|Sound change and alternation|
Germanic languages 
L-vocalization occurred since Early Modern English in certain -al- and -ol- sequences before coronal or velar consonants, or at the end of a word or morpheme. In these sequences, /al/ became /awl/ and diphthonged to /ɑul/, while /ɔl/ became /ɔwl/ and diphthonged to /ɔul/.
At the end of a word or morpheme, this produced all, ball, call, control, droll, extol, fall, gall, hall, knoll, mall, pall, poll, roll, scroll, small, squall, stall, stroll, swollen, tall, thrall, toll, troll and wall. The word shall did not follow this trend, and remains /ˈʃæl/ today.
Before coronal consonants, this produced Alderney, alter, bald, balderdash, bold, cold, false, falter, fold, gold, halt, hold, malt, molten, mould/mold, old, palsy, salt, shoulder (earlier sholder), smolder, told, Wald, Walter and wold (in the sense of "tract of land"). As with shall, the word shalt did not follow this trend, and remains /ˈʃælt/ today.
Words like fault and vault did not undergo L-vocalization, but rather L-restoration, having previously been L-vocalized independently in Old French and lacking the /l/ in Middle English, but having it restored by Early Modern English. The word falcon existed simultaneously as homonyms fauco(u)n and falcon in Middle English. The word moult/molt never originally had /l/ to begin with, instead deriving from Middle English mout and related etymologically to mutate; the /l/ joined the word intrusively.
This L-vocalization established a pattern that would influence the spelling pronunciations of some relatively more recent loanwords like Balt, Malta, polder, waltz and Yalta. It also influenced English spelling reform efforts, explaining the American English mold and molt vs. the traditional mould and moult.
But certain words of more recent origin or coining do not have the change and retain short vowels, including Al, alcohol, bal, Cal, calcium, doll, gal, Hal, mal-, Moll, pal, Poll, Sal, talc, and Val.
In most circumstances, the L-vocalization stopped here. But it continued in -alk and -olk words, with the /l/ disappearing entirely in most accents (with the notable exception of Hiberno-English). This change caused /ɑulk/ to become /ɑuk/, and /ɔulk/ to become /ɔuk/. Even outside Ireland, some of these words have more than one pronunciation that retains the /l/ sound, especially in American English where spelling pronunciations caused partial or full reversal of L-vocalization in a handful of cases:
- caulk/calk can be /ˈkɔːlk/ or /ˈkɔːk/.
- falcon can be /ˈfælkən/, /ˈfɔːlkən/ or /ˈfɔːkən/.
- yolk can be /ˈjoʊlk/ or /ˈjoʊk/. yoke as /ˈjoʊk/ is only conditionally homophonous.
The Great Vowel Shift changed the L-vocalized diphthongs to their present pronunciations, with /ɑu/ becoming the monophthong /ɔː/, and /ɔu/ raising to /ou/.
The loss of /l/ in words spelt with -alf, -alm, -alve and -olm did not involve L-vocalization in the same sense, but rather the elision of the consonant and usually the compensatory lengthening of the vowel.
More extensive L-vocalization is a notable feature of certain dialects of English, including Cockney, Estuary English, New York English, New Zealand English, Pittsburgh and Philadelphia English, in which an /l/ sound occurring at the end of a word or before a consonant is pronounced as some sort of close back vocoid, e.g., [w], [o] or [ʊ]. The resulting sound may not always be rounded. The precise phonetic quality varies. It can be heard occasionally in the dialect of the English East Midlands, where words ending in -old can be pronounced /oʊd/. KM Petyt (1985) noted this feature in the traditional dialect of West Yorkshire but said it has died out. However, in recent decades l-vocalization has been spreading outwards from London and the south east, and it is probable that it will become the standard pronunciation in England over the next one hundred years.
