Question about normalization before estimate the spectrum I work with a Electrophysiologist Team and i have seen something who interrogate me (i'm a noobs in DSP).

They acquires a signal into a brain structure (an LFP to be precise) :


in a first time they apply a zscore(standard score) normalization on the raw data
then they computes a spectral estimation with a CWT(continuous wavelet transform, morlet in this case)


Is that not a bias to use a normalization like a zscore before estimate the spectrum(or to do anything else in DSP)? Or is that a common way to deal?

Thank you for a potential answer.

Nicolas
Most standard time-frequency-scale transforms are consistent with mean/standard-deviation corrections. In a more pedantic ways, linear transforms can cope well with affine transformations, in the shape of:

$$x' =  \frac{x-a}{b}$$

of which the $z$-score is a special case. The potential bias can easily be inverted. 

So as long as the representation remains linear, and somehow preserves energy, such a normalization does not sound so harmful to me. With CWT tools, you can compare shapes. However, you loose amplitude, stuff becomes relative