Cords of Corti

December 1, 1909
"Schubert concert to-night: Marie and I submitted our cords of corti and sensoria to the beats and agitation of the voices and instruments; we accorded them a sensitive response of varying approval."......Edwin Manners

"Ordinary musical tones, the notes of the
voice, the violin, and the piano, for example,
simple as they sound, are, like ordinary white
light, rather complex compounds of many sim-
ple elements. There are in them seven or eight
constituent or " partial " tones, quite distinctly
audible to the trained ear or to the untrained
ear armed with suitable instruments ; and these
partial tones, produced by vibrations in the
sound-emitting body whose rates are regularly
related, bear a certain fixed relation to each
other, like the spectrum-colors that compose
white light.Not only this, but each partial tone arouses its own sensation in the ear by stimulating there one of the minute filaments called the cords of Corti, each of which vibrates sympathetically to a tone of given pitch and to no other. Now we are to imagine that
when an ordinary musical tone is sounded, seven
or eight of these little cords immediately
start a-tremble, and send to the brain their mes-
sages, which combine there into the composite
impression we name " a tone." If now another
tone is sounded, one which starts into motion
another set of filaments, and if furthermore
there is one filament now set in motion that was
also excited by the first compound tone if, in
other words, the two tones happen to have a
partial tone in common, which in both instances
excites the same filament in the ear, then we
shall have a sense of close relationship between
them ; they will make together a harmonic
group or form."

FROM GRIEG TO
BRAHMS
STUDIES OF SOME MODERN
COMPOSERS AND THEIR ART
BY
DANIEL GREGORY MASON
1902

Organ of Corti

From Wikipedia

The organ of Corti (or spiral organ) is the organ in the inner ear of mammals that contains auditory sensory cells, or "hair cells."

The organ of Corti has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. It contains between 15,000-20,000 auditory nerve receptors. Each receptor has its own hair cell. The shear on the hairs opens ion channels, leading to neural, electrical signaling to the auditory cortex. The pinna and middle ear act as mechanical transformers, so that by the time sound waves reach the Organ of Corti, their pressure amplitude is 20 times that of the air impinging on the pinna. The Organ of Corti can be damaged by excessive sound levels, leading to noise induced health effects. The organ of corti is the structure that transduces pressure waves to action potential.

The discoverer: Alfonso Corti

The organ was named after the Italian anatomist Marquis Alfonso Giacomo Gaspare Corti (1822-1876), who conducted microscopic research of the mammalian auditory system.

Hearing impairment

The most common kind of hearing impairment, sensorineural hearing loss, includes as one major cause the reduction of function in the organ of Corti. Specifically, the active amplification function of the outer hair cells is very sensitive to damage from exposure to trauma from overly-loud sounds or to certain "ototoxic" drugs. Once outer hair cells are damaged, they do not regenerate, and the result is a loss of sensitivity and an abnormally large growth of loudness (known as recruitment) in the part of the spectrum that the damaged cells serve.