Morse code is really just a simple digital signal. So either there is sound (True) or there isn't (False). Is there a module that can return whether there is noise present above a specified audio level (be it either volume or frequency)? If so, then the dits and dahs can be approximated based on how often True is returned within a given length of time. Then all that would be required to insure accuracy would be to specify the estimated wpm to scale the approximations.