In the 'Type what you hear' exercise, the voice seems to say either φι φι ιώτα or θι θι ιώτα - it's not possible to tell which. But the 'correct' answer does not include ιώτα, which is the only clear word, and so we are doomed to be marked wrong whatever we write! I was trying to write what I heard, not what I thought the spelling was.
Are you doing the ABC Skill. YOu seem to know the alphabet very well. That skill has many problem and is one of the main reasons we have created the New Tree. That and the audio which Duo added that turned out to be defective (we are now testing anew audio system for use with the New Tree).
So, to put it briefly there is nothing to be gained by struggling with the ABC skill. Check out the comment above yours.
It is "FEE" Greek pronunciation is really straight forward (ok one or two exceptions).
What I hear on the slow version is not very clear but that is due to the fact that the audio is a computer generated voice. Go here for native speakers.
Also, check these out:
TIPS TO HELP YOU LEARN + HOW TO REPORT A PROBLEM
And the Greek Forum here with more links.
For those of you who already know the Greek alphabet, what each letter looks like, how it's pronounced, the diphthongs, the double consonants, where to find it on the keyboard etc then just move on to the next Skill.
If you want to brush up use this:
HINTS ON HOW TO LEARN THE MODERN GREEK ALPHABET and HOW TO GET THE GREEK KEYBOARD https://forum.duolingo.com/comment/23430853