Active echolocation is a sensory modality possessed by a variety of mammals and is used for the identification, classification and localization of objects. A multi stage model of the bat echolocation process has been used with recordings of rotated disks to plot frequency spectrums of the signals reaching each of the bats' ears. Recordings from objects made within the human audible frequency range have also been made for use in psychoacoustic experiments aimed at validating preliminary studies that have shown some human ability to localize objects using echolocation.