Deformation of the hypopharyngeal cavities due to F-0 changes and its acoustic effects

A research was conducted to evaluate the effect of changes in fundamental frequency on the hypopharyngeal cavity shapes and acoustics during speech. The fall and rise of fundamental frequency during speech is often accompanied by vertical movements of larynx that deform the hypopharyngeal cavities and give rise to spectral changes in the high frequency region. The study reflected the geometrical changes of the hypopharyngeal cavities by altering spectral envelopes because the shape of the hypopharyngeal cavities remains stable across vowels at the comfortable level of fundamental frequency. MRI measurement obtained the volumetric images of hypopharyngeal cavities from an adult Japanese male speaker. The study has observed the effects of fundamental frequency as changes in the fourth formant and spectral dips between 4 to 5 KHz in recorded vowels. The changes were found to be consistent with the acoustic simulation based on MRI data.