Perception of complex tones and its analogy to echo spectral analysis in the bat, Megaderma lyra

The gleaning bat Megaderma lyra emits broadband echolocation sounds consist ing of multiple frequency components. The present study investigates into w hich perceptual qualities the spectral characteristics of echoes may be tra nslated in the auditory system of M. lyra. Three bat!, were trained in a 2- AFC behavioral experiment to classify nine complex tones, which spectrally resembled M. lyra's sonar calls, into two perceptual categories. Then the b ats' spontaneous responses to unknown complex tones were recorded. The resu lts show that the animals based their classifications of the complex tones on a sound quality which was mediated by their broadband frequency spectra. The bats used the training stimuli as spectral templates and classified th e test stimuli according to their broadband spectral similarity with the le arned patterns. Assuming; that passive hearing and echo processing are gove rned by similar perceptual qualities and subject to similar limitations, th e perceptual mode which was used by the bats to compare the multicomponent spectral patterns in the reported experiments could serve as a powerful too l for the spectral analysis of M. lyra's multicomponent echoes. The analogy between the perception of complex tones and echo spectral analysis in M. l yra is theoretically elaborated in the "formant-mode" model. (C) 1999 Acous tical Society of America. [S0001-4966(99)04501-4].