03077nas a2200265   4500008004100000245012200041210006900163520220600232653001302438653001202451653002102463653002602484653001502510653001902525653001602544653001202560653001302572100001802585700001502603700001302618700001602631700002502647700001902672856012002691       2013                        eng d00aLow-pass filters and differential tympanal tuning in a paleotropical bushcricket with an unusually low frequency call0 aLowpass filters and differential tympanal tuning in a paleotropi3 a<p>Low-frequency sounds are advantageous for long-range acoustic signal transmission, but for small animals they constitute a challenge for signal detection and localization. The efficient detection of sound in insects is enhanced by mechanical resonance either in the tracheal or tympanal system before subsequent neuronal amplification. Making small structures resonant at low sound frequencies poses challenges for insects and has not been adequately studied. Similarly, detecting the direction of long-wavelength sound using interaural signal amplitude and/or phase differences is difficult for small animals. Pseudophylline bushcrickets predominantly call at high, often ultrasonic frequencies, but a few paleotropical species use lower frequencies. We investigated the mechanical frequency tuning of the tympana of one such species, Onomarchus uninotatus, a large bushcricket that produces a narrow bandwidth call at an unusually low carrier frequency of 3.2 kHz. Onomarchus uninotatus, like most bushcrickets, has two large tympanal membranes on each fore-tibia. We found that both these membranes vibrate like hinged flaps anchored at the dorsal wall and do not show higher modes of vibration in the frequency range investigated (1.5&ndash;20 kHz). The anterior tympanal membrane acts as a low-pass filter, attenuating sounds at frequencies above 3.5 kHz, in contrast to the high-pass filter characteristic of other bushcricket tympana. Responses to higher frequencies are partitioned to the posterior tympanal membrane, which shows maximal sensitivity at several broad frequency ranges, peaking at 3.1, 7.4 and 14.4 kHz. This partitioning between the two tympanal membranes constitutes an unusual feature of peripheral auditory processing in insects. The complex tracheal shape of O. uninotatus also deviates from the known tube or horn shapes associated with simple band-pass or high-pass amplification of tracheal input to the tympana. Interestingly, while the anterior tympanal membrane shows directional sensitivity at conspecific call frequencies, the posterior tympanal membrane is not directional at conspecific frequencies and instead shows directionality at higher frequencies.</p>
10aauditory10akatydid10alaser vibrometry10aOnomarchus uninotatus10aOrthoptera10apseudophylline10atettigoniid10atrachea10atympanum1 aRajaraman, K.1 aMhatre, N.1 aJain, M.1 aPostles, M.1 aBalakrishnan, Rohini1 aRobert, Daniel  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.078352https://syndication.highwire.org/content/doi/10.1242/jeb.07835200644nas a2200181   4500008004100000022001400041245006300055210006300118260002000181300001400201490000800215100003300223700001600256700002500272700001600297700001900313856013000332       2012                        eng d  a0036-807500aConvergent Evolution Between Insect and Mammalian Audition0 aConvergent Evolution Between Insect and Mammalian Audition  cApr-15-20122141  a968 - 9710 v3381 aMontealegre-Zapata, Fernando1 aJonsson, T.1 aRobson-Brown, K., A.1 aPostles, M.1 aRobert, Daniel  uhttp://www.sciencemag.org/cgi/doi/10.1126/science.1225271https://syndication.highwire.org/content/doi/10.1126/science.1225271