Sweep-Tone Measurements of Vocal-Tract Characteristics

The vocal tract was excited transcutaneously at a point just above the glottis by an external sweep-tone signal, in order to measure its transfer characteristics acoustically as continuous frequency functions. An analysis-by-synthesis procedure derived reliable data of vowels, in particular of the formant bandwidths, for three male and three female normal subjects. It has been shown for the closed glottis condition that the first formant bandwidths are higher for close vowels (typically 70 Hz for male subjects) than for semi-open vowels (typically 35 Hz for male subjects). Stationary consonantal articulations including stops, nasals, and nasalized vowels also have been studied, as well as the effect of opening the glottis on the vocal-tract transfer characteristics. The stop articulations give rise to a first-formant frequency slightly below 200 Hz. This fact and the high dissipation of the first formant is explained by assuming nonrigidness of the surrounding wall. Characteristics of nasalized vowels and nasal murmurs are also discussed based on the data obtained in this experiment.