stretching the vowel

Hi,

I have seen writing where people would stretch the vowel or vowels in a word to (what I think is) create a special or specific effect. In that case, only the vowel part can be stretched? Is that because the English language only makes the sound on the vowel part?

e.g.

Gooooood.   

Gooooood
hmmmmm

These sorts of spellings try to mimic speech, where sonorants are sometimes prolonged.

I don't think a spelling like "faileddd" is meant to mimic speech, since obstruents like /d/ cannot be lengthened. The repeated letter in "faileddd" is meant to show that the word is stressed in some other way, I think.