In Cockney, Estuary English and New Zealand English, l-vocalization can be accompanied by phonemic mergers of vowels before the vocalized /l/, so that real, reel and rill, which are distinct in most dialects of English, are homophones as [ɹɪw].
In the accent of Bristol, syllabic /l/ vocalized to /o/, resulting in pronunciations like /ˈbɒto/ (for bottle). By hypercorrection, however, some words originally ending in /o/ were given an /l/: the original name of the town was Bristow, but this has been altered by hypercorrection to Bristol.
African-American Vernacular English dialects may have L-vocalization as well. However, in these dialects, it may be omitted altogether (e.g. fool becomes [fuː]. Some English speakers from San Francisco - particularly those of Asian ancestry - also vocalize or omit /l/.
Middle Scots 
In early 15th century Middle Scots /al/ (except intervocalically and before /d/), /ol/ and often /ul/ changed to /au/, /ou/ and /uː/. For example all changed to aw, colt to cowt, ful to fou (full) and the rare exception hald to haud (hold).
|This section requires expansion. (September 2012)|
In early Middle Dutch, /ul/, /ol/ and /al/ merged and vocalised to /ou/ before a dental consonant (/d/ or /t/). This resulted in, for example:
- oud "old" < ald
- hout "wood" < holt
- Wouter, a name < Walter
The combination /yl/, which was derived from /ol/ or /ul/ through umlaut, was not affected by this change. This resulted in alternations that still survive in modern Dutch:
- goud "gold", but gulden "golden"
- schout "sheriff", but schuld "guilt, debt"
Ablaut variations of the same root also caused alternations, with some forms preserving the /l/ and others losing it:
- houden "to hold", past tense hield
- wouden "wanted" < wolden, past tense of willen "to want"
Analogy has caused it to be restored in some cases, however:
- wilden reformed next to older wouden
- gelden "to apply", past tense golden, earlier gouden
Swiss German 
In Bernese German, a historical /l/ in coda position has become [w], a historical /lː/ (only occurring intervocalically) has become /wː/, whereas intervocalic /l/ persists. The absence of vocalization was one of the distinctive features of the upper class variety which is not much spoken anymore. For example, the German name of the city of Biel is pronounced [ˈb̥iə̯w].
This type of vocalization of /l/, however, such as [sɑwts] for Salz, is a phenomenon recently spreading in many Western Swiss German dialects, with the Emmental as centre.
Romance languages 
- Neapolitan shows a pattern similar to French, where [l] is vocalized, especially after [a]. For example, vulgar Latin altu > àutə; alter > àutə; calza > cauzétta (with diminutive suffix). In many areas the vocalized [l] has evolved further into a syllabic [v], thus àvətə, cavəzetta.
- West Iberian languages such as Spanish and Portuguese had similar changes to those of French, though they were less common; for example Latin alter became autro and later otro (es) or outro (pt), while caldus remained caldo, and there were also some less standard shifts, like vultur to buitre (es) or abutre (pt).
- In Brazilian Portuguese, historical [ɫ] (/l/ in the syllable coda) has become [u̯ ~ ʊ̯] (the vowels /u/ and /i/ only have [ʊ] and [ɪ] as allophones in southern dialects, such as that of São Paulo) for most dialects, including all urban, metropolitan ones. For example, the words mau (bad as a state of being, poor, wrong, mischievous) and mal (bad as a quality, evil, ill, hurt, harm) are both pronounced [ˈmaw], while in European Portuguese the latter is pronounced [ˈmaɫ]. This homophonous pair is clearly distinguishable by context, though: the opposite of mau is bom (good as in good and bad taste) [ˈbõː], while the opposite of mal is bem (good as in good versus evil) [ˈbẽ ȷ̃].
