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 ?????? (chronos,
time), and the suffixed
-eme, which is analogous to the
-eme in
phoneme. However, this term does not have wide currency, and may even be unknown 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 /a?/ as being composed of two segments /a/ and /?/, whereas in a particular analysis, /a?/ may be a 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 consonant and vowel /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
