Measurement of sound and vibration at the lips, nostrils, and pharynx wall in speech utterance and simulation of sound leakage from the oral cavity to the nasal cavity in nonnasal sounds

Sounds and vibrations at the lips, the nostrils, and skin near the pharynx are measured separately in an anechoic room using a specially designed soundproof box with three microphones and three accelerometers. It is found that the radiation from the nostrils is not negligibly small even if the nonnasal sounds were spoken and that the nostril sound in a close vowel /i/ is stronger than that in an open vowel /a/. A buzz bar of voiced plosives is found to be radiated from both the nostrils and skin near the pharynx. Based on these findings, a vibrating plate model is introduced to simulate the acoustic coupling between the oral cavity and the nasal cavity through the velum. To simulate the radiation of the buzz bar of voiced plosives, an active inflation of volume of the pharynx cavity is introduced and the relationship between the inflation rate and the sound radiation is shown.