In Middle English, consonants and vowels altered values, and new phonemes appeared. Particularly, the distinction between the /f/ and /v/ consonants began to differentiate words (i.e. grief compared to grieve) and /s/ and /z/ (i.e. seal compared to zeal). The "ng" sound at the end of the word became contrastive (Old English "g" was always sounded). In the end, all vowels changed and the sound's spelling was altered (mainly due to French conventions). 

Middle English Changes to Pronunciation System

Affixes (prefixes and suffixes) saw a huge increase in Middle English. "Excluding inflectional endings, there are just over 100 prefixes and suffixes available for use in everyday English." In Middle English, an increase occurred with affixed words, including French introductions in Latin derived prefixes, for instance, 'con-' and 'de-'

Increase of Affixes

Old English contained variations in its word endings and Modern English rarely uses word endings. These inflections faded in the Middle English period as there was more reliance on alternative means of expression. Modern English focuses on word order and prepositional constructions to express meaning relationships. Progressive forms of the verb (i.e. I am going) and a range of auxiliary verbs (i.e. I have seen) became more prominent. Possession also appeared in this time and the use of the word "of."

Arizona State University

Middle English existed from around 1150 CE to 1450. It is noted as a language of transition between two eras (Old and Modern English). This period develops a language that displays a different structure from Old English, with changes, deriving from the influence of the French following the Norman Conquest of 1066.

Middle English 

Crystal, D. (2018, January 31). Middle English. British Library. Retrieved April 30, 2022, from https://www.bl.uk/medieval-literature/articles/middle-english 

Middle English Reference

The transition from Old English to Middle English is usually credited to the linguistic changes taking place and that Old English lost most of its inflectional endings, and word order to become the primary means of expression. However, there is continuity between the grammatical systems of Old and Middle English. Word order was different though by no means fixed even by Middle English as Old English inverted word order, placing the object initially.

Old to Middle English Transition 

Grammatical Change in Middle English

The French influence on English comes from the dominance of French power in England and French cultural influences in Europe, including law, architecture, estate management, music, and literature. Particularly, vocabulary was impacted. In the end,  about 30% of English vocabulary became French in origin.

French Influence on Middle English

During the shift to early modern English, the dialect was replaced by a more standardized language with an established lexicon and literature.

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