304 GENERAL SCIENCE 



nerves of hearing. The nerve fibers unite to form the 

 auditory nerve which carries the stimulus to the brain. 

 The brain interprets it in relation to loudness, quality, 

 pitch, the direction from which it came, and the distance 

 of its origin. From these characteristics, in the light of 

 previous knowledge and experience, the origin and cause 

 of the sound may be ascertained. 



210. Care of the Ears. Hard objects, such as pencils, 

 toothpicks, and matches, should not be pushed into the 

 auditory canal of the outer ear for fear of puncturing the 

 ear-drum. The wax, which keeps insects and dirt out 

 of the ear, sometimes collects in too large quantities and 

 hardens in the canal. It can be removed with the round 

 end of a hairpin by being careful not to shove the hairpin 

 in more than about three-fourths of an inch. The hard- 

 ened wax can also be softened by the use of warm water 

 and then easily removed. A person should never be 

 struck upon the ear with the open hand, because the ear- 

 drum may be injured by the air which is suddenly forced 

 into the auditory canal by the swiftly moving hand. The 

 Eustachian tube is sometimes closed at the throat end 

 during the time when a person has a cold, and then the 

 air pressure in the middle ear cannot be kept the same 

 as it is in the outer ear; this may result in the rupture 

 of the ear-drum and deafness may follow. To keep the 

 ears in good condition one should guard against all nose 

 and throat diseases. 



QUESTIONS AND EXERCISES 



1. Where are the vocal cords? Of what use are they? 



2. What parts of the body affect the voice? How is nasal 

 speech produced? 



3. Name the parts of the ear and the use of each. 



4. How do colds and throat diseases affect the ears? How 

 should you care for the ears? 



