A Study of Soprano Singing in Light of the Source-Filter Interaction
Abstract
We examined the physical interaction between the voice source system in the larynx and the acoustic filter of the vocal tract. The vocal tract of a soprano was first scanned in three dimensions using magnetic resonance imaging (MRI) while she produced four musical notes with different vowels. These images were used to simulate voice production, including the vibratory motion of the vocal folds and the behavior of glottal airflow. Images for the /i/ vowel were used in the simulation, because a good proximity relationship was found between the fundamental frequency and the first impedance peak of the vocal tract. The simulation results revealed that the fundamental frequency (vibration frequency of the vocal folds) was decreased to a large extent by the source-filter interaction especially when their natural frequency was in the proximity of the impedance peak. In a specific case, this frequency lowering had the effect of changing the acoustic load of the vocal tract exerted on the vocal folds so that their vibratory motion was effectively assisted.