In lesson 11.1, at about 22min 15sec, Sandra & Matthias relate the difference in the words Armer and Arme depending on whether we are addressing a man or a woman.
They repeat these several times, but I confess I can hear very little difference. Du Arme is perhaps marginally more clipped than du Armer, (to my ears) but in normal speed speech I suspect it would be difficult to tell which has been said.
I've come across similar instances with words taking the endings -e or -er elsewhere in the course.
Would a native German speaker be able to tell the difference easily, and how important is it?