Man's physical universe

xanabras

SOUND PRODUCED BY VIBRATIONS IN MATTER 459

14. What is the effect on the pitch of the sound produced by a sound motionpicture

machine when the film is speeded up?

15. How fast would an airplane have to travel in order to catch up with the

sound waves produced by its motor?

16. Suggest several reasons why sounds carry better on a foggy night than on a

hot, clear, windy day.

17. In what respect is it correct to speak of supersonic waves as soundless sound

waves?

18. Discuss some of the applications of supersonic frequencies.

19. What is meant by "noise deafness"?

20. Describe the human ear and explain why it is possible to hear and recognize

several sounds simultaneously.

21. What is the Doppler effect? Illustrate with some examples.

22. W'hat is the frequency range to which the human ear is sensitive?

23. Discuss the principle of the phonograph.

24. What is meant by the statement that a speech has been broadcast by electrical

transcription? What are the advantages which electrical transcription

makes possible to radio broadcasting?

25. Suggest some possible uses of electrical transcription in the school.

26. What is meant by saying that sound waves are compressional waves?

27. Mention some of the consequ-ences of the relatively small velocity of sound

in air.

28. What other information besides the time required for a sound to travel from

a ship to the ocean bottom and back again would be required to determine

the depth of water by depth-sounding devices?

29. In what respect would an airplane position-finder based on the reflection of

electromagnetic waves be superior to one based on the reflection of sound

waves?

30. Compare living in the country with living in a city from the point of view of

sound.

31. What are some of the modern trends in the elimination of noise in cities?

32. Discuss social intelligence as applied to the use of a radio.

33. Discuss the factors which control the intensity of sound.

34. Differentiate between the intensity and loudness of sound.

35. Would ultrasonic sound waves be more or less intense than audible sound

waves of the same amplitude? Why, or why not?

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