By solving a bush-cricket mystery, researchers believe we could be closer to developing ultra-powerful microphones for surveillance.
One of the peculiarities of bush-crickets’ ear canals has been solved by an international team of sensory biologists and mathematicians. Writing in Biophysical Journal, the team said it discovered that the creature’s ear canals have evolved to work in the same way as mammals’ ears to amplify sound and modulate sound pressure.
This discovery, researchers added, could revolutionise how auditory devices identify the location or origin of a detected sound, paving the way towards ultra-powerful spy microphones or wireless acoustic sensor networks.
Bush-crickets depend on acoustic communication to survive, with the males singing to attract distant females. With very small ‘ears’ in their forelegs – similar in function to a human’s outer, middle and inner ear – and transparent ‘skins’, scientists can measure their ear processes.
As part of this latest research, the team found that the insects’ horn-shaped outer ear, called the acoustic trachea tube, captures sound in the same way as mammals’ ear canals by amplifying and transforming the pressure waves. These waves are then passed on to the surface of the eardrum, which gives the creature directional hearing.
Until now, how bush-crickets have been able to do this was a mystery. It was discovered with a combination of 3D x-ray imaging and mathematical analysis using a species called Copiphora gorgonensis, which is found in the rainforests of Colombia.
Dr Emine Celiker, a research fellow in numerical modelling in the School of Life Sciences at the University of Lincoln, conducted the study.
She said of the findings: “The research is the first step in using combined experimental and mathematical techniques to determine the mechanism crickets use to hear their species’ songs.
“Traditionally it is well known that horns increase the volume of sound, and for bush-cricket hearing it has been suspected that this is also the case due to the geometry of its acoustic tube.
“We verified this after a thorough investigation of the processes involved in the sound amplification. The findings have huge potential to be applied in enhancing acoustic sensors such listening devices.”