is no phonemic distinction between long and short vowels, but vowels in stressed open syllables, unless word-final, are long at the end of the intonational phrase (including isolated words) or when emphasized. Adjacent identical vowels found at morpheme boundaries are not resyllabified, but pronounced separately ("quickly rearticulated"), and they might be reduced to a single short vowel in rapid speech. Although Italian contrasts close-mid () and open-mid () vowels in stressed syllables, the distinction is neutralised in unstressed position in which only the close-mid vowels occur. The height of such vowels in unstressed position is context-sensitive; they are somewhat lowered () in the vicinity of more open vowels. The distinction between close-mid and open-mid vowels is lost entirely in a few Southern varieties of Regional Italian, especially in Northern Sicily (e.g. Palermo), where they are realized as open-mid , as well as in some Northern varieties (in particular in Piedmont), where they are realized as mid . Word-final stressed is found in a small number of words: però, ciò, paltò. However, as a productive morpheme, it marks the first person singular of all future tense verbs (e.g. dormirò 'I will sleep') and the third person singular preterite of first conjugation verbs (parlò 's/he spoke', but credé 's/he believed', dormì 's/he slept'). Word-final unstressed is rare, found in onomatopoeic terms (babau), loanwords (guru), and place or family names derived from the Sardinian language (Gennargentu, Porcu). When the last phoneme of a word is an unstressed vowel and the first phoneme of the following word is any vowel, the former vowel tends to become non-syllabic. This phenomenon is called synalepha and should be taken into account when counting syllables, e.g. in poetry. In addition to monophthongs, Italian has diphthongs, which, however, are both phonemically and phonetically simply combinations of the other vowels. Some are very common (e.g. ), others are rarer (e.g. ) and some never occur within native Italian words (e.g. ). None of the diphthongs is, however, considered to have distinct phonemic status since their constituents do not behave differently from how they occur in isolation, unlike the diphthongs in other languages like English and German. Grammatical tradition distinguishes 'falling' from 'rising' diphthongs, but since rising diphthongs are composed of one semiconsonantal sound or and one vowel sound, they are not actually diphthongs. The practice of referring to them as 'diphthongs' has been criticised by phoneticians like Luciano Canepari. Phonotactics