The actual exact pronunciation of the vowels in Levantine is, as in English, one of the many indicators of regional dialect. The most important thing for an initial learner is trying to approximate the sounds and keep the various different vowels distinct. You can worry about getting them closer to native pronunciation later when you have people to imitate.
One of the most important things to worry about is length – you have to make your long vowels longer than your short vowels. The five long vowels are aa ii uu ee oo (ee and oo correspond to ay and aw in fuSHa and probably sound to you, if you are a native English speaker, like the vowels in ‘late’ and ‘wrote’ and should not be confused with our vowels in ‘beet’ and ‘boot’).
كاتب kaatab ‘he wrote to’ and كتب katab ‘he wrote’ are distinct from one another.
مين miin ‘who’ and من min ‘from’ are distinct from one another.
دوق duu2 ‘taste (it)!’ and دق du2(2) ‘hit (it)!’ are distinct from one another.
In fuSHa, there are almost no long final vowels that are not followed by a consonant. If you’re pronouncing fuSHa right, then شهداء shuhadaa2 should have a long vowel in its last syllable, but ذكرى dhikra, despite being written with one, has a final short vowel (unless you learnt Tajwiid or something, in which case good for you). The only exception is in words like مباراة mubaaraa(h) where there is a final taa marbuuTa that is not pronounced. This is mostly the same in Levantine, with one exception: when we attach the pronoun ـه ‘he’ to a final vowel, that vowel is lengthened and the -h is dropped.
درسي drési ‘study!’ is distinct from درسيه drésii ‘study it!’
مصاري maSaari ‘money’ is distinct from مصاريه maSaarii ‘his money’.
Finally, in Palestinian and Jordanian, long vowels which are not stressed are usually shortened: مفاتيح mafatii7 ‘keys’ (not mafaatii7 as in Syrian and as the spelling suggests).
Short vowel é
In Palestinian and Jordanian, short u/i are distinct at all times. In Syrian and Lebanese, however, short u/i/o/e do not commonly occur in stressed syllables, merging into a sound we write with é (بدرس bédros ‘I study’, كتبو ktébu ‘write!’, شغل shégh@l ‘work’). This sound also occurs in some unstressed syllables (قدام 2éddaam ‘in front of’).
This sound is pronounced in a variety of ways depending quite predictably on the sounds around it. The two most common realisations in Damascene are as what is called in linguistics a schwa (approximately the central-ish vowel sound in English ‘but’) and as a kind of short i (similar to in English ‘pit’). This means that كنت ‘I was’ sounds like kint, whilst حط ‘put (it)’ sounds sort of like English ‘hut’.
Note that this sound is being replaced in some words by its higher-register (fuSHa) equivalent. حب for example (‘love’) is pronounced both 7ébb and 7ubb.
Helping vowel @
Whilst initially Shami allows lots of consonant clusters, finally and across word boundaries it is less keen on them and usually breaks them up with a helping vowel @. This vowel cannot be stressed and the word takes stress as though it wasn’t there (تعلمت t3allam@t ‘I learnt’, مشمشه mésh@mshe ‘apricot’). Exactly which final consonant clusters are broken up depends on the speaker and the dialect, but here are some examples:
فيلم fil@m ‘film’
كنت kén@t ‘I was’
بحر ba7@r ‘sea’
In Syrian and Lebanese this vowel is pronounced exactly like é. In Palestinian and Jordanian, where there is no é vowel, it is pronounced differently depending on the real (non-epenthetic) vowel before it. In verbs it is always e, but in nouns it is typically e after a i e and o after o u:
فلم filem ‘film’
كنت kunet ‘I was’
عذر 3uzor ‘excuse’
The helping vowel is typically inserted into final consonant clusters when they appear before a pause or if the next word begins with a consonant which creates an unpleasant consonant cluster:
الفيلم يلي شفتو élfil@m yalli shéfto ‘the film I saw’
رحت لعندو ré7@t la3éndo ‘I went to his house’
اخدت دوى؟ اي اخدت akhad@t dawa? ee akhad@t ‘have you had some medicine? yeah I’ve had some’
It can also be inserted in between words. This typically happens if the next word begins with a consonant cluster itself:
انبسطت كتير mbasaTT @ktiir ‘I had a really good time’
كنت اشتريت ként @shtareet ‘I had bought’
Unstressed o e i u in a final syllable are usually dropped when a suffix beginning with a vowel is added:
كاتب كاتبه كانبين kaateb, kaatb-e, kaatb-iin ‘writer, writers’
شرب, شربت, شربو shéreb, shérb-et, shérb-u ‘he drank’, ‘she drank’, ‘they drank’
قالت, قالتلكن 2aalet, 2aalt-élkon ‘she said’, ‘she said to you’
Unstressed a is not normally dropped, except when the third person singular feminine suffix -et, -at is added:
كتبت, كتبو katb-et/katb-at, katab-u ‘she wrote’, ‘they wrote’
Vowel dropping can also occur across word boundaries when words are pronounced as part of a tight unit
شافت الفيلم shaaf(e)t élfilm ‘she saw the film’
مدرسة محمد madras(e)t @m7ammad ‘Muhammad’s school’
Adding some suffixes results in a stress shift (according to the regular rules of stress). If this results in an unstressed e o i u becoming stressed, in Syr/Leb it changes into an é:
بيكتب بيكتبلك byéktob, byéktéblak ‘he writes’, ‘he writes for you’
بتمسك, بتمسكها btémsek, btémsékha ‘you grab, you grab it’
When the –l- suffixes are added to a hollow verb, its long vowel is shortened. If the long vowel is ii or uu, then in Syr/Leb it is shortened to é:
بقول, بقللك bi2uul, bi2éllak ‘he says’, ‘he says to you’
When suffixes are added to nouns and adjectives ending in -i, it never drops (as in fuSHa ماشي ماشون maashi maashuun for example). Where the suffix is a nisba adjective suffix, it becomes -iyy-:
حلبي, حلبيّة 7alabi, 7alabiyy-e ‘Aleppan’, ‘Aleppans’
In most other cases it becomes -y-:
ماشي ماشيين maashi, maashyiin ‘walking’
مستوي مستوية méstewi, méstéwye ‘cooked’
There are a few exceptions, however, like form I defective passive participles:
مطفي, مطفية méTfi, méTfiyye ‘switched off’