South American cricket ears shown to rival human hearing

Scientists studying a species of South American bush cricket with some of the smallest ears known have discovered it has hearing so sophisticated that it rivals our own. The study is the first to identify hearing organs in an insect that are evolutionary convergent to those of mammals. The HFSP and BBSRC -funded research, led by the scientists at the University of Bristol, show how the bush cricket's ( Copiphora Gorgonensis ) auditory system has evolved over millions of years to develop auditory mechanisms strikingly similar to those of humans, but using an entirely different machinery. In mammals, hearing relies on three canonical processing stages: an eardrum collecting sound, a middle ear impedance converter and a cochlear frequency analyser. The bush cricket's ears, which are found on its two front legs, can perform all three stages, using ears that, despite being much smaller, work like those of humans, but look very different. After studying the bush cricket's microscopic auditory system the researchers discovered how impedance conversion - the process of efficiently converting air-borne sounds into liquid-borne vibrations - takes place in these insects. As a crucial stage of auditory processing in mammals, such process was unknown in insects and, in fact, was thought to only be an attribute of the ears of vertebrates.