Do–dew merger

The phonological history of the English language includes various changes in the phonology of consonant clusters.

The H-cluster reductions are various consonant reductions that have occurred in the history of English, involving consonant clusters beginning with /h/ that have lost the /h/ (or become reduced to /h/) in some or all dialects.

The cluster /hw/ (spelled ⟨wh⟩ since Middle English) has been subject to two kinds of reduction:

The Old English consonant clusters /hl/, /hr/ and /hn/ were reduced to /l/, /r/, and /n/ in Middle English. For example, Old English hlāf, hring and hnutu become loaf, ring and nut in Modern English.

In some dialects of English the cluster /hj/ is reduced to /j/, leading to pronunciations like /juːdʒ/ for huge and /ˈjuːmən/ for human, and making hew a homophone of ewe or you. This is sometimes considered a type of glide cluster reduction, but it is much less widespread than wh-reduction, and is generally stigmatized where it is found. Aside from accents with general H-dropping, in the United States this reduction is mostly found in accents of Philadelphia and New York City; it also occurs in Cork accents of Irish English. In other dialects of English hew and yew remain distinct; however, the cluster /hj/ of hew, human, etc. is often reduced from [çj] to just [ç] (a voiceless palatal fricative).

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