ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The ears of crickets (Teleogryllus commodus and an undescribed species) are sharply tuned to the frequency of the species' communication signal. The auditory tympanum is vibrated by sound simultaneously acting on its external surface and on its internal surface after entering the prothoracic tracheal system. The sensitivity and frequency of the hearing optimum of the ear ipsilateral to incident sound, however, does not depend on the interaction of the external and internal sound pressures at the tympanum. The tuned response of the ear does not depend on acoustic properties of the prothoracic leg trachea, but on unknown mechanisms at the ear itself. When considered in isolation from the rest of the auditory system, the cricket ear has no directional sensitivity to sound, in the range 2.0 kHz to 15.0 kHz, propagated in the plane perpendicular to the tibia. Directional sensitivity of the intact auditory system is achieved by a diminution of the response of the ear contralateral to the source. This is the result of sound transmission along the trachea from the ipsilateral ear to the contralateral tympanum, where destructive interference with the external sound pressure occurs. The directional sensitivity occurs in a narrow frequency band which includes the species' song frequency and it may depend in part on tuned transmission of sound in the trachea. The nature of the binaural response in crickets locomoting in a sound field is discussed in terms of the mechanism of directional hearing. The possible generality of this principle of directionality to other families of insects is considered.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00614182
