Obtaining acoustic similarity measures from animals: a method for species comparisons.

An efficient procedure has been developed for obtaining similarity measures for complex acoustic signals in small birds. Birds were trained using operant conditioning procedures to detect changes in the repeating background of an ongoing sound. Response latencies for detection were used to construct similarity matrices. Multidimensional scaling procedures were then used to produce spatial maps of these complex sounds reflecting perceptual organization. An example using contact calls from two avian species is described.