The overall goal of the proposed research is to continue the investigation of hearing in complex environments in the budgerigar (Melopsittacus undulatus), a small Australian parrot, and to compare these results from small birds to those found in humans and other animals. Much is already known about hearing in the budgerigar, which makes them an excellent species to use in experiments on echo suppression. Although their sound localization capabilities are not remarkable, they exhibit a large amount of free-field binaural unmasking and it has recently been discovered that they have much better temporal resolution in fine structure discrimination tasks than humans. Here, operant conditioning and psychoacoustic methods will be used to measure echo suppression in budgerigars. In a series of experiments, two speakers with an azimuthal separation will each present a click. The sounds will be delayed by a set amount, and the delay will change with each experiment. The smallest amount of delay between the two clicks that the budgerigars still report as one click will be the precedence effect and summing localization measurements. The echo threshold is the delay between the two speakers at which the budgerigars report two distinct clicks. These experiments help us understand how these small birds deal with echoes in their complex natural environments.
