02554nas a2200193 4500008004100000245007500041210006900116520185900185653001702044653004502061653001202106653002902118653001102147653001302158100001702171700002602188700002602214856012002240 2011 eng d00aNo evidence for DPOAEs in the mechanical motion of the locust tympanum0 aNo evidence for DPOAEs in the mechanical motion of the locust ty3 a

Distortion-product otoacoustic emissions (DPOAEs) are present in non-linear hearing organs, and for low-intensity sounds are a by-product of active processes. In vertebrate ears they are considered to be due to hair cell amplification of sound in the cochlea; however, certain animals lacking a cochlea and hair cells are also reported to be capable of DPOAEs. In the Insecta, DPOAEs have been recorded from the locust auditory organ. However, the site of generation of these DPOAEs and the physiological mechanisms causing their presence in the locust ear are not yet understood, despite there being a number of potential places in the tympanal organ that could be capable of generating DPOAEs. This study aimed to record locust tympanal membrane vibration using a laser Doppler vibrometer in order to identify a distinct place of DPOAE generation on the membrane. Two species of locust were investigated over a range of frequencies and levels of acoustic stimulus, mirroring earlier acoustic recording studies; however, the current experiments were carried out in an open acoustic system. The laser measurements did not find any evidence of mechanical motion on the tympanal membrane related to the expected DPOAE frequencies. The results of the current study therefore could not confirm the presence of DPOAEs in the locust ear through the mechanics of the tympanal membrane. Experiments were also carried out to test how membrane behaviour altered when the animals were in a state of hypoxia, as this was previously found to decrease DPOAE magnitude, suggesting a metabolic sensitivity. However, hypoxia did not have any significant effect on the membrane mechanics. The location of the mechanical generation of DPOAEs in the locust’s ear, and
therefore the basis for the related physiological mechanisms, thus remains unknown.

10abioacoustics10adistortion-product otoacoustic emissions10ahearing10alaser Doppler vibrometry10alocust10atympanum1 aMoir, H., M.1 aJackson, Joseph, Curt1 aWindmill, James, F.C. uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.056465https://syndication.highwire.org/content/doi/10.1242/jeb.05646502023nas a2200193 4500008004100000245016200041210006900203260001600272300001100288490000600299520131800305100002401623700002201647700002601669700002601695700003301721700002301754856005201777 2014 eng d00aShrinking Wings for Ultrasonic Pitch Production: Hyperintense Ultra-Short-Wavelength Calls in a New Genus of Neotropical Katydids (Orthoptera: Tettigoniidae)0 aShrinking Wings for Ultrasonic Pitch Production Hyperintense Ult cMay-06-2014 ae987080 v93 a

This article reports the discovery of a new genus and three species of predaceous katydid (Insecta: Orthoptera) from Colombia and Ecuador in which males produce the highest frequency ultrasonic calling songs so far recorded from an arthropod. Male katydids sing by rubbing their wings together to attract distant females. Their song frequencies usually range from audio (5 kHz) to low ultrasonic (30 kHz). However, males of Supersonus spp. call females at 115 kHz, 125 kHz, and 150 kHz. Exceeding the human hearing range (50 Hz–20 kHz) by an order of magnitude, these insects also emit their ultrasound at unusually elevated sound pressure levels (SPL). In all three species these calls exceed 110 dB SPL rms re 20 m Pa (at 15 cm). Males of Supersonus spp. have unusually reduced forewings (,0.5 mm 2 ). Only the right wing radiates appreciable sound, the left bears the file and does not show a particular resonance. In contrast to most katydids, males of Supersonus spp. position and move their wings during sound production so that the concave aspect of the right wing, underlain by the insect dorsum, forms a contained cavity with sharp resonance. The observed high SPL at extreme carrier frequencies can be explained by wing anatomy, a resonant cavity with a membrane, and cuticle deformation.

1 aSarria-S, Fabio, A.1 aMorris, Glenn, K.1 aWindmill, James, F.C.1 aJackson, Joseph, Curt1 aMontealegre-Zapata, Fernando1 aEtges, William, J. uhttp://dx.plos.org/10.1371/journal.pone.0098708