Учебное пособие: The history of English

The velar consonants [k, g, x, y ] were palatalised before a front vowel, and sometimes also after a front vowel, unless followed by a back vowel. Thus in OE cild (NE child) the velar consonant [k] was softened to [k'] as it stood before the front vowel [i]: [*kild]>[k'ild]; similarly [k] became [k'] in OE spræc (NE speech) after a front vowel but not in OE sprecan ("NE speak) where [k] was followed by the back vowel [a]. In the absence of these phonetic conditions the consonants did not change, with the result that lingual consonants split into two sets, palatal and velar. The difference between them became phonemic when, a short time later, velar and palatal consonants began to occur in similar phonetic conditions; cf. OE cild [k'ild], ciest [k'iest] (NE child, chest) with palatal [k'] and ceald, cepan (NE cold, keep) with hard, velar [k] — both before front vowels.

Though the difference between velar and palatal consonants was not shown in the spellings of the OE period, the two sets were undoubtedly differentiated since a very early date. In the course of time the phonetic difference between them grew and towards the end of the period the palatal consonants developed into sibilants and affricates: [k']>[tſ], [g']>[dz]; in ME texts they were indicated by means of special digraphs and letter sequences.

The date of the palatalisation can be fixed with considerable precision in relation to other Early OE sound changes. It must have taken place after the appearance of [æ, æ:] (referred to the 5th c.) but prior to palatal mutation (late 6th or 7th c.); for [æ, æ:] could bring about the palatal