Hearing in insects: The nature of the response of certain receptors to auditory stimuli

Abstract

The auditory receptors of the Orthoptera include tympanal organs and hair sensilla. The former have long been recognized as subserving an aural function, but the latter have, in this group, only recently been shown to respond to auditory stimuli (Pumphrey and Rawdon-Smith, 1936). Wever and Bray (1933), using an amplifier and telephones, have attempted to analyse the nervous response from the tympanal organs of the foreleg of crickets ( Lyogryllus campestris ). Their operational technique may be shortly described. Without previous dissection, a fine wire electrode was introduced into the leg of the experimental animal, the return lead consisting of a pad applied to the animal’s body. Owing to the fact that no direct contact was certainly made with the tympanal nerve and that the central ends of the leg nerves were not severed, responses of several kinds were obtained. Of these, an asynchronous response, described as producing a shushing noise in the telephones, was thought to arise from the tympanal organ; but no certain indication was given that this response was not partly or wholly of tactile origin. This point is of importance since, as we shall show in this paper, a response from certain types of tactile receptor may be readily elicited by an auditory stimulus. Similar criticisms apply to the recent results of Wever (1935) on the tympanic organ of the grasshopper (Arphea sulphurea).