In contrast to the traditional treatment of Frisian vowel quantity as phonologically relevant, it is considered to be predictable and dependent on the type of contact (long vowel = open contact vs short vowel = close contact). The replacement of an open contact by a close one in Frisian started in the late 17th c. and has been going on until now. Most disyllabic words in Frisian as well as in the other Germanic languages consist of a root and a suffix. As a result of the change of the contact type (open > close) and, consequently, vowel shortening, the number of words with coinciding syllable and morpheme boundaries has increased. This is similar to the change that has taken place in English and Danish, but in Frisian it has some peculiarities, such as vowel shortening in disyllabic words with suffixes and a new Frisian breaking (the development of short rising diphthongs in close contact words from long falling diphthongs in open contact words). These peculiarities distinguish Frisian from the other West Germanic languages but they are typical of the Jutlandic Danish dialects where the new breaking occurs in the same types of words. In this process, short rising diphthongs, the result of the Old Frisian and Old Scandinavian breaking, may have served as a model in the formation of the new short rising diphthongs in Frisian and Jutlandic Danish. In this context, this change may have been a consequence of language contact. The replacement of close contact by open contact in disyllabic words in the language of the younger Frisian generation can be accounted for by the influence of Dutch, Low- and High German (the Frisian youngsters even in the Netherlands not to mention Germany having a better command in these languages than in Frisian). This development shows that the dominating process (open > close contact) in the Germanic languages, which could be caused by the effect of the self-adjusting language system ensuring a better segmentation of the root morpheme in text, can be violated by a language contact.