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1. The audible range of sound for human beings is

2. Sounds of frequency below 20 Hz are called

3. Sounds of frequency above 20000 Hz are called

4. Which animal can hear sounds up to 25 kHz?

5. As people grow older, their ears become

6. Which animals communicate using infrasound?

7. Before earthquakes, some animals get disturbed because

8. The vibrations of a pendulum fall under which sound category?

9. Ultrasound is produced by

10. Moths can detect bats because

11. The hearing aid converts sound waves into

12. The amplified electrical signals in a hearing aid are sent to

13. Ultrasound is used for cleaning because

14. Ultrasound can detect cracks in metal blocks because

15. Ordinary sound waves cannot be used to detect defects because

16. The technique of forming images of the heart using ultrasound is called

17. Ultrasonography is used to

18. During ultrasonography, ultrasonic waves are reflected from

19. Ultrasonography is used during pregnancy to

20. Ultrasound can be used to break kidney stones because