01910nas a2200181   4500008004100000245007300041210006900114520135500183653001001538653001101548653002901559653001101588653001301599100002001612700002101632700002001653856005501673       2014                        eng d00aMechanical basis of otoacoustic emissions in tympanal hearing organs0 aMechanical basis of otoacoustic emissions in tympanal hearing or3 a<p>Tympanal hearing organs of insects emit dis- tortion&ndash;product otoacoustic emissions (DPOAes), which in mammals are used as indicator for nonlinear cochlear amplification, and which are highly vulnerable to manipu- lations interfering with the animal&rsquo;s physiological state. Although in previous studies, evidence was provided for the involvement of auditory mechanoreceptors, the source of DPOAe generation and possible active mechanisms in tympanal organs remained unknown. Using laser Dop- pler vibrometry in the locust ear, we show that DPOAes mechanically emerge at the tympanum region where the auditory mechanoreceptors are attached. Those emission- coupled vibrations differed remarkably from tympanum waves evoked by external pure tones of the same frequency, in terms of wave propagation, energy distribution, and loca- tion of amplitude maxima. Selective inactivation of the auditory receptor cells by mechanical lesions did not affect the tympanum&rsquo;s response to external pure tones, but abol- ished the emission&rsquo;s displacement amplitude peak. These findings provide evidence that tympanal auditory recep- tors, comparable to the situation in mammals, comprise the required nonlinear response characteristics, which during two-tone stimulation lead to additional, highly localized deflections of the tympanum.</p>
10aDPOAE10aInsect10alaser Doppler vibrometry10alocust10atympanum1 aMöckel, Doreen1 aNowotny, Manuela1 aKössl, Manfred  uhttp://link.springer.com/10.1007/s00359-014-0914-2