// extracting whatever stats we want. In this case, mean/std/lowest/highest, and the same on the first derivative - excluding MFCC0 as it is mostly volume, keeping MFCC1-12
// extracting whatever stats we want. In this case, mean/std/lowest/highest, and the same on the first derivative - excluding MFCC0 as it is mostly volume, keeping MFCC1-12