SUPRAGLOTTAL ACOUSTICS AND VOWEL INTRINSIC FUNDAMENTAL-FREQUENCY - AN EXPERIMENTAL-STUDY
Two excised human larynges were used to investigate the effects of changes in supraglottal acoustics on phonation, especially fundamental frequency (F0). An artificial supraglottal tube was connected to the larynx. Two different sized cylindrical blocks were inserted and moved in the tube to simulate the acoustics of neutral. front and back vowels. The changes in supraglottal acoustics were found to influence the vibratory pattern of the vocal folds from irregular to regular and also vice versa. Variations in F0 were also observed. The F0 changes were greatest at the instant when the blocks were inserted in the tube, i.e. when the tube was converted from open to blocked. Moving the block caused slight changes only. When the smaller block was inserted an F0 rise was generally noted. On average (X +/- SD) a 3.8 +/- 0.9 Hz F0 rise was measured in low chest phonation. F0 changes connected with the use of the larger block did not show any systematical variation. In many cases an F0 drop was measured. The results are interpreted in terms of an acoustic-mechanical feedback in vocal source-tract interaction. It is concluded that the so-called intrinsic F0 of vowels cannot be explained on an acoustical basis. The acoustical conditions for the small block were simulated using a theoretical model.
acoustics vowels phonation fundamental frequency larynx vocal folds pitch vocal tract