Acoustic phonetic features in Athabaskan sound change

A number of consonant shifts in the history of Athabaskan languages are considered. The goal is to better explain examples of ‘auditorily based substitution’ by invoking ‘phonetic features’ as is required by the sound change theory of Blevins (2004). We argue that the shifts are better understood as instances of Blevins’s change process involving the phonetic features ⟦grave⟧ and ⟦flat⟧. These features are defined acoustically in accord with recent phonetic studies of obstruents. It is crucial that these and other phonetic features are scalar-valued, and thus are part of a phonetics-phonology interface component which is separate from the distinctive phonological feature system.