Echolocating bats emit a highly directional sonar sound beam in the field by Annemarie Surlykke, Simon Boel Pedersen, and Lasse Jakobsen Proceedings B Volume 276(1658): March 7, 2009 ©2009 by The Royal Society

(a) The set-up with a linear horizontal array of three microphones and one microphone above the middle microphone. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society

(a,b) Isolation of first harmonic. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society

Removing interference from water reflections. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society

Flight path, beam direction and spectra. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society

Echolocation beam shape depends on frequency. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society

(a) Individual calls compared to average beam shape. Annemarie Surlykke et al. Proc. R. Soc. B 2009;276: ©2009 by The Royal Society