Review Questions

1. From a technical and a historical viewpoint, what is the distinction between the terms microphone and transmitter?

2. What is meant by the terms transducer, electroacoustic transducer, passive electroacoustic transducer, and active electroaeoustic transducer?

3. What are the types of passive telephone transmitters? Of active transmitters? Which ones are used in practice?

4. How do the carbon granules function in a telephone transmitter?

5. What features are incorporated into handset transmitters so that they will be essentially non-resonant and non-positional?

6. What is meant by the term "capsule type" when applied to a telephone transmitter or receiver?

7. Distinguish between the use of the terms transmitter and receiver in telephony and radio.

8. For maximum power transfer, what should be the relation between the resistance of a transmitter and the resistance of the circuit into which it is to work?

9. Discuss the nature and reasons for the distortion caused by telephone transmitters.

10. How does the so-called "sound-powered" telephone operate. Will it operate as both a transmitter and a receiver? Explain.

11. What is an important advantage of the double-button carbon microphone? An important disadvantage?

12. Discuss the condenser microphone. For what scientific purposes is it used?

13. What features do the moving-coil and ribbon microphones have in common? In what respects do they differ greatly?

14. Explain the operation of the crystal microphone. What important precaution must be taken in its use?

15. Define the terms telephone receiver and loudspeaker.

16. Name the two principal parts of a receiver or loudspeaker.

17. What types of electroacoustic motor elements are possible, and what types are in practical use?

18. Discuss the receivers used in telephone sets.

19. Why is a transformer commonly used with the radio dynamic loudspeaker?

20. What types of acoustic radiators are used with loudspeakers? Discuss the principle of operation of each.

21. For the horn-type loudspeaker, discuss the air chamber, the throat, the mouth, and the rate of taper.

22. Discuss the nature and reasons for the distortion caused by telephone receivers.

23. Discuss the nature of the input impedance of a telephone receiver. If any peculiarities exist, explain the causes.

24. What are some of the improvements incorporated in telephone receivers of the capsule type?

25. Briefly discuss some of the miscellaneous receivers and loudspeakers that have been used.

26. What important problems are encountered in making tests on electroacoustic devices?

27. What are the approximate average power inputs to a telephone receiver, a radio-set dynamic loudspeaker, a large horn-type loudspeaker?

28. Give the approximate efficiencies of each device in Question 27.

29. The length of a loudspeaker horn sometimes is quite objectionable. What is a remedy if this general type of radiator must be used? Explain diagram-matically.

30. What are several important factors that must be determined when a sound system is to be designed for an auditorium?