Instabilities in human voice - one piece of the puzzle solved

What is it about?

Sudden voice breaks between chest and falsetto registers are among the least understood phenomena occurring in human voice. They occur involuntarily during puberty, mainly in boys, or during highly emotional situations, but can also be explored artistically in some singing styles, like yodelling or country singing. In this paper we definitely prove that such jumps are due to inherent properties of our vocal folds. We used excised larynges („voice boxes“) with no vocal tract and phonated them with airflow. We eliminated acoustic interactions with surroundings by removing the vocal tract (cavities above vocal folds) and by using our recently constructed resonance-free trachea. When elongating the vocal folds smoothly, we observed sudden frequency jumps. The jumps occurred even when all the acoustic resonances were removed. Nevertheless, when present, the subglottal resonance slightly changed the initial and terminating frequencies of the jumps revealing that the vocal folds behave differently when interacting with subglottal acoustics.

Featured Image

Photo by Jason Rosewell on Unsplash

Photo by Jason Rosewell on Unsplash

Why is it important?

The results are important for understanding why our voices sometimes break. It reveals on the fundamental principles of voice production. The paper provides the first empirical evidence that acoustic resonators are not needed for jumps to occur. It specifically shows that • Abrupt frequency jumps in voice are nonlinear dynamic events – bifurcations • Frequency jumps keep occurring when acoustic resonances around larynx are removed • Acoustic resonances around larynx can modify frequency jump characteristics

Perspectives