This paper presents results from a general study of nasal airflow for a speaker of English. Nasal flow was recorded for approximately 1000 tokens in a carrier phrase, along with the audio output. The results support a hierarchical arrangement of vowels according to manifestation of nasal flow (in nasal environments) which parallels their oral impedance. This is consistent with acoustical studies of the effects of nasal coupling, as well as some perceptual studies, but differs in crucial ways from previous articulatory work. Other contextual segmental effects are observed, including a striking attenuation of the flow curve in final voiceless clusters. A revised definition of nasality, based on aerodynamic criteria, is advanced. Based on this definition, the circumstances under which nasality “spreads” was investigated, along with the flow characteristics of different segments. [Work supported by NIH.]