In Dialects^x, Vowels^x, Intonations^x

I don't think it's called intonation. It's allophonic vowel length: vowel phonemes are realized as longer vowel allophones before voiced consonant phonemes in the coda of a syllable. This is found in all dialects of American English. Some American dialects have some phonemic vowel distinctions as...

Hi, Americans use different intonation for vowel sounds in one-syllable words, according to the final consonant (whether it is voiced or unvoiced). Examples: Bit - Bid (the vowel in "bid" sounds different, it is on two levels of intonation) niece - knees (the vowel in "knees" is on two levels)...