do males use a pressure gradient receiver?
Males and females of Phaneropterides engage in acoustical duetting in order to find mates. The males produce a mating call, and females respond acoustically to the male call. Males then approach a female, guided by her response call. As males compete for females there is strong pressure on the males to efficiently approach females. Thus the hearing system of the males must be sensitive and allow the accurate localization of females. Sexual dimorphism of the ears has been observed in this group: the acoustic trachea, which brings the sound to the ear, is enlarged in males, resulting in a more sensitive ear. The structure of this trachea suggests that in males directional hearing may be improved; however no data are available on this problem. I plan to test the hypothesis that males have developed a hearing system that will help them localize the target sound more efficiently. To detect the direction of sound, animals use differences between the sounds reaching the two ears (binaural dir
