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
History of beliefs about the human body is important to understanding histories of coercion and control, sex and gender, and other important but culturally varied aspects of human experience. Another prominent voice in the field at the same time was Caroline Walker Bynum, whose 1988 "Holy Feast and Holy Fast" became a landmark study. Both Bynum and Porter noted that during the 1980s Western history of the body research drew on post-structuralist thought, such as Michel Foucault's ideas of biopolitics and biopower, which emphasised that state power is not abstract, but exercised through and over human bodies. But both expressed a concern that research was focusing too