Allofonie

Allophony, also called allofonie in some languages, is the systematic variation of a single phoneme into multiple surface sounds called allophones. These realizations occur in predictable contexts and do not change the meaning of a word. The set of allophones together constitutes the phoneme’s phonetic realization in a given language.

In phonology, a key distinction is between contrastive and non-contrastive variation. If two sounds in the same language can distinguish words, they are different phonemes. If their use can be swapped without affecting meaning, they are allophones of the same phoneme. Allophony often arises from phonetic environment, coarticulation, or historical sound changes.

Common patterns of allophony include complementary distribution, where different allophones occur in mutually exclusive contexts, and free variation, where the choice of allophone is not determined by context. Examples cited in many languages include:

- English stops in word-initial position being aspirated as [pʰ], [tʰ], [kʰ], while in certain clusters (as in sp-, st-, sk-) the same phonemes may be realized with reduced or unaspirated aspiration, producing [p], [t], or [k] in specific after-s cluster contexts.

- American English alveolar /t/ often realized as a tap [ɾ] between vowels when the second vowel is unstressed, as in water, producing a different allophonic realization without creating a new word.

Allophony is described through phonological rules or generalizations about articulatory processes. Understanding allophony helps explain why speakers perceive a consistent sound system despite surface variation and how phonemes implement their audible realizations across contexts.