Short Vowels
   

a is a low front open vowel, very close to [æ]. It may be compared with [-a-] in ‘cat’, but without the [-y-] off-glide; it is also very close to [á]. (Compare and contrast the English man and Persian من mán ‘I’).
e is an open-mid front vowel, very close to [ɛ]. It may be compared with [-e-] in “let”.
o is a close-mid to open-mid back vowel. It may be compared with the [-o-] in the second syllable of ‘colonize’. Normally, English /o/ is accompanied by a “w” off-glide (as in ‘roller’); this is not the case in Persian.

Listen to the short vowels in the following set:

head a as in sar سَر
secret e as in serr سِرّ
slippery o as in sor سُر

When short vowels are followed by a consonantal cluster within the same syllable, they are lengthened; as in the following words:

leaf ba׃rg بَرگ
loose ha׃rz هَرز
he/she/it did ka׃rd کرد
affection mehr مِهر
inquiry po׃rse پُرس
cold sa׃rd سَرد
city sha׃hr شَهر
fear ta׃rs تَرس
expense xa׃rj خرج
bear xe׃rs خِرس
dry xo׃šk خُشک
yellow za׃rd زَرد
chest, breast; up; fruit bar بَر
every har هَر
deaf kar کر
mist, fog meh مِه
full por پُر
head sar سَر
king shah (short /a/) شَه
wet tar تَر
donkey xar خَر
(colloquial) throat, esophagus xer خِر
happy xoš خُوش
gold zarr زَرّ