Smalley also described three "vowels with offglides" that he treated as monophthongs, namely /iə/, /ɨə/ and /uə/, for a total of 17 vowel phonemes. All 17 vowels may occur in closed syllables and all but ɨə have been found in open syllables. With 14 basic vowel positions, and having more back vowels than front, Northern Khmer is atypical. By contrast, standard Central Khmer only has 9 or 10 basic vowel positions, depending on the analysis.