15th International Congress of Phonetic Sciences (ICPhS-15)
Processes traditionally described as assimilations fall into two main types according to the impact they have on the informational content of speech signals. In grammar-internal assimilation, exemplified by vowel harmony, sound properties that are suprasegmentally extended have a linguistic marking function. In grammar-external assimilation, exemplified by lenition, the extended properties belong to the carrier signal.
Bibliographic reference. Harris, John (2003): "Grammar-internal and grammar-external assimilation", In ICPhS-15, 281-284.