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Updated: May 31, 2025
Experiment 157. To vibrate the tympanic membrane and the little ear-bones. Shut the mouth, and pinch the nose tightly. Try to force air through the nose. The air dilates the Eustachian tube, and is forced into the ear-drum. The distinct crackle, or clicking sound, is due to the movement of the ear-bones and the tympanic membrane.
Nevertheless, its development is not less interesting, and is explained with the same ease by comparative anatomy. In all the fishes and in the lowest Vertebrates there is no special apparatus for conducting sound, no external or middle ear; they have only a labyrinth, an internal ear, which lies within the skull. They are without the tympanum and tympanic cavity, and all its appendages.
It is a needless and dangerous practice, usually causing, in time, some form of inflammation. The abrasion of the skin in the canal thus produced affords a favorable soil for the growth of vegetable parasites. This, in turn, may lead to a chronic inflammation of the canal and of the tympanic membrane.
Lall mentions a horn from the cheek; Gregory reports one that measured 7 1/2 inches long that was removed from the temple of a woman in Edinburgh; Chariere of Barnstaple saw a horn that measured seven inches growing from the nape of a woman's neck; Kameya Iwa speaks of a dermal horn of the auricle; Saxton of New York has excised several horns from the tympanic membrane of the ear; Noyes speaks of one from the eyelid; Bigelow mentions one from the chin; Minot speaks of a horn from the lower lip, and Doran of one from the neck.
At the expiration of that time he begins to feel a peculiar corded and tympanic tightness about the epigastrium. A feverish condition of the brain, which sometimes amounts to absolute phantasia, now ensues, marked off into periods of increasing excitement by a heavy sleep, which, after each interval, grows fuller of tremendous dreams, and breaks up with a more intensely irritable waking.
Suggestion: The greatest diameter of the internal ear is about three fourths of an inch. In an extended course it is a profitable exercise to dissect the ear of a sheep or calf, observing the auditory canal, middle ear, bridge of bones, and the tympanic membrane with attached malleus and tensor tympanic muscle. Pass a probe from the nasal pharynx through the Eustachian tube into the middle ear.
This tube is generally closed, the air space behind the tympanic membrane being thus cut off from the external air. If, under these circumstances, the external air becomes denser, it will press the tympanic membrane inwards; if, on the other hand, the air on the other side becomes rarer, while the Eustachian tube becomes closed, the membrane will be pressed outwards.
In the Therapeutic Gazette, August 15, 1896, there is a translation of the report of a case by Voss, in which a child of five pushed a dry pea in his ear. Four doctors spent several days endeavoring to extract it, but only succeeded in pushing it in further. It was removed by operation on the fifth day, but suppuration of the tympanic cavity caused death on the ninth day.
He stated that a locust not weighing more than half a pennyweight, and that could not move an ounce weight, was supposed capable of setting 4 cubic miles of atmosphere into vibration, weighing 120,000,000 tons, so that it would be displaced 440 times in one second, and any portion of the air could bend the human tympanic membrane once in and once out 440 times in one second; and that 40,000,000 people, nearly the whole population of the United States, could have their 5,000 pounds of tympanic membrane thus shaken by an insect that could not move an ounce weight to save its life; and that the 231,222 pounds of tympanic membrane of the entire population of the earth, amounting to 1,350,000,000, who could conveniently stand in 11¼ square miles, would be affected the same way by 34 locusts stridulating in the air.
From the drum-head, or tympanic membrane, the vibrations, which are now those of a solid, are communicated by a series of very small bones, most beautifully linked together by perfect joints, to another membrane, which closes a small hole in the outer wall of the inner ear.
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