Vowel phonemes Vs letters

Here are some general rules for the sounds but there are exceptional to the rules.

Jones (British phonetic symbols)

Vowel phonemes (Vowel / and consonant letter clusters

1.  / i: /                  (ea, ee, eo, ie, e*) (* very few) 

2.  / I /                    (i, e, o*, u*)

3.  / eI /                  (ace, ade, afe, age, ail, ain, ake, ale, ame, ane, ape, ase,

                              aste, ate, ave, ay)

4.  / e /                  (e, ec, ell, en, et)

5.  / ӕ/                  (a, an, ap, at)

6. / ɑ : /                 (a, ar)

7.  / ɒ /                   (o)

8.  / ʌ /                       (u, o, ou)

9.  / u: /                  (o*, oo, ou, u, ue, ew)

10.  / U/                   (oo, o*, u*)

11.  / əU /                                (o, o – e, oa, ol, ou, ow)

12.  / ɔ : /                (a, al, all, ar, au, aw, oar, or, our*)

13.  /3 : /                 (ear, er, ir, ur)

14.  / ə /                  (unstressed syllables à a, ar, e, er, re#, i, o, or, u, ure) 

                               (re# the last syllable of the words)

15.  / aI /                 (i, ice, ide, ife, igh(t), ike, ile, ime, ind, ine, ite, ie, y)

16.  / aU /                (ou, ow)

17.  / ɔI  /                     (oi, oy)      

18.  / Iə/                  (ear, eer, ere, eir, ier, ia, ion)

19.  /eə/                  (ear, air, are, eir)

20.  /Uə/                  (oor, our, ur, ua)

For unstressed syllables, the vowel letters have either / I/ or / ə / sound.