This article describes those aspects of the phonological history of English which concern consonants. The phonological history of English consonants involves major shifts from Old English to Modern English, characterized by cluster simplifications, palatalization, voicing changes, and loss of sounds. Influences from Old Norse and also from French introduced new sounds, while internal processes like assimilation and lenition streamlined the system, eventually creating the contemporary consonant inventory of English.

Consonant clusters

H-cluster reductions Reduction of /hw/ – to in a few words (such as who), but usually to , for the great majority of English speakers (so that whine comes to be pronounced the same as wine). Reduction of /hl/, /hr/ and /hn/, with the loss of the initial in Middle English. Reduction of /hj/ to in a few American and Irish dialects (so that hew is pronounced like yew).

Y-cluster reductions Yod-dropping – the elision of in certain clusters, depending on dialect (for example, RP has in new, while General American and Cockney do not). Yod-coalescence, whereby the clusters , , and become , , and respectively (for example, education is often pronounced as if it began "edge").

Other initial cluster reductions Reduction of /wr/ to , in words like wrap, around the 17th century (there was also a reduction of to in Middle English). Reduction of /kn/ and /ɡn/ to , in words like knot and gnome, around the 17th century. S-cluster reduction, in some types of Caribbean English, where for example spit is pronounced pit.

Final cluster reductions NG-coalescence – reduction of the final cluster to , in words like hang, which has occurred in all but a few English dialects. G-dropping – reduction of the final cluster to in weak syllables, principally in the verb ending -ing, which has occurred in many English dialects, although not in the modern standard varieties. Reduction of /mb/ and /mn/ to , in later Middle English, affecting words like lamb and column. Generalized final cluster reduction in African American Vernacular English (AAVE) and Caribbean English, where for example desk and hand may be pronounced "dess" and "han".

Other changes involving clusters Reduction of /ts/ to /s/ – a Middle English reduction that produced the modern sound of soft . Medial cluster reduction – elision of certain stops in medial clusters, such as the in postman. Insertion (epenthesis) of stops after nasals in certain clusters, for example making prince sound like prints, and dreamt rhyme with attempt. Assimilation of certain consonants in clusters, especially nasals. Glottalization and pre-glottalization (insertion of a glottal stop in place of or before a or other stop) in certain environments, depending on dialect. Certain other changes occurring in AAVE, including S-cluster metathesis (as with the use of "aks" for ask – an alternation which also has a long history in general forms of English), the merger of /str/ and /skr/, and yod-rhotacization (where beautiful is pronounced "brootiful").

Stops

Aspiration The voiceless stops , , are typically aspirated when they begin a stressed syllable, becoming , as described under English phonology (obstruents). There is some regional variation in the degree of aspiration, and in some Scottish and northern English accents aspiration does not occur at all.Wells (1982), p. 74.

In certain accents, such as Geordie (among younger women) and in some speakers of Dublin English, , and can be preaspirated when they come at the end of a word or utterance, becoming .

Flapping

Flapping, or tapping, is a process whereby or is pronounced as the alveolar flap in certain positions, especially between vowels (but also sometimes after other sonorants). It may be perceived as, for example, the pronunciation of butter as "budder". It occurs especially in North American English (to varying extents) and in Australian and New Zealand English.

Voicing Apart from the T-voicing that results from flapping (described above), some dialects feature other instances of voicing or lenition of the stops , and . In Geordie, these stops may be fully voiced (, , ) in intervocalic position. In Devon, stops and other obstruents may be voiced (or at least lenited) between vowels and when final after a weak vowel, so for example the and in jacket may approach the realizations and , making the word sound similar or identical to jagged.Wells (1982), pp. 343–344.

Glottalization Stops, chiefly the voiceless stops, and especially , are frequently glottalized or pre-glottalized in certain positions; that is, a stop may be replaced with the glottal stop , or else a glottal stop may be inserted before it. These phenomena are strongly dependent on the phonetic environment and on dialect. For details, see T-glottalization, as well as English phonology (obstruents) and glottalization in consonant clusters.

If all final voiceless stops are glottalized, as may occur in some London speech, then sets of words such as lick, lit and lip may become homophones, pronounced .Wells (1982), p. 323.

Fricatives and affricates

H-dropping and H-insertion

H-dropping is the omission of initial in words like house, heat and hangover. It is common in many dialects, especially in England, Wales, Australia and Jamaica, but is generally stigmatized, and is not a feature of the standard accents. The is nonetheless frequently dropped in all forms of English in the weak forms of function words like he, him, her, his, had and have. The opposite of H-dropping, called H-insertion or H-adding, may arise as a hypercorrection by typically H-dropping speakers, or as a spelling pronunciation.

Loss of velar and palatal fricatives The voiceless velar and palatal fricative sounds and , considered to be allophones of and reflected by the in the spelling of words such as night, taught and weight, were lost in later Middle English or in Early Modern English. Their loss was accompanied by certain changes in the previous vowels. In some cases became , as in laugh.

