smacks forehead This is so absurd it’s almost funny.
Amadeus, you are quite right in pointing out that our friend blutoonwithcarrotandnail, likely an Anglophone, has been taught the “English” pronunciation of Latin, a pronunciation inherently incorrect. This is why he is having such trouble and coming to ask all these very good questions.
For indeed, there are only five vowels in Latin: A, E, I, O, U. The quality, that is, the sound of A, I, and U does not change. They somewhat resemble these English vowels:
A: father
I: machine
U: true
E and O, when long or short, have slightly different sounds. It is impossible to describe them properly with English phonetics, since there are very few accents in our language which possess similar sounds (though Scottish and Irish accents tend to be pretty clean). In any case, Latin vowels are identical to Italian vowels, if that helps. In the meantime, for E, I suggest to our friend to err towards the ‘e’ in “get,” but to smile broadly while making the sound. For the O, try to make a very closed version of the British vowel “hot.”
C?re Amadīue, just as blutoonwithcarrotandnail’s (presumed) Anglophonic origins prevent him from understanding Romance vowels just yet, it would seem that being by birth an Hispanophone you may not be able to distinguish the (often unattractive) complexity of English vowels. For that website you noted seems to be using the English pronunciation of Latin (the same appears at the beginning of Wheelock, that damnable pseudoergon), for the vowel in “boot” is very, very different from the vowel in “foot.” The vowel in “foot” is closer to a schwa, while the sound in “boot” is closer to the true Latin sound of the vowel U, and thus closer to Spanish, Italian, et ceteras. In my experience, most English teachers in Spain and Italy have very strong accents, and in these accents no distinction is made between “foot” and “boot.” It is possible you yourself, amīce, have come to understand these English sounds in the same manner.
To the point, Latin U is always pronounced in a way similar to the ‘u’ in my name: Luke (this is not true for the British accents, unfortunately). When it is long, it is held for a longer period of time. When it is short, it is held for a shorter period of time. There is no difference in quality, only in quantity.
blutoonwithcarrotandnail, I would be delighted to continue this conversation with you by means of Skype, a free phone-calling service through the internet. By ear and by voice is the only means of acquiring any true sense of these sounds. The written word fails us.