Cochlea to structures in the brainstem for further processing. The "stapes" (stirrup) ossicle bone of the middle ear transmits vibrations to the "fenestra ovalis" (oval window) on the outside of the cochlea, which vibrates the perilymph in the "vestibular duct" (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in
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.