Chroneme

In linguistics, a chroneme is a basic, theoretical unit of sound that can distinguish words by duration only of a vowel or consonant. The noun chroneme is derived from Greek χρόνος (chrónos, time), and the suffixed -eme, which is analogous to the -eme in phoneme or morpheme. However, the term does not have wide currency and may be unknown even to phonologists who work on languages claimed to have chronemes.

Most languages have differences in length of vowels or consonants, but in the case of most languages it would not be treated phonemically or phonologically as distinctive or contrastive. Even in those languages which do have phonologically contrastive length, a chroneme is only posited in particular languages. Use of a chroneme views /aː/ as being composed of two segments: /a/ and /ː/, whereas in a particular analysis, /aː/ may be considered a single segment with length one of its features. This may be compared to the analysis of a diphthong like [ai] as a single segment /ai/ or as the sequence of a vowel and consonant: /aj/.

For the purposes of analysis of a chronemic contrast, two words with different meaning that are spoken exactly the same except for length of one segment are considered a minimal pair.

The International Phonetic Alphabet (IPA) denotes length by doubling the letter or by diacritics above or after the letters:

American English does not have minimal pairs indicating the existence of chronemes or may theoretically be said to have only one chroneme. Some other dialects such as Australian English have contrastive vowel length, but it is not analysed as the consequence of a chroneme.

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