz?

Thanks for your help already!

2

it should be V^2/Hz

multiply your values by 1e12 to get \muV^2/Hz

See eg plot in https://mne.tools/stable/auto_tutorials/time-freq/10_spectrum_class.html#sphx-glr-auto-tutorials-time-freq-10-spectrum-class-py

Alex

3

How did I not find this summary :woman_facepalming: ā€“ thank you so much! Best, Annina