In pre-Modern French, [l] vocalized to [w] in certain positions:
- between a vowel and a consonant, as in Vulgar Latin caldum "warm, hot" > Old French chaud /tʃaud/
- after a vowel at the end of a word, as in Vulgar Latin bellu(m) > Old French bel > Old French beau /be̯au̯/ "beautiful" (masculine singular; compare the feminine bele /bɛlə/, in which the l occurred between vowels and did not vocalize)
By another sound change, the diphthongs resulting from L-vocalization were simplified to monophthongs:
- Modern French chaud [ʃo]
- Modern French beau [bo] (belle [bɛl])
Slavic languages 
- In Bulgarian, young people often pronounce the [L] of the standard language as [w] or [o], especially in an informal context. For example, pronunciations which could be transcribed as [maʊ̯ko] or [mao̯ko] occurs instead of standard [malko] ("a little").
- In Polish and Sorbian languages, all historical /ɫ/ have become /w/, even in word-initial and inter-vocalic position. For example, Polish ładny "pretty, nice" is pronounced [ˈwadnɨ]; słowo "word" is [ˈswɔvɔ]; and mały "small" in both Polish and Sorbian is [ˈmawɨ] (cf. Russian малый [ˈmaɫɨj]). The /w/ pronunciation dates back to the 16th century, first appearing among the lower classes. It was considered an uncultured accent until the mid-20th century when this stigma gradually began to fade. As of the early 2000s, /ɫ/ can still be used by some speakers of eastern Polish dialects, especially in Belarus and Lithuania.
- In Ukrainian, at the end of a closed syllable, historical /ɫ/ has become /w/. For example, the Ukrainian word for "wolf" is вовк /ʋowk/, cf. Russian вoлк [voɫk].
- In Serbo-Croatian, a historical /l/ in coda position has become /o/ and is now so spelled. For example, the Serbo-Croatian name of Belgrade is Beograd. However, in Croatian the process is partially reversed; compare Croatian stol, vol, sol vs. Serbian sto, vo, so (meaning "table", "ox" and "salt").
- In Slovene historical coda /l/ is still spelled as l but pronounced as /w/.
Uralic languages 
- In Hungarian, former palatal lateral *ʎ (still written by a separate grapheme ly) has become a semivowel /j/.
- Proto-Uralic *l was vocalized to *j in several positions early on in the history of the Samoyedic languages.
- Most Zyrian dialects of Komi vocalize syllable-final /l/ in various ways: this may result in [v], [u], or vowel length.
- Veps also vocalizes original syllable-final *l to /u/.
Vocalization to i or j 
- In Austro-Bavarian, the etymological /l/ is vocalised into i or y, e.g. vui corresponding with High German viel ("much"). The same phenomenon occurs in Missingsch, as well, but only when the etymological /l/ precedes a syllable-final velar consonant.
- In early Italian, /l/ vocalized between a preceding consonant and a following vowel to /j/, e.g. Latin flos > Italian fiore, Latin clavis > Italian chiave.
See also 
- Labov, William, Sharon Ash, and Charles Boberg. 2006. The Atlas of North American English. Berlin: Mouton de Gruyter. ISBN 3-11-016746-8.
- KM Petyt, Dialect & Accent in Industrial West Yorkshire, John Benjamins Publishing Company, page 219
- Asher, R.E., Simpson, J.M.Y. (1993). The Encyclopedia of Language and Linguistics. Pergamon. p. 4043. ISBN 978-0080359434
- Kortmann, Bernd et al. (2004). A Handbook of Varieties of English. Mouton de Gruyter. p. 196. ISBN 978-3110175325
- Wells, John C. (1982). Accents of English. Cambridge University Press. p. 259. ISBN 978-0521297196
- Harper, Douglas. "Bristol". Online Etymology Dictionary.
- L Hall-Lew & RL Starr, Beyond the 2nd generation: English use among Chinese Americans in the San Francisco Bay Area, English Today: The International Review of the English Language, Vol. 26, Issue 3, pp. 12-19. 
- Transcribing Estuary English, by J. C. Wells - discusses the phonetics of l-vocalization in Estuary English and Cockney.