A is still heard in words of the above type in certain Scots and northern English traditional dialect speech. A is more commonly heard, especially in the Celtic countries but also for many speakers elsewhere, in the word loch and in certain proper names such as Buchan.

Alexander John Ellis reported use of [x] in England on the Yorkshire-Lancashire border and close to the Scottish border in the late nineteenth century.

For details of the above phenomena, see H-loss (Middle English). See also the vocalization of the voiced velar fricative .

Voiced/voiceless splits The Old English fricatives had voiceless and voiced allophones, the voiced forms occurring in certain environments, such as between vowels, and in words originating from the Kentish dialect (like vane, vinew, vixen, and zink), word-initially. In Early Middle English, partly by borrowings from French, they split into separate phonemes: . See Middle English phonology – Voiced fricatives.

Also in the Middle English period, the voiced affricate took on phonemic status. (In Old English, it is considered to have been an allophone of ). It occurred in Middle English not only in words like brigge ("bridge") in which it had been present in Old English but also in French loanwords like juge ("judge") and general.

After the Middle English period, a fourth voiced fricative, , developed as a phoneme (alongside the voiceless ). It arose from yod-coalescence () in words like measure, and from late French loanwords like rouge and beige.Prins, A.A., A History of English Phonemes, Leiden University Press 1972, p. 222.

Dental fricatives

As noted above, the Old English phoneme split into two phonemes in early Middle English: a voiceless dental fricative and a voiced dental fricative . Both continued to be spelt .

Certain English accents feature variant pronunciations of these sounds. These include fronting, where they merge with and (found in Cockney and some other dialects); stopping, where they approach and (as in some Irish speech); alveolarisation, where they become and (in some African varieties); and debuccalisation, where becomes before a vowel (found in some Scottish English).

Initial fricative voicing

Initial fricative voicing is a process that occurs in some traditional accents of the English West Country, where the fricatives , , and are voiced to , , and when they occur at the beginning of a word. (Words beginning , like three, develop instead.) In these accents, sing and farm are pronounced and . The phenomenon is well known as a stereotypical feature, but is now rare in actual speech.Wells (1982), p. 342. Some such pronunciations have spread from these dialects to become standard usage: the words vane, vat and vixen all had initial in Old English ().

A similar phenomenon occurred in both German and Dutch.

Homophonous pairs voiceless voiced IPA fail vale fail veil fairy vary fan van fast vast fat vat fault vault fear veer fecks vex fee vee feel veal feeler velar fend vend ferry very fetch vetch fetter vetter fest vest few view fie vie figure vigour file vial With vile-vial merger. file vile fill vill final vinyl fine vine fizz viz. focal vocal foist voiced folly volley foul vowel With vile-vial merger. fowl vowel With vile-vial merger. fox vox sag zag said zed sane Zane sap zap sax zax scene zine sea zee seal zeal see zee seen zine seine Zane seize zees sewn zone sing zing sink zinc Sioux zoo sip zip sit zit sone zone sown zone thigh thy thou (thousand(th)) thou (you) thrall drawl thread dread threw drew throne drone through drew thrown drone thrift drift thrive drive thriven driven throve drove

Other changes In Glasgow and some other urban Scottish accents, is given an apico-alveolar articulation, which auditorily gives an impression of a retracted pronunciation similar to .Cole, J., Hualde, J.I., Laboratory Phonology 9, Walter de Gruyter 2007, p. 69. Confusion between and (or ) occurs in some African varieties of English, so ship may be pronounced like sip (or chip).Wells (1982), p. 640. In Zulu English, it is reported that is sometimes replaced by .Wade, R., The structural characteristics of Zulu English, 4.2.3. The labiodental fricative is sometimes merged with the corresponding bilabial stop . Some speakers of Caribbean EnglishWells (1982), p. 568. and Mexican American English merge with , making ban and van homophones (pronounced as , or as with a bilabial fricative). The distinction of from is one of the last phonological distinctions commonly learnt by English-speaking children generally, and pairs like dribble/drivel may be pronounced similarly even by adults. In Indian English, is often pronounced like , sounded as or as a labiodental approximant .Wells (1982), p. 629. Some Indian speakers make various changes in the pronunciation of other fricatives: may become or ; may become or ; may become , or , may become or ; may become ; may become a bilabial or an aspirated stop .Wells (1982), pp. 628–629. For and , see th-stopping. For some speakers of Mexican American English, initial and may be used in place of each other, so jet may be pronounced as yet or vice versa."Chicano English", Universität Duisburg-Essen. Retrieved 2015-10-02. In Indian South African English, the typical realization of the labiodental fricatives are the approximants .

Approximants

Insertion and deletion of /j/ and /w/ In parts of the west and southwest of England, initial may be dropped in words like wool and woman; occasionally, though, a may be inserted before certain vowels, as in "wold" for old and "bwoiling" for boiling. Similarly, initial may be lost in words like yeast and yes (this has also been reported in parts of eastern England), and may be added in words like earth (making "yearth").Wakelin, M.F., Discovering English Dialects, Osprey Publishing 1994, p. 27.