In spoken language, 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 χρονος (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. In phonetics, length or quantity is a feature of sounds that are distinctively longer than other sounds. ...

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. In phonology, minimal pairs are pairs of words or phrases in a particular language, which differ in only one phoneme, toneme or chroneme and have a distinct meaning. ...

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

American English does not have minimal pairs indicating the existence of chronemes or may theoretically said to have only one chroneme; Australian English, on the other hand, does. Australian English is a non-rhotic variety of English spoken by most native-born Australians. ...

Many Indo-European languages, including Classical Latin have distinctive length in consonants, for example in Italian: The Indo-European languages include some 443 (SIL estimate) languages and dialects, including most of the major language families of Europe, as well as many languages of Southwest and South Asia, which belong to a single superfamily. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ...

For example Classical Latin, German, and Thai have distinctive length in vowels. For example in Thai: Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Listen to this article · (info) This audio file was created from the revision dated 2005-07-18, and does not reflect subsequent edits to the article. ...

Almost all Uralic languages, such as Finnish, Hungarian and Estonian have a distinctive moraic chroneme as a phoneme (also justifiably called archiphoneme or epenthetic vowel/consonant). The etymology of the vocalic chroneme has been traced to a voiced velar fricative in the hypothetical Proto-Uralic language, such that [Vɣ] becomes [Vː]. For example, taka- "back-", takka "fireplace" and taakka "burden" are unrelated words. It is also grammatically important; the third person marker is a chroneme (menee "s/he goes"), and often in the spoken Finnish of the Helsinki area there are grammatical minimal pairs, e.g. nominative Stadi "Helsinki" vs. partitive Stadii "at Helsinki". Geographical distribution of Samoyedic, Finnic, Ugric and Yukaghir languages The Uralic languages form a language family of about 30 languages spoken by approximately 20 million people. ... Mora (plural moras or morae) is a unit of sound used in phonology that determines syllable weight (which in turn determines stress) in some languages. ... In human language, a phoneme is a set of phones (speech sounds or sign elements) that are cognitively equivalent. ... In oral language, a phoneme is the theoretical basic unit of sound that can be used to distinguish words or morphemes; in sign language, it is a similarly basic unit of hand shape, motion, position, or facial expression. ... In linguistics, an epenthetic vowel breaks up a consonant cluster that is not permitted by the phonotactics of a language. ... The voiced velar fricative is a type of consonantal sound, used in some spoken languages. ... Proto-Uralic is the ancestor language of the Uralic languages, including the hypothetical families of the Samoyedic languages and the Finno-Ugric languages. ... This article deals with features of the spoken Finnish language, specifically how it is spoken in Greater Helsinki capital region and the cities in the Central Finnish dialectal area, such as Jyväskylä, Lahti, Hyvinkää, and Hämeenlinna. ...

In Finnish, Estonian and Sami languages, there are also two allophonic lengths of the chroneme, half-long and over-long. For example, Finnish imperative anna! "give!" has a short vowel, oma "own" has a half-long vowel, and Annaa "at Anna" has an overlong vowel (without any distinctive tonal variation to distinguish these three). Estonian and Sami also have a three-way distinction in consonants, e.g. lina "bed sheet", linna (half-long 'n') "of the city", linna (over-long 'n') "to the city". Estonian, in which the phonemic opposition is the strongest, uses tonal contour as a secondary cue to distinguish the two; "over-long" is falling as in other Finnic languages, but "half-long" is rising. Sami is a general name for a group of the Uralic languages spoken in parts of Norway, Sweden, Finland and Russia, in Northern Europe. ... In phonetics, an allophone is one of several similar phones that belong to the same phoneme. ...

Finnish also denotes stress principally by adding more length (approx. 100 ms) to the vowel of the syllable nucleus. This means that Finnish has five different physical lengths. (The half-long vowel is a phonemically short vowel appearing in the second syllable, if the first - and thus stressed - syllable is a single short vowel.) The unstressed short vowels are about 40 ms in physical duration, the unstressed long vowels about 70 ms. The stress adds about 100 ms, giving short stressed as 130-150 ms and long stressed as 170-180 ms. The half-long vowel, which is always short unstressed, is distinctively longer than the standard 40 ms.

Japanese is another language in which vowel length is distinctive. For example, biru is a foreign loan word (clipped from a longer form) that means 'building' whereas bīru is a foreign loan word for 'beer'. Using a notion intuitive to a speaker of Japanese, it could be said that more than anything, what differentiates bīru from biru is an extra mora in the speech rhythm that signifies a lengthening of the vowel [i]. It could be said, also, that vowel lengthening—chronemic contrasts—nearly doubles Japanese's rather small inventory of vowel phonemes (though the occurrence of diphthongs also augments vowel counts). Due to native literacy practices, Japanese long vowels are often thought of as sequences of two vowels of the same quality (rather than one vowel of a greater quality or length) since that is how they are sometimes written.

In the case of consonants of Japanese, if treated phonemically, a medial consonant might appear to double, thus creating a contrast, for example, between the word hiki (meaning 'pull' or 'influence') and hikki (meaning 'writing'). In terms of articulation and phonetics, the difference between the two words would be that, in the latter hikki, the doubled [kk] closes the first syllable [hi-] and is realized in the glottis (with some articulation evident in the velum of the mouth, where a /k/ is usually made) while starting the next syllable [-ki] as a [k] articulated and realized as the regular velar sound, while adding one mora to the overall speech rhythm. Hence, among other contrasts, the word hikki is felt to be one mora or beat longer than hiki by a speaker of Japanese.

Reference

http://www.helsinki.fi/puhetieteet/projektit/Finnish_Phonetics/kvantiteetti_eng.htm