Auditory material perception

Two experiments are reported in which subjects identified the perceived material of synthetic impact sounds varying in two parameters: centre frequency and decay time. In one experiment, subjects were asked to write down the material they thought had produced the sound. The stimulus uncertainty was kept low, as the subjects could listen to a stimulus as often as they liked and listened to the sounds over headphones. In the other experiment, stimulus uncertainty was high, as subjects had to choose the material they thought produced the sound within three seconds after one stimulus presentation among five alternatives. In this forcedchoice condition, the five alternatives were the five materials most often mentioned on the response sheets in the first experiment. These were 'metal', 'wood', 'glass', 'rubber', and 'plastic'. It appears that the parameter values for which 'metal', 'wood', and 'glass' are perceived are similar for the two experimental conditions. For 'rubber' and even more so for 'plastic' the responses are more variable.