My Dad used to say fil-im... and "De-troy-it" for Detroit... this was once common in Toronto... but you don't think you hear it so much now... although I now live in Atlanta where if you don't say 'vee-hickle' or 'thee-ayter" (unvoiced 'th') people look at you funny.

Since I moved down here I had to stop saying 'eh', 'prohcess' and 'prohgress'... but funnily enough I had to start saying 'prohduce' for fruit and veggies.

goofy has it bang on... the voiceless consonant is responsible for the 'raising' of the vowel.

The difference can also be heard in the following example:

"I scream" vs "ice cream"... where the "ai" diphthong in "ice cream" is raised while it is not in "I scream".