E and F. The labrynth of the ear, consisting of folds of membraneous tubes, filled with fluid, which serves to undulate with the vibrations of the tympanum, and thus gives clearness and precision to the sounds.
The auditory nerves are distributed in the tubes above described (the vestibule and the cochlea E F), and the nerves receive their impressions from the undulations of the fluid.
988. Why do we sometimes hear singing noises in the ear?
Because the ear is liable to inflammation from various causes, and when the blood flows unduly through the vessels of the ear it produces a slight sound.
"Apply thine heart unto instruction, and thine ears to the words of knowledge."—Proverbs xxiii.
989. Why do people become deaf?
Because the ear may be injured in various ways: the tympanum may be impaired, the fluid of the ear dried up, or the nerves be pressed upon by swellings in the surrounding parts. When, therefore, the mechanism of hearing is impaired, the sense of hearing becomes weakened, or altogether lost.
990. Why do persons accustomed to loud noises feel no inconvenience from them?