Editing Great Vowel Shift (section)

===First phase===
The first phase of the Great Vowel Shift affected the Middle English close-mid vowels {{IPA|/eː oː/}}, as in ''beet'' and ''boot'', and the close vowels {{IPA|/iː uː/}}, as in ''bite'' and ''out''. The close-mid vowels {{IPA|/eː oː/}} became close {{IPA|/iː uː/}}, and the close vowels {{IPA|/iː uː/}} became diphthongs. The first phase was completed in 1500, meaning that by that time, words like ''beet'' and ''boot'' had lost their Middle English pronunciation and were pronounced with the same vowels as in Modern English. The words ''bite'' and ''out'' were pronounced with diphthongs, but not the same diphthongs as in Modern English.{{sfn|Lass|2000|pp=80–83}}
{| class="wikitable"
|+ First phase of the Great Vowel Shift
! rowspan="2" | Word !! colspan="2" | Vowel pronunciation
|-
! 1400 !! 1550
|-
! bite
| {{IPA|/iː/}} || {{IPA|/ɛi/}}
|-
! meet
| {{IPA|/eː/}} || {{IPA|/iː/}}
|-
! out
| {{IPA|/uː/}} || {{IPA|/ɔu/}}
|-
! boot
| {{IPA|/oː/}} || {{IPA|/uː/}}
|}

Scholars agree that the Middle English close vowels {{IPA|/iː uː/}} became diphthongs around 1500, but disagree about what diphthongs they changed to. According to Lass, the words ''bite'' and ''out'' after diphthongisation were pronounced as {{IPA|/beit/}} and {{IPA|/out/}}, similar to American English ''bait'' {{IPA|/beɪt/}} and ''oat'' {{IPA|/oʊt/}}. Later, the diphthongs {{IPA|/ei ou/}} shifted to {{IPA|/ɛi ɔu/}}, then {{IPA|/əi əu/}}, and finally to Modern English {{IPA|/aɪ aʊ/}}.{{sfn|Lass|2000|pp=80–83}} This sequence of events is supported by the testimony of [[orthoepy|orthoepists]] before Hodges<!-- Need to get a first name --> in 1644.

However, many scholars such as {{harvcoltxt|Dobson|1968}}, {{harvcoltxt|Kökeritz|1953}}, and {{harvcoltxt|Cercignani|1981}} argue for theoretical reasons that, contrary to what 16th-century witnesses report, the vowels {{IPA|/iː uː/}} were immediately centralised and lowered to {{IPA|/əi əu/}}.{{refn|group=nb|Centralizing to /ɨi ɨu/ and then lowering to /əi əu/ argued by Stockwell (1961).}}

Evidence from Northern English and Scots ([[#Northern English and Scots|see below]]) suggests that the close-mid vowels {{IPA|/eː oː/}} were the first to shift. As the Middle English vowels {{IPA|/eː oː/}} were raised towards {{IPA|/iː uː/}}, they forced the original Middle English {{IPA|/iː uː/}} out of place and caused them to become diphthongs {{IPA|/ei ou/}}. This type of sound change, in which one vowel's pronunciation shifts so that it is pronounced like a second vowel, and the second vowel is forced to change its pronunciation, is called a [[push chain]].{{sfn|Lass|2000|pp=74–77}}

However, according to professor [[Jürgen Handke]], for some time, there was a phonetic split between words with the vowel {{IPA|/iː/}} and the diphthong {{IPA|/əi/}}, in words where the Middle English {{IPA|/iː/}} shifted to the Modern English {{IPA|/aɪ/}}. For an example, ''high'' was pronounced with the vowel {{IPA|/iː/}}, and ''like'' and ''my'' were pronounced with the diphthong {{IPA|/əi/}}.<ref>{{cite web |url=https://www.youtube.com/watch?v=zyhZ8NQOZeo |title=PHY117 – The Great Vowel Shift |author=Jürgen Handke |date=Dec 7, 2012 |publisher=The Virtual Linguistics Campus |website=YouTube}}</ref> Therefore, for logical reasons, the close vowels {{IPA|/iː uː/}} could have diphthongised before the close-mid vowels {{IPA|/eː oː/}} raised.  Otherwise, ''high'' would probably rhyme with ''thee'' rather than ''my''. This type of chain is called a [[chain shift|drag chain]].