The stability of phonological features within and across segments
This paper argues that the articulatory-acoustic stability of phonological features may be affected not only by concurrent features, but also by features in adjacent segments which may coincide in time due to coarticulatory overlap. Specifically, the paper illustrates how frication may be endangered by concurrent and coarticulatory nasality. We review aerodynamic and acoustic evidence showing that fricatives tend to be impaired and become unstable with co-occurring nasalization. Then we examine the stability of fricatives when they come in contact with nasality in adjacent segments. An experiment is described where aerodynamic and acoustic data were obtained for fricative + nasal sequences at slow and fast rates. The results show that anticipatory velophrayngeal opening during the acoustic duration of the fricative vents the high oral pressure required for audible frication, thus providing support for the claim that the same physical principles disfavoring the combination of frication and nasality within a segment are at play when these features combine across segments. It is argued that the instability of frication when combined with nasalization may be at the origin of a number of phonological patterns.