Cochlea a protein motor called prestin on their outer membranes; it generates additional movement that couples back to the fluid–membrane wave. This "active amplifier" is essential in the ear's ability to amplify weak sounds. The active amplifier also leads to the phenomenon of soundwave vibrations being emitted from the cochlea back into the ear canal through the middle ear (otoacoustic emissions). Otoacoustic emissions are due to a wave exiting the cochlea via the oval window, and propagating back through the middle ear to the eardrum, and out the ear canal, where it can be picked up by a microphone. Otoacoustic emissions
Jock Stirrup Unit which was based at RAF Lossiemouth in March 1983: his duties centred around the instruction of trainee pilots on the SEPECAT Jaguar and, on 7 March 1983, Stirrup was carrying out a student progress check from the rear seat of his aircraft when they suffered a serious bird strike. Stirrup was unable to ascertain whether his student was conscious and forward vision through the canopy was obscured: one of his engines caught fire, and although ejecting from the aircraft would have been justified, not knowing whether the student was conscious or not, Stirrup managed to land at RAF Leuchars.