Because the sensitiveness of the nerves of the ear becomes deadened. They do not convey to the brain such intense impulses when they are frequently acted upon by loud sounds.
991. Why do persons engaged in battle often lose their hearing?
Because the vibrations caused by the sounds of artillery are so violent that they overpower the mechanism of the ear, and frequently rupture the connection of the fine nervous filaments with the textures through which they spread.
The violent concussions of the air produced by volleys of cannon, or by loud peals of thunder, have an overpowering effect upon persons nervously constituted, and upon the organ of hearing, which is more especially affected. As persons have been struck blind by intense light, so others have been deafened by intense sounds. In 1697 a butcher's dog was killed by the noise of the firing to celebrate the proclamation of peace. Two troops of horse were dismounted, and drawn up in a line to fire volleys. At the moment of the first volley a large and courageous mastiff, belonging to a butcher, was lying asleep before the fire. At the noise of the first volley the dog started up, and ran into another room, where it hid itself behind a bed; on the firing of the second volley, it ran several times bout the room, trembling violently; and when the third volley was fired it ran around once or twice with great violence, and then dropped down dead, with blood flowing from its mouth and nose. Persons who are painfully affected by loud noises should put a little wool in their ears when such noises are occurring; they will thereby save themselves from temporary inconvenience, and probably preserve the sense of hearing from permanent injury.
Because minute particles of matter, diffused in the air, come in contact with the filaments of the olfactory nerve, which are spread out upon the walls of the nostrils, and those nerves transmit impressions to the brain, constituting what we call the odour of substances.
"And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul."—Genesis ii.