Aerodynamic characteristics of trills

What are the aerodynamic conditions required for trills? To find out we had two subjects produce steady‐state voiced, voiceless, and ejective alveolar trills. The backpressure during trills was intermittently bled with a tube of varying diameter (and thus impedance) inserted in the speaker’s mouth via the buccal sulcus and gap behind the back molars. Intraoral pressure was measured via a catheter inserted into the pharynx through the nose. The variation, impairment, or extinction of trilling as a function of gradual decrease in intraoral pressure was analyzed acoustically. It was found that (1) bleeding the oro‐pharyngeal pressure by 2 cm H₂O impaired sustained trilling; (2) the minimum Po required to sustain tongue‐tip vibration is lower than that required to initiate it; (3) extinction (and reinitiation) of trilling generally results in a fricative; (4) the range of Po variation for trills is narrower than that for fricatives; (5) voiceless and ejective trills are significantly less affected by venting the backpressure than voiced trills. The behavior of trills in varying aerodynamic conditions accounts for observed phonological patterns: final trill devoicing, alternation between trills and fricatives, co‐occurrence of trilling and frication, and limited distribution of trills. [Work supported by DGICYT, Spain, PB 96‐1158, and by Committee on Research, UCB.]