Listen to the shapes

Scientists have long suspected that vibrations emanating from, say, the surface of a drum contain meaningful acoustic clues to its circular shape. A new study finds that individuals can indeed distinguish whether a vibrating plate hidden from view is circular, rectangular, or triangular.

“The shapes of thin, vibrating plates can be heard,” conclude Andrew J. Kunkler-Peck of Brandeis University in Waltham, Mass., and Michael T. Turvey of the University of Connecticut in Storrs. The researchers say they plan to explore how specific sound frequencies influence auditory-shape perception.

In one experiment, eight volunteers gave relatively accurate estimates of the heights and widths of three hidden, rectangular steel plates. The plates were suspended behind a screen and struck by a pendulum controlled by each listener. Using the same apparatus, another eight participants discerned the dimensions of vibrating steel, wood, and Plexiglas plates.

In further trials, volunteers successfully identified as circular, rectangular, or triangular each of a series of plates from these materials. Kunkler-Peck and Turvey’s work appears in the February Journal of Experimental Psychology: Human Perception and Performance.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.