log base in log-power spectral features Is the log in log-power spectral features natural logarithm, or common log of base 10? does it even matter?
I found sources for how to calculate it, but they all call it 'log'.
no one mentions the base for the logarithm.

The answers provided for this question were insightful though I checked a few papers and finally realized that for log power spectral features (speech separation use cases), natural logarithm is used. though this is a very specific use case and both common base-10 log and natural log can be used in speech processing depending on the application.
It's not particularly important since the different bases just result in a different overall scale factor, but the basic shapes are the same.

This being said, any actual numbers need to be defined with a specific bases otherwise it's ambiguous. The most common is the $dB$ which (for power) is defined as 
$$L = 10 \cdot log_{10}(P/P_0)$$

i.e. it uses base 10.