106 SOUND 



The pitch of the voice is raised or lowered by drawing 

 the cords more or less tightly ; loudness depends upon the 

 energy with which the air is driven out, and quality 

 upon the shape and movements of the throat and mouth. 

 /Speech is made by movements of the lips, tongue, palate, 

 teeth, and other parts of the air passages. We form 

 words mainly by varying the quality of the voice ; but 

 among some nations, like the Chinese, pitch also is of 

 importance in talking. 



QUESTIONS 



1. Define a tone. Explain the difference between a pure tone 

 and a mixed noise. 



2. In what ways may tones differ from each other ? 



3. What is meant by loudness? Upon what different con- 

 ditions may it depend? Show how ear trumpets help to make 

 sounds louder. 



4. Name some familiar sounds that have a high pitch, and 

 some having a low pitch. Upon what doe's pitch depend? 

 How? Do short waves or long waves have the higher rate of 

 vibration? 



5. What is the lowest, and what the highest, number of vibra- 

 tions per second that the ear generally can hear? How many 

 vibrations per second has middle C? 



6. Give an example of two tones differing only in quality. 

 What determines the quality of a tone or sound? What is an 

 overtone ? 



7. In music, what is a chord ? 



8. Explain how the voice is produced. How is the pitch of 

 the voice varied ? How do we vary its loudness and quality ? 



9. How is speech effected ? Do dumb persons have a voice ? 

 Why can they not talk? 



10. Name some different musical instruments. Classify each 

 as a stringed instrument or a wind instrument, etc. 



