Human sensitivity to acoustic information from vessel filling

A cylindrical vessel's fundamental resonant frequency increases as it fills with water. In Experiment 1, observers reliably identified water level rising, falling, or not changing. In Experiment 2, observers controlled filling well using only auditory information but less well than with multimodal information. Observers controlled fills to the brim better than to a drinking level, implying anticipation of fullness. In Experiment 3, blind and blindfolded sighted observers filled vessels to the brim using only auditory information. Fills tracked vessel height and flow rate well (R = .93, blind; R = .86, sighted). Experiment 4 tested sensitivity to acoustic time-to-full (TTF), analogous to optical tau. Estimated TTF to 3 fill levels at 3 rates tracked actual TTF (group R > .9; individual median R = .82). Results supported ecological perceptual theory: Changing acoustic information affords adaptive, prospective control of vessel filling.