The phonological history of the English language includes various changes in the phonology of consonant clusters. H-cluster reductions The H-cluster reductions are various consonant reductions that have occurred in the history of English, involving consonant clusters beginning with that have lost the (or become reduced to ) in some or all dialects. Reductions of /hw/ The cluster (spelled ⟨wh⟩ since Middle English) has been subject to two kinds of reduction: Reduction to before rounded vowels (due to being perceived as a with the labialization characteristic of that environment). This occurred with the word how in the Old English period, and with who, whom and whose in Middle English (the latter words having had an unrounded vowel in Old English). Reduction to , a development that has affected the speech of the great majority of English speakers, causing them to pronounce ⟨wh-⟩ the same as ⟨w-⟩ (sometimes called the wine–whine merger or glide cluster reduction). The distinction is maintained, however, in Scotland, most of Ireland, and some Southern American English. Reduction of /hl/, /hr/ and /hn/ The Old English consonant clusters , and were reduced to , , and in Middle English. For example, Old English , and become loaf, ring and nut in Modern English. Reduction of /hj/ In some dialects of English the cluster is reduced to , leading to pronunciations like for huge and for human, and making hew a homophone of ewe and 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 of hew, human, etc. is often reduced from to just (a voiceless palatal fricative). Y-cluster reductions Y-cluster reductions are reductions of clusters ending with the palatal approximant , which is the sound of in yes, and is sometimes referred to as "yod", from the Hebrew letter yod(h), which has the sound . Many such clusters arose in dialects in which the falling diphthong (the product of the merger of several Middle English vowel sequences) became the rising diphthong . (For more information, see Phonological history of English high back vowels.) They were