Editing Middle Dutch (section)

===Differences with Old Dutch===
Several phonological changes occurred leading up to the Middle Dutch period.

* Earlier Old Dutch {{IPA|/ie/}}, {{IPA|/ia/}}, {{IPA|/io/}} merge into {{IPA|/iə/}} already in Old Dutch.
* Voiceless fricatives become voiced syllable-initially: {{IPA|/s/}} > {{IPA|/z/}}, {{IPA|/f/}} > {{IPA|/v/}} (merging with {{IPA|/v/}} from Proto-Germanic {{IPA|/b/}}), {{IPA|/θ/}} > {{IPA|/ð/}}. (10th or 11th century)
* {{IPA|/ft/}} > {{IPA|/xt/}}
* {{IPA|/iu/}} > {{IPA|/yː/}} or {{IPA|/iə/}}. The outcome is dialect-specific, with {{IPA|/iə/}} found in more western dialects and {{IPA|/yː/}} further east. This results in later pairs such as ''dietsc'' {{IPA|/diətsk/}} versus ''duitsc'' {{IPA|/dyːtsk/}}.
** Various dialects also show {{IPA|/iw/}} > {{IPA|/yw/}}, while others retain {{IPA|/iw/}}. Compare southeastern Middle Dutch ''hiwen'' {{IPA|/hiwən/}} with modern Dutch ''huwen'' {{IPA|/ɦyʋə(n)/}}.
** In word-initial position, some northern dialects also show a change from a falling to a rising diphthong ({{IPA|/iu/}} > {{IPA|/juː/}}) like [[Old Frisian]]. Cf. the accusative second-person plural pronoun ''iu'' {{IPA|/iu/}} > northern ''jou'' {{IPA|/jɔu/}} versus southern ''u'' {{IPA|/yː/}}.
* Phonemisation of [[Germanic umlaut|umlaut]] for back vowels, resulting in a new phoneme {{IPA|/y/}} (from earlier Old Dutch {{IPA|/u/}} before {{IPA|/i/}} or {{IPA|/j/}}). Unlike most other Germanic languages, umlaut was only phonemicised for short vowels in all but the easternmost areas; long vowels and diphthongs are unaffected.
* Insertion of {{IPA|/w/}} between {{IPA|/uː/}} and a vowel.
* Syllable-final {{IPA|/uː(w)/}} > {{IPA|/ouw/}} in some areas. This created pairs such as ''duwen'' {{IPA|/dywən/}} versus ''douwen'' {{IPA|/dou(w)ən/}}, or ''nu'' {{IPA|/ny/}} versus ''nou'' {{IPA|/nou/}}.
* Lowering of {{IPA|/u/}} > {{IPA|/o/}} when not umlauted.
** This change did not (fully) occur in the southwestern (Flemish) dialects. Hence, these dialects retain ''sunne'' "sun" where others have ''sonne''.
* Fronting of {{IPA|/u/}}, {{IPA|/uː/}} > {{IPA|/y/}}, {{IPA|/yː/}}. In some dialects, {{IPA|/uː/}} remained syllable-finally or before {{IPA|/w/}}.
** This change did not occur in Limburgish.
** In Flemish, this change also affected cases that escaped the lowering in the previous change, hence ''sunne'' {{IPA|/ˈzynnə/}}.
* Vowel reduction: Vowels in unstressed syllables are weakened and merge into {{IPA|/ə/}}, spelled {{angbr|e}}. (11th or 12th century) Long vowels seem to have remained as such, at least {{IPA|/iː/}} is known to have remained in certain suffixes (such as ''-kijn'' {{IPA|/kiːn/}}).
* Diphthongisation of the long mid vowels: {{IPA|/eː/}}, {{IPA|/øː/}} {{IPA|/oː/}} > {{IPA|/eɛ/}}, {{IPA|/øœ/}}, {{IPA|/oɔ/}}.
* Non-phonemic lowering of short {{IPA|/i/}}, {{IPA|/y/}} > {{IPA|/ɪ/}}, {{IPA|/ʏ/}}.
* [[Open syllable lengthening]]: Short vowels in stressed open syllables become long. As a result, all stressed syllables in polysyllabic words become [[Syllable weight|heavy]]. Old Dutch (original) long vowels are called "sharp-long" and indicated with a circumflex (â, ê, î, ô). Lengthened vowels are "soft-long" and are indicated with a macron (ā, ē, ī, ō).
** Lengthened vowels initially have the same vowel quality as the short variants, so this produces {{IPA|[aː]}}, {{IPA|[eː]}}, {{IPA|[ɪː]}}, {{IPA|[oː]}}, {{IPA|[ʏː]}}.
** {{IPA|[ɪː]}} and {{IPA|[ʏː]}} are then lowered to {{IPA|[eː]}} and {{IPA|[øː]}} respectively.
** Lengthened {{IPA|[eː]}}, {{IPA|[øː]}}, {{IPA|[oː]}} remain distinct from the previously diphthongised long mid vowels.
** In most dialects, lengthened {{IPA|[aː]}} merges with original {{IPA|/aː/}}, but in some, a distinction in backness develops.
** This introduces many length alternations in grammatical paradigms, e.g. singular ''dag'' {{IPA|/dax/}}, plural {{lang|enm|dag(h)e}} {{IPA|/daːɣə/}}.
* Dental fricatives become stops: {{IPA|/ð/}} > {{IPA|/d/}}, {{IPA|/θ/}} > {{IPA|/t/}}, merging with existing {{IPA|/t/}} and {{IPA|/d/}}. (around 12th century)
** The geminate {{IPA|/θθ/}} (originating from Germanic ''*-þj-'') develops into {{IPA|/ss/}}: {{lang|odt|*withtha}} > {{lang|dum|wisse}}, {{lang|odt|*smiththa}} > {{lang|dum|smisse}}.
* [[L-vocalisation]]: {{IPA|/ol/}} and {{IPA|/al/}} > {{IPA|/ou/}} before dentals.
** This change does not occur in Limburgish, which retains the distinction but undergoes its own round of vocalisation in modern times, producing {{IPA|/ow/}} and {{IPA|/aː/}} respectively.
* Lengthening of vowels before {{IPA|/r/}} + dental consonant. This did not occur in all dialects, and in some, {{IPA|/e/}} was lengthened to {{IPA|/aː/}}. E.g. ''farth'' {{IPA|/farθ/}} > ''vāert'' {{IPA|/vaːrt/}}, ''ertha'' {{IPA|/erθa/}} > ''āerde'' {{IPA|/aːrdə/}}, ''wort'' {{IPA|/wort/}} > ''wōort'' {{IPA|/woːrt/}}.
* Syncope of schwa {{IPA|/ə/}} in certain environments, particularly inflectional endings. This phonemicises the soft-long vowels produced by open syllable lengthening, which can now also occur in closed syllables. E.g. ''hēvet'' > ''hēeft''.