Taste, Smell, Hearing, and the Voice. 269 



Loudness of Voice. The loudness of the voice depends on the force 

 with which the air is driven past the cords, and on the size and con- 

 dition of the cords themselves. 



Pitch of Voice. Pitch depends on the rapidity of the vibrations, 

 which is determined by the length of the cords and their tension. 

 Other things being equal, the size of the larynx would determine the pitch. 



Voice and Speech. The larynx by itself produces vocal sound 

 merely. In speech the sounds produced in the larynx are much modi- 

 fied by the lips, tongue, teeth, cheeks, etc. We have voice as soon as 

 born, but we only gradually acquire the power of speech. This dis- 

 tinguishes man from the animals below him. 



Summary. i. Taste enables us to judge of the quality of food, and 

 it indirectly influences digestion. 



2. The tongue has two nerves of taste, the fifth pair of cranial nerves 

 supplying the front, and the ninth pair the base. 



3. So-called flavors affect the sense of smell more than that of taste. 



4. The sense of smell tests food and air. 



5. Agreeable odors promote respiration. 



6. The ear consists of the outer, middle, and inner ear. In the 

 inner ear are the endings of the auditory nerve. 



7. The semicircular canals have to do with the sense of equilibrium 

 and not with hearing. 



8. Colds and catarrh often seriously affect hearing. 



9. The larynx is very complicated. Various muscles move the car- 

 tilages and vary the length and tension of the vocal cords, and thus 

 produce the varying degrees of pitch. 



10. The vocal cords are not cords, but are band-like ridges on the 

 sides of the larynx. 



11. The higher animals have voice but not speech. 



12. Whispering is speech without voice. 



13. The larynx is affected by "colds" and catarrh. 



Questions. i . How may the sense of taste be blunted ? 



2. What is the effect of inhaling menthol ? 



3. Does a person who is deaf in one ear hear " half as well " as before ? 



4. Which of the senses goes to sleep first when we go to bed ? 



5. In what order do the other senses go to sleep ? 



6. In what order do the senses waken in the morning ? 



7. Why does one become hoarse from hearing others shouting ? 



