Hi everyone,

I want to calculate the average of PSD in a determined epoch, here is the code:

```
spectrum = epochs[62].compute_psd(method="welch",picks='C3_M2',fmin=12,fmax=30)
PSD, freqs = spectrum.get_data(return_freqs=True)
spectrum.plot()
```

The result would be like following:

As I want to take the average first I need to retrieve the Amplitude which is in (dB), like the first point which is about 123, but after I convert the PSD to dB, I have a weird data:

```
10 * np.log10(PSD)
```

which I got

```
array([[[ 3.13982779, -3.86176929, 6.85332206, 4.17123814,
4.93127581, 7.4832183 , 1.12038761, 7.68291897,
6.40367422, 6.24721421, 6.57093037, 6.4076177 ,
5.45691297, -1.51206827, 6.76020133, 6.69414559,
9.51026022, 9.10557663, 5.63438618, 3.24274636,
-5.68817689, 2.77028109, 7.11039496, 8.68978814,
9.45466904, 5.62792485, 4.2303355 , 4.14692724,
3.25922632, 4.33403963, 5.39546468, 0.92007031,
3.73590139, 5.64315007, 4.32840387, 4.41999972,
0.74850308, 1.92540129, 5.95650245, 4.2219239 ,
4.86983096, 7.17304789, 6.39538512, 5.62660172,
3.48318393, 0.52069617]]])
```

But the element doesnβt match the figure which would be data around 116 and 128. What formulate should I use to get the y-axis values?

Also could you please help me with how can I calculate the subsurface of the PSD plot, somewhere I read I should calculate the RMS of PSD? Is this correct, and how can I calculate that?

Thanks in advance