Why do North Americans pronounce "caramel" as "carmel"?

Do you say car-a-mel or car-mel? Is your “fire” closer to fah-yer or fayr?

{Arika Okrent _ Mentalfloss.com _ 3 reasons for syllabically ambiguous words}

• There is a group of words in English that can be pronounced with two different syllable structures, depending on dialect, personal preference, or context of use. While many will insist that one or the other is incontrovertibly correct, there is usually no real basis for pronouncements on the one true syllable structure. Sometimes two things can both be correct. If you need a better authority than me on that, lots of dictionaries accept both pronunciations for all the words discussed below (e.g., Merriam-Webster). What’s more interesting than fighting about who’s right is understanding why these differences arise. There are three processes that result in syllabically ambiguous words.

Two or Three Syllables: caramel, mayonnaise, family, chocolate, camera, different, separate, favorite:

• These words all have a syllable which is often left out of the pronunciation. When we cut a sound out of the middle of a word, it’s called syncope (a three syllable word, sin-ko-pee). O-range becomes ornge, car-a-mel becomes car-mel, in-ter-es-ting becomes in-tres-ting. This pruning of syllables doesn’t happen in some random, haphazard fashion. If a vowel gets chucked, it will be before an r or l (those guys again!) or in some cases a nasal (m or n). It will also be from an unstressed syllable. So the American LA-buh-ra-to-ry becomes lab-ra-to-ry, while the British la-BO-ra-to-ry become la-bo-ra-try.

(mentalfloss.com)

Caramel appears have different pronunciations in different English dialects, the AmE one is just a variant which has been in place for a long time:

• The word caramel can acceptably be pronounced in several accepted ways, including KARR-uh-mel, KARR-uh-muhl, and, in North American English, KAR-muhl. The disappearance of that second syllable -uh- in the final pronunciation seems to have been in the works for a long time. The word has been in English since the 18th century, which it came via French from the Spanish caramel. Order that caramel ice cream sundae however you like!

(blog.oxforddictionaries.com)

From (www.listenandlearnusa.com/blog)