In phonetics, clipping is the process of shortening the articulation of a phonetic segment, usually a vowel. A clipped vowel is pronounced more quickly than an unclipped vowel and is often also reduced.
Particularly in Netherlands Dutch, vowels in unstressed syllables are shortened and centralized, which is particularly noticeable with tense vowels; compare the /o:/ phoneme in konijn (phonemically /ko:'n?in/) 'rabbit' and koning (phonemically /'ko:n/) 'king'.
In weak forms of words, e.g. naar and voor, the vowel is frequently centralized: [n?:r, v?:r], though further reduction to [n?, v?] or [nr?, vr?] is possible in rapid colloquial speech.
Many dialects of English (such as Australian English, General American, Received Pronunciation, South African English and Standard Canadian English) have two types of non-phonemic clipping: pre-fortis clipping and rhythmic clipping.
The first type occurs in a stressed syllable before a fortis consonant, so that e.g. bet ['b?t] has a vowel that is shorter than the one in bed ['bd]. Vowels preceding voiceless consonants that begin a next syllable (as in keychain /'ki:.t?e?n/) are not affected by this rule.
Rhythmic clipping occurs in polysyllabic words - the more syllables a word has, the shorter its vowels are, so that e.g. the first vowel of readership is shorter than in reader, which in turn is shorter than in read.
Clipping with vowel reduction also occurs in many unstressed syllables.
Because of the variability of vowel length, the ⟨:⟩ diacritic is sometimes omitted in IPA transcriptions of English, so that words such as dawn or lead are transcribed as /d?n/ and /lid/, instead of the more usual /d?:n/ and /li:d/. Neither type of transcription is more correct as both convey exactly the same information, though transcription systems that do use the length mark make it more clear whether a vowel is checked or free - compare the length of the RP vowel /?/ in the word not as opposed to the corresponding /?/ in Canadian English, which is typically longer (like RP /?:/) because Canadian /?/ is a free vowel (checked /?/ is very rare in North America as it relies on a three-way distinction between LOT, THOUGHT and PALM) and thus can also be transcribed as /?:/.
The Scottish vowel length rule is used instead of those in Scotland and sometimes also in Northern Ireland.
Many speakers of Serbo-Croatian from Croatia and Serbia pronounce historical unstressed long vowels as short, with some exceptions (such as genitive plural endings), so that e.g. the name Jadranka is pronounced [jâdra?ka], rather than [jâdra:?ka].