Past experiments have also suggested that people can discern height from voice. The new analysis not only confirms this ability but also points to what may be clueing in listeners: the sound produced in the lower airway below the Adam's apple—or the lump of cartilage that protrudes from the larynx. (Explore an interactive of the human body.)

The idea, explained study leader John Morton, a psychologist at Washington University in St. Louis, is similar to what happens when you blow air through a bottle.

If the bottle is bigger and taller, the sound is more resonant than if the bottle were smaller and shorter. But unlike with bottles, people aren't simply picking out deeper voices as belonging to taller people,