02319nas a2200181   4500008004100000245008700041210006900128520167300197653002101870653001201891653001601903653001801919100001501937700002101952700001901973700002501992856012002017       2011                        eng d00aMatching sender and receiver: poikilothermy and frequency tuning in a tree cricket0 aMatching sender and receiver poikilothermy and frequency tuning 3 a<p>Animals communicate in non-ideal and noisy conditions. The primary method they use to improve communication efficiency is sender-receiver matching: the receiver&#39;s sensory mechanism filters the impinging signal based on the expected signal. In the context of acoustic communication in crickets, such a match is made in the frequency domain. The males broadcast a mate attraction signal, the calling song, in a narrow frequency band centred on the carrier frequency (CF), and the females are most sensitive to sound close to this frequency. In tree crickets, however, the CF changes with temperature. The mechanisms used by female tree crickets to accommodate this change in CF were investigated at the behavioural and biomechanical level. At the behavioural level, female tree crickets were broadly tuned and responded equally to CFs produced within the naturally occurring range of temperatures (18 to 27&deg;C). To allow such a broad response, however, the transduction mechanisms that convert sound into mechanical and then neural signals must also have a broad response. The tympana of the female tree crickets exhibited a frequency response that was even broader than suggested by the behaviour. Their tympana vibrate with equal amplitude to frequencies spanning nearly an order of magnitude. Such a flat frequency response is unusual in biological systems and cannot be modelled as a simple mechanical system. This feature of the tree cricket auditory system not only has interesting implications for mate choice and species isolation but may also prove exciting for bio-mimetic applications such as the design of miniature low frequency microphones.</p>
10afrequency tuning10ahearing10aOecanthinae10atree crickets1 aMhatre, N.1 aBhattacharya, M.1 aRobert, Daniel1 aBalakrishnan, Rohini  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.057612https://syndication.highwire.org/content/doi/10.1242/jeb.05761203077nas 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.078352