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
Great Stirrup Controversy also been asserted that modern reenactment and experimental archaeology has shown that the stirrup provides very little benefit for a mounted lancer, and a cantled saddle and spurs have a greater effect. White noted the importance of the prior emergence of the saddle, but argued, "The stirrup made possible—although it did not demand—a vastly more effective mode of attack" (than a blow "delivered with the strength of shoulder and biceps"): "now the rider could lay his lance at rest, held between the upper arm and the body, and make at his foe, delivering the blow not with his muscles but