Why is it not "Bốn mươi bốn"?
Tư is another way of saying 4.
it can be either, check the tips and notes
Why is the huyền tone not over mười?
please follow this link for further explanations.
Still at this point I would need that the speaker would speak slower :(
I hear "bon - me - too", I cannot distinguish the triptong
The audio is way too fast. Other courses allow you to slow the audio. Not sure why that feature isnt in vietnamese
Is bốn and tư interchangeable?
not always but as the unit in a ten-unit pair, yes.
Is this the same for both north and sound vietnamese?