Obligatory Contour Principle

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In phonology, the Obligatory Contour Principle is a general principle stating that two identical features should not occur in succession.

Examples:

• A sequence of two identical vowels must either be broken up by hiatus or coalesce into a long vowel; they may not form a diphthong.
  • Similarly, diphthongs of the type /ij/ or /uw/ are practically unheard of; /ji/ and /wu/ are also prohibited by several languages, or at least do not contrast with /i/ and /u/ (English is one exception: cf. yeast vs. east)
• In tonal languages, adjacent syllables may not be marked for the same tone; in cases where this situation is found phonetically, it is analysed in terms of tone spreading, word tone or pitch accent.
• Languages commonly prohibit clusters of similar consonants, especially of two sibilants.

The OCP also accounts for the cross-linguistic rarity of roots containing several identical consonants (with the exception of baby-talk words such as mama, papa, nana, daddy, booboo, peepee, titty, which may fall under primitive reduplication).

The motivation of sound changes involving dissimilation may be included under the OCP.

This article is part of a series on Phonetics and Phonology. Affricate * Allophone * Aspiration * Bilabial consonant * Buccal * Coronal consonant * Dental consonant * Fricative * Heng * Manner of articulation * Obligatory Contour Principle * Palatalization-split * Phoneme * Phoneme hole * Phonological feature * Rhotacism * Spirant * Stop * Syllable structure * Velar consonant * * Phonetic alphabets * Phonetic Segments