Linguis. modification of the sound of a morpheme in a given linguistic context (Ex.: the pronunciation of the in “the man” and in “the old man” or of am as ('m) in “I am glad”)
See sandhi in American Heritage Dictionary 4
(sănˈdē, sänˈ-)
noun
Modification of the sound of a word or morpheme when juxtaposed with another, especially in fluent speech, as the modification of the pronunciation of don't in don't you from its pronunciation in isolation or in a phrase like don't we.