Articulatory dynamics of deaf speakers during plosive production: Aerodynamic and kinematic evidence

The production of speech requires precise movement and timing of the articulators to accurately valve the egressive airstream. While evident that deaf speakers often experience difficulty controlling such valves for speech production, the nature of such valving difficulties remains elusive. Previous aerodynamic studies have been primarily descriptive, characterizing steady-state aspects of speech production. The present study described and compared dynamic aspects of deaf and normal-hearing speakers' speech production using aerodynamic and kinematic measures. Five profoundly deaf and two normal-hearing young adults produced multiple tokens of voiced and voiceless plosive segments in varied vowel contexts, while simultaneous measures were obtained of oral and nasal airflow, oral pressure, and electroglottograph and acoustic signals. Conductance of oral and nasal vocal tract constrictions were used to describe and compare the magnitude and relative timing of articulatory gestures for deaf and hearing subjects. Computer simulation of the supraglottal air pressure and airflow waveforms was used to further investigate how these waveform variations may be related to articulatory maneuvers. Implications for speech training will be discussed. [Research supported by the Whitaker Foundation.]