Mathematical Models and Electrophysiological Studies of Echolocation

Studies of cochlear microphonic potentials during landing maneuvers were conducted with special focus on the degree of Doppler shift encountered in real flights and the exact placement of output frequencies and Doppler shifted echoes in reference to the bats' sharply tuned ears. Data analyses are currently in progress. Theoretical analysis of bat sonars, in reference to CF as opposed to FM bats is continuing with publication of a paper on a model of wideband echolocation. Eighth nerve audiograms were conducted with the aid of chronically implanted electrodes. The audiograms proved to be greatly different from the cochlear microphonic audiogram in the same bats. The 'on' and the 'off' audiograms both showed tuning to the fundamental, second harmonic and third harmonic of the sonar pulses as well as to the elements of the FM sweeps and their harmonics but the tuning of the two curves is reciprocal. (Modified author abstract)