Aerodynamic reduction in American English flapping

Abstract

Are all tongue tip gestures for /t,d/ the same? Acoustic and articulatory studies have revealed that /t,d’s show a gradient behavior, in which invariancy is nonexistent. These results undermine phonological rules which represent leniting processes, such as flapping, as a rule where /t,d/ is replaced by an invariant flap. Adding to more evidence for gradiency, an aerodynamic experiment was designed to investigate the nature of alveolar tongue tip gestures, specifically in flapping contexts. Three native speakers of American English were recruited and each yielded 200 tokens, which contained medial /t,d/ in different phonetic contexts (stressed-syllable onset, unstressed-syllable onset, n+/t,d/, l+/t,d/ and r+/t,d/) and in two speaking rates. For each target consonant, duration ratio and airflow rate were obtained. In general, both duration ratio and airflow rate showed gradiency across rate and context. Tokens at a normal speech rate yielded higher ratios and airflow rates than tokens at a faster speech rate. However, rate did not affect each context equally. Accordingly, /t,d’s reveal a gradient behavior which ranges from a canonical stop to complete deletion.