The Science of Sound and Language

From Gavin Francis, at the New York Review of Books, "The Mysterious World of the Deaf":

The origins of our inner ear lie hundreds of millions of years back in evolution, when primitive fish began to develop hollows in the skin that were sensitive to waves of pressure from water around them, as well as to water’s movement as they pitched and rolled. With time the nerves became more refined, the hollows became tubes of seawater, and those tubes eventually closed off and buried themselves in the head. Further on in evolution, bones that were originally related to the jaw migrated and miniaturized, becoming the amplifying bones of the ear. The tubes dedicated to sensing rotational movement became our semicircular canals (balance), and it’s theorized that parts involved in sensing the pressure waves became our cochleas (hearing). In the composition of their salts, the fluids of our inner ear still carry the memory of that primordial ocean.

Within the human cochlea is a thin sensitive membrane, around thirty to thirty-five millimeters long, wound into a spiral and bathed in this salty fluid. This membrane resonates with sound, sensing from high to low frequency along its length, while associated nerve cells convey that resonance to the brain. To describe it simplistically, a cochlear implant is a series of very fine electrodes that lie along the length of the membrane. Sound is coded in a receiver behind the ear (often held on by magnets) and transmitted to electrodes, which then stimulate the nerve cells along the membrane in a way broadly analogous to sound. After William House’s first device in the early 1960s, during the next three decades groups in California, Melbourne, Vienna, and Utah worked almost independently on the research problem of how to optimize this ostensibly simple, but devilishly complicated, idea.

A wonderful essay.

Keep reading.

And at Amazon, I Can Hear You Whisper: An Intimate Journey Through the Science of Sound and Language.