Do nasalized fricatives exist?

Abstract

It has been claimed that nasalized fricatives, even sibilant fricatives, exist in some languages. To assess this claim we sought to discover how much velopharyngeal opening can be present before the acoustic and auditory characteristics of fricatives are affected. Two trained phoneticians produced steady-state voiced and voiceless strong and weak fricatives. The back pressure was intermittently bled with a tube of varying diameter (and thus impedance) inserted into the speaker’s mouth via the buccal sulcus and the gap behind the back molars, simulating nasal leakage. Intraoral pressure (Po) was sampled via a catheter inserted into the pharynx through the nose. The changes in amplitude and quality of frication were analyzed acoustically. We found that (1) a vent area of about 18 mm2 caused auditorily and acoustically noticeable lessening of fricative energy, e.g., sibilants sounded more like nonsibilants, (2) for a given vent aperture, Po was diminished less for voiceless than voiced fricatives (because the voiced fricatives have higher upstream impedance at the glottis) and consequently the same vent aperture impaired the amplitude and quality of frication of voiced fricatives more than voiceless ones. Thus the aerodynamic requirements for fricatives seem to be relatively narrow and unforgiving. [Research supported by Committee on Research, UCB, and by DGICYT, Spain, PB 96-1158.]