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 in Oman Stirrup flew BAC Strikemasters during the Dhofar War in the close air support and interdiction roles, giving him valuable battle experience of the use of air power in counter-insurgency operations. After he returned to Great Britain in 1975, Stirrup was posted to No. 41 Squadron where he flew the SEPECAT Jaguar in the fighter reconnaissance role. Stirrup went on to serve in an exchange tour in the United States where he flew the all-weather tactical reconnaissance RF-4C Phantom. Promoted to squadron leader on 1 January 1980, Stirrup was serving as a flight commander on No. 226 Operational Conversion