French Phonological processes The following sections describe the major phonological processes occurring between written Late West Saxon (the standard written form of Old English) and the end of Middle English, conventionally dated to around 1500 AD. Homorganic lengthening Late in Old English, vowels were lengthened before certain clusters: , , , , . Later on, the vowels in many of these words were shortened again, giving the appearance that no lengthening happened; but evidence from the Ormulum indicates otherwise. For details see Phonological history of Old English: Vowel lengthening. Stressed vowel changes Late West Saxon (the standard written form of Old English) included matched pairs of short and long vowels, including seven pairs of pure vowels (monophthongs), , and two pairs of height-harmonic diphthongs, and . Two additional pairs of diphthongs, and , existed in earlier Old English but had been reduced to and , respectively, by late Old English times. In the transition to Middle English, this system underwent major changes, eliminating the diphthongs and leaving only one pair of low vowels, but with a vowel distinction appearing in the long mid vowels: The diphthongs simplified to and , respectively. Subsequently, the low vowels were modified as follows: and merged to a single central vowel . and rose to and , respectively. The diphthongs and (as in OE frēond 'friend') respectively simplified to new front-round vowels and (yielding /frøːnd/ 'friend'). Everywhere except in the southwest, and were soon respectively unrounded to and (yielding Middle English freend /freːnd/ 'friend'); in the southwest, it took 200 or 300 years for this process to take place, and in the meantime the sounds were spelled in texts from the southwest. The front-rounded vowels and unrounded to and , respectively, everywhere but in the southwest (former West Saxon area) and southeast (former Kentish area). In the southwest, the front-rounded vowels and remained, and were spelled . In the southeast, the vowels had already been unrounded to and , respectively, in Old English times, and remained as such in Middle English. This left an asymmetric system consisting of five short vowels and six long vowels , with additional front-rounded vowels in the southwest area. Some symmetry was restored by open syllable lengthening, which restored a long low vowel . Reduction and loss of unstressed vowels Unstressed vowels were gradually confused in late Old English, although the spelling lagged behind, due to the existence of a