@article {58010, title = {A Tympanal Insect Ear Exploits a Critical Oscillator for Active Amplification and Tuning}, journal = {Current Biology}, volume = {23}, year = {2013}, month = {Jan-10-2013}, pages = {1952 - 1957}, abstract = {

A dominant theme of acoustic communication is the partitioning of acoustic space into exclusive, species-specific niches to enable efficient information transfer. In insects, acoustic niche partitioning is achieved through auditory frequency filtering, brought about by the mechanical properties of their ears [1]. The tuning of the antennal ears of mosquitoes [2] and flies [3], however, arises from active amplification, a process similar to that at work in the mammalian cochlea [4]. Yet, the presence of active amplification in the other type of insect ears\—tympanal ears\—has remained uncertain [5]. Here we demonstrate the presence of active amplification and adaptive tuning in the tympanal ear of a phylogenetically basal insect, a tree cricket. We also show that the tree cricket exploits critical oscillator-like mechanics, enabling high auditory sensitivity and tuning to conspecific songs. These findings imply that sophisticated auditory mechanisms may have appeared even earlier in the evolution of hearing and acoustic communication than currently appreciated. Our findings also raise the possibility that frequency discrimination and directional hearing in tympanal systems may rely on physiological nonlinearities, in addition to mechanical properties, effectively lifting some of the physical constraints placed on insects by their small size [6] and prompting an extensive reexamination of invertebrate audition.

}, issn = {09609822}, doi = {10.1016/j.cub.2013.08.028}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0960982213010348https://api.elsevier.com/content/article/PII:S0960982213010348?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0960982213010348?httpAccept=text/plain}, author = {Mhatre, Natasha and Daniel Robert} } @conference {57991, title = {Sound reception and radiation in a small insect}, booktitle = {Acoustics 2012}, year = {2012}, address = {Nantes, France}, abstract = {

Insects are small; this is a fact of their life. In some contexts this is an advantage, such as insects do not injure themselves through the effects of gravity. In other contexts this is a disadvantage, especially in the context of sound production and reception. The wavelengths of sound that insects such as crickets produce and receive are several times larger than their body size. For sound production, this is particularly challenging and inefficient, as sub-wavelength radiation (size to lambda ratio\ \>\ 1:100) requires great energy expenditure to produce sufficient sound pressure. In receiving sound, they face the reciprocal problem and are inefficient receivers. In addition,\  because of their size they cannot rely on cues other animals use to detect the direction of sound. Nonetheless, sound is extremely important to these insects as they use it for mate attraction and to evade predators. We investigate this problem by combining the technique of microscanning laser Doppler vibrometry with finite element modelling; and explain some of the biomechanical tricks a tiny tree cricket uses to overcome the disadvantages of size.

}, author = {Mhatre, Natasha and Montealegre-Z, Fernando and Rohini Balakrishnan and Daniel Robert} } @article {57948, title = {Energy localization and frequency analysis in the locust ear}, year = {2014}, abstract = {

Animal ears are exquisitely adapted to capture sound energy and perform signal analysis. Studying the ear of the locust, we show how frequency signal analysis can be performed solely by using the structural features of the tympanum. Incident sound waves generate mechanical vibrational waves that travel across the tympanum. These waves shoal in a tsunami- like fashion, resulting in energy localization that focuses vibrations onto the mechanosensory neurons in a frequency-dependent manner. Using finite element analysis, we demonstrate that two mechanical properties of the locust tympanum, distributed thickness and tension, are necessary and sufficient to generate frequency-dependent energy localization.

}, keywords = {energy localization, frequency discrimination, tension, travelling flexural wave, tympanum}, doi = {10.1098/rsif.2013.0857}, url = {https://royalsocietypublishing.org/doi/10.1098/rsif.2013.0857https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2013.0857}, author = {Malkin, Robert and McDonagh, Thomas R. and Mhatre, Natasha and Scott, Thomas S. and Daniel Robert} } @article {53366, title = {Tree cricket baffles are manufactured tools}, journal = {Ethology}, volume = {124}, year = {2018}, month = {Jan-09-2018}, pages = {691 - 693}, abstract = {

Tree crickets use sound to attract mates and make acoustic baffles to increase their sound production efficiency. It has been recently discovered that these insects use a flexible yet inherited behavioural programme to make acoustically optimal baffles. Whether these baffles qualify as tools, however, remains controversial. Here, baffle-using and baffle-making behaviours are analysed using the most current and authoritative definition of tool use. The current definition of tool use does not require the tool to be detached from the substrate and includes attached but manipulable external objects. Given this schema, tree cricket baffles, which are attached but manipulated prior to use, must be considered tools. The mode of manufacture for a baffle is \“Subtract,\” and the mode of use is \“Drape\”.

}, doi = {10.1111/eth.2018.124.issue-910.1111/eth.12773}, url = {http://doi.wiley.com/10.1111/eth.2018.124.issue-9}, author = {Mhatre, Natasha}, editor = {Bertram, S.} }