Importance of hyoid region in voice quality

Abstract

Speech is a combined form of phonation and articulation in human beings. Both phonation and articulation implies the acoustic formation, which is the result of mechanical and aerodynamic forces. The acoustic system as a tube analogy is shaped with constrictions and regularities, which represents the vowels in the phonetic system. The effects of the anatomic sites such as mouth, tongue, and pharynx have been well studied in acoustic science. However, the deeper structures in the hypopharynx below the hyoid constriction have not been well defined in the quality and the vowel production. This study aims to identify the effect of hyoid level and below on voice quality. 20 normal subjects, 7 females and 13 males are included in the present study. The mean age of the males is 30.8 and the mean age for females is 32.8. During data acquisitions, the subjects are instructed to produce Turkish phonetic vowels and the resulting sounds are recorded at a sampling rate of 44100 Hz. The recordings are repeated by applying backward pressure on the main corpus of the hyoid bone at its center. The data of pre and post constriction is analyzed by wide band spectrograms with a bandwidth of 100 Hz to obtain the formants F1-F4. The frequencies of the peak formantic levels which form the main data are compared using paired samples T-test. Although no significant changes were observed within the sex groups and the whole samples, voice changes are perceived by the listeners in all vocal tasks. As a conclusion, the hyoid region does have profound effect on the resonance system and thus on voice quality, but no considerable influence in the acoustic structure of vowels, i.e., articulation.|Keywords: Voice quality, hyoid, Turkish vowels, resonance, articulation