Compensatory lengthening inphonology andhistorical linguistics is the lengthening of avowel sound that happens upon the loss of a followingconsonant, usually in thesyllable coda, or of a vowel in an adjacentsyllable. Lengthening triggered by consonant loss may be considered an extreme form offusion (Crowley 1997:46). Both types may arise from speakers' attempts to preserve a word'smoraic count.^[1]

An example from thehistory of English is the lengthening of vowels that happened when thevoiceless velar fricative/x/ and itspalatalallophone[ç]^[2] were lost from the language. For example, in theMiddle English ofChaucer's time the wordnight was phonemically/nixt/; later the/x/ was lost, but the/i/ was lengthened to/iː/ to compensate, causing the word to be pronounced/niːt/. (Later the/iː/ became/aɪ/ by theGreat Vowel Shift.)

Both theGermanic spirant law and theIngvaeonic nasal spirant law show vowel lengthening compensating for the loss of a nasal.

Non-rhotic forms of English have a lengthened vowel before a historical post-vocalic*/r/: in Scottish English,girl has a short/ɪ/ followed by a light alveolar/r/, as presumably it did in Middle English; in Southern British English, the*/r/ has dropped out of the spoken form and the vowel has become a "long schwa"[əː].

Compensatory lengthening in Classical Hebrew and Aramaic is dependent on the class of consonant which follows the prefix (definite article in Hebrew and prefix waw-hahipukh in both languages).

E.g. (using the Hebrew definite article [hey with pataḥ plus dagesh in following consonant]):^[3]

• Beforeע‎ andא‎ it is usually [hey with qametz].
• Beforeח‎ andה‎ it is usually [hey with pataḥ]. If it is pretonic it may be [hey with qametz].
• But when it is propretonic, whatever the guttural, it will usually be [hey with segol].

Compensatory lengthening is very common inAncient Greek. It is particularly notable in forms wheren ornt comes together withs,y (= ι̯), ori. The development ofnt +y was perhaps thus:

• *mont-yă →montsa (palatalizationty →ts) → mõtsa (nasalization and vowel lengthening) → mõssa → mõsa (shorteningss →s) → mōsa (denasalization, retention of long vowel) = μοῦσα "muse"

Forms with this type of compensatory lengthening include the nominative singular and dative plural of many participles, adjectives, and nouns, the3rd personplural ending forpresent andfutureactive of allverbs, and the 3rd person singular present ofathematic verbs:

• *πάντ-ς →πᾶς "every, whole" (masculinenominative singular)^[4]
• *πάντ-ι̯ᾰ → *πάντσα → πᾶσα (feminine)
• *πάντ-σι → πᾶσι (masculine/neuter dative plural)
• compareπαντ-ός (m./n. genitive singular)
• *όντ-ι̯ᾰ → *όντσα → οὖσα participle "being" (feminine nominative singular)^[5]
• *οντ-ίᾱ → *ονσία → οὐσία "property, essence"
• compareὀντ-ός (m./n. genitive singular, from participle ὤν "being",)
• Doricἄγ-ο-ντι → ἄγοντσι →Attic/Ionicἄγουσι "they drive"
• Doricφα-ντί → *φαντσί → Attic/Ionicφᾱσί "they say"^[6]

In the evolution of the modernIndo-Aryan languages, there is a first stage in which consonant clusters with dissimilar consonants preceded by a short vowel undergo assimilation resulting in consonant clusters with similar consonants. In the second stage, the first consonant of the cluster or geminate was lost, which was accompanied by the lengthening of that vowel and sometimes additional nasalization. InPunjabi, only the first stage occurred, while most of the other modern Indo-Aryan languages underwent the second stage as well.

The phonemes /ɣ/, /ʕ/, and /h/ were all vowelised inMaltese during a period spanning from the 18th to 20th centuries (except in word-final position where they were generally merged with /ħ/). In the spelling they are still represented, however, asgħ for historic/ɣ/ and/ʕ/, andh for historic/h/. These vowelised consonants lengthen adjacent short vowels, i.e. both preceding and following ones. For example,jagħmel ("he does"), formerly[ˈjaʕ.mɛl], now pronounced[ˈjaː.mɛl], andjitgħallem ("he learns"), formerly[jɪtˈʕal.lɛm], now pronounced[jɪˈtaːl.lɛm].^[7]

Thevoiced velar fricative (/ɣ/), has undergone a sound change inTurkish by which the consonant was completely lost and compensatory lengthening of the preceding vowel occurred. Even though the sound has been completely lost in standard Turkish, the sound change is not yet complete in someTurkish dialects and the corresponding velar fricative found in cognate words in the closely relatedAzerbaijani language and the Turkish-influencedCrimean Tatar language. The previous consonantal nature of the sound is evinced by earlier English loanwords from Turkish, such asyogurt/yoghurt (modern Turkishyoğurt,Turkish pronunciation:[joˈurt]) andagha (modern Turkishağa,Turkish pronunciation:[a'a]).

The letterĞ inTurkish alphabet and its counterpart⟨غ⟩ inOttoman Turkish were once pronounced as/ɣ/. In modern Turkish, Ğ is used either as asilent letter indicating asyllable break or as avowel lengthener for the preceding sound. It can also indicate the/j/ sound, if the preceding vowel is an/e/.

• Mora
• Phonological history of English
• Ancient Greek nouns

• Crowley, Terry. (1997)An Introduction to Historical Linguistics. 3rd edition. Oxford University Press.
• Smyth,Greek Grammar onCCEL.