The Underlying Temporal Features in the Transition from Bouncing to Rolling Events

The organization of our representations within a multi-dimensional acoustic space provides information about the broad relationships and associations between common sound-events; however, less is known about sounds that have acoustic features that situate them between two typical events in feature space. In the present study, we examined the acoustic space of two simple event types: a bouncing event and a rolling event. Two continua of sound events, at different paces, were generated through a Delay-add procedure, whereby a natural recording of a rubber ball bouncing was added to itself to ultimately build up a series of closely-spaced, random, small impacts such as those commonly found in a rolling event. Listener ratings indicate that our continua of sounds perceptually transitions from bouncing to rolling events, and this transition occurs gradually. Second, we find that listeners are sensitive to the variability in the interval between impulses as well as the number of impulses present in the sound per unit time. Furthermore, we find that these two sound properties can unify the event categorization decisions across both continua, suggesting an important role for temporal features in the interpretation of sound events.