Noise at the glottis during speech production

Abstract

Turbulence in the airflow near the glottis can result in the generation of noise, usually called aspiration noise. This noise can occur with or without vocal fold vibration, and can exist in conjunction with other sources of noise at constrictions above the glottis. Based on theoretical considerations, together with experimental data from speech acoustics and from models, a method has been developed for estimating the level, spectrum, and location of the aspiration noise source from knowledge of the glottal opening and the airflow. Some uncertainties remain in predicting the level of the source because of individual differences in airway configuration. Calculations of the radiated sound pressure for breathy voicing, for aspirated consonants, and for sounds with supraglottal constriction lead to absolute levels and spectra that are consistent with measured data for utterances from several speakers. These theoretical analyses can be used to aid in the development of improved methods for the systhesis of speech and for the interpretation of acoustic data from speech. [Work supported in part by a grant from the National Institutes of Health.]