Randy Hurd – randyhurd@weber.edu
Weber State University
Department of Mechanical Engineering
Ogden, UT 84408
United States
Additional author: John Allen
Popular version of 5aMU3 – Acoustics of the Vanuatu Water Music
Presented at the 189th ASA Meeting
Read the abstract at https://eppro02.ativ.me//web/index.php?page=Session&project=ASAASJ25&id=3981726
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
Women in the island nation of Vanuatu create music in a unique way. Standing waist deep in a pool, they strike the water with their hands creating a unique variety of tones (see Figure 1). While the acoustics of inanimate objects entering water (such as spheres and raindrops) have long been understood, the mechanisms governing human hand strikes have received less attention. For this study, we replicate and simplify these musical techniques in a controlled laboratory environment to analyze the physical properties—the hydrodynamics and the resulting acoustic profile—of the sounds produced.
Figure 1: Women from the Leweton Cultural Group in the Banks Islands of Vanuatu dance together while interacting with the water surface to create music. (Image courtesy of The Secrets of Vanuatu Water Music. Directed by Marc Hoeferlin, ARTE France and ZED, 2015)
To isolate and measure these effects, we recreated the water-slapping motions in a transparent water tank. We used a high-speed camera to capture the subsurface cavity formation in detail (see figure 2), and recorded the sounds with both an in-air microphone and an underwater hydrophone.
Figure 2: A series of high-speed image sequences portray simplifications of four different techniques used by the women of Vanuatu to create music. a) A flat-handed slap produces a wide and shallow entrained air cavity. b) A cup-handed slap produces a slightly deeper cavity. c) A plunge with a deep hand produces a deep cavity that collapses in the final image. d) A horizontal plowing motion entrains air behind the hand (50 ms between images).
Figure 2: A series of high-speed image sequences portray simplifications of four different techniques used by the women of Vanuatu to create music. a) A flat-handed slap produces a wide and shallow entrained air cavity. b) A cup-handed slap produces a slightly deeper cavity. c) A plunge with a deep hand produces a deep cavity that collapses in the final image. d) A horizontal plowing motion entrains air behind the hand (50 ms between images).The key finding of this work is the establishment of a direct link between the physical motion of the hand, the shape and size of the air cavity created, and the acoustic characteristics of the sound produced. We find that the way the hand interacts with the water creates different subsurface cavities and control the volume and tone of the sound produced. Even hand-shape upon impact is shown to affect the resulting tone. In essence, the research demonstrates that the tone and duration of the sound are primarily controlled by the size and shape of the entrained air cavity. The larger the cavity, the deeper and longer the resulting sound.
The women of Vanuatu are incredibly sophisticated in their approach to creating music. They manipulate the sound spectrum without needing different instruments, simply by varying parameters like hand pose, curvature, and depth of penetration. This is a powerful demonstration of how multiphase flow, water entry and acoustics can produce an enriching and aesthetically complex experience.