Hearing Sound

1. Hearing Sound

2. Have you ever felt sound?

3. Have you ever felt sound? • Car with really loud music playing (especially with heavy base).

4. Did you know? • Thunder and lightening are essentially the same event?

5. Did you know? • Thunder and lightening are essentially the same event? • How can this be?????

6. Did you know? • Thunder and lightening are essentially the same event? • How can this be????? • Light travels at 299,792 m/sec. • Sound travels at 335 m/sec.

7. Can humans or animals hear better?

8. Can humans or animals hear better? • Remember that sound is a vibration.

9. Can humans or animals hear better? • Remember that sound is a vibration. • Well….the frequency of a sound wave is the number of vibrations (waves) per second.

10. Can humans or animals hear better? • Remember that sound is a vibration. • Well….the frequency of a sound wave is the number of vibrations (waves) per second. • We measure this in something called a Hertz (Hz).

11. Can humans or animals hear better? • Remember that sound is a vibration. • Well….the frequency of a sound wave is the number of vibrations (waves) per second. • We measure this in something called a Hertz (Hz). • 1Hz = 1 wave per second

12. Can humans or animals hear better?

13. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz.

14. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz. • Dogs can hear up to about 25,000 Hz.

15. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz. • Dogs can hear up to about 25,000 Hz. • Cats can hear up to about 65,000 Hz.

16. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz. • Dogs can hear up to about 25,000 Hz. • Cats can hear up to about 65,000 Hz. • >20,000 Hz = ultrasonic.

17. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz. • Dogs can hear up to about 25,000 Hz. • Cats can hear up to about 65,000 Hz. • >20,000 Hz = ultrasonic. • <20 Hz = infrasonic.

18. Can humans or animals hear better? • Humans hear from about 20 to 20,000 Hz. • Dogs can hear up to about 25,000 Hz. • Cats can hear up to about 65,000 Hz. • >20,000 Hz = ultrasonic. • <20 Hz = infrasonic. • Elephants communicate at this level.

19. Some common noises:

20. Some common noises: • 20 (dB) = whispers

21. Some common noises: • 20 (dB) = whispers • 40-50 (dB) = Average home

22. Some common noises: • 20 (dB) = whispers • 40-50 (dB) = Average home • 70 (dB) = City street

23. Some common noises: • 20 (dB) = whispers • 40-50 (dB) = Average home • 70 (dB) = City street • 115 (dB) = rock concert

24. Some common noises: • 20 (dB) = whispers • 40-50 (dB) = Average home • 70 (dB) = City street • 115 (dB) = rock concert • 140-170 (dB) = jet engine

25. Some common noises: • 20 (dB) = whispers • 40-50 (dB) = Average home • 70 (dB) = City street • 115 (dB) = rock concert • 140-170 (dB) = jet engine • 85 (dB) or higher for extended periods of time can cause permanent hearing loss

26. Ear Canal

27. The human ear: Parts of the ear

28. The human ear: Parts of the ear • Outer ear: funnels sound waves.

29. The human ear: Parts of the ear • Outer ear: funnels sound waves. • Ear canal: a few cm long and ends at the eardrum.

30. The human ear: Parts of the ear • Outer ear: funnels sound waves. • Ear canal: a few cm long and ends at the eardrum. • Eardrum: A small, tightly stretched, drum-like membrane that vibrates when hit by sound waves.

31. The human ear: Parts of the ear • Middle ear: Contains the three smallest bones in the human body.

32. The human ear: Parts of the ear • Middle ear: Contains the three smallest bones in the human body. • Hammer: Attached to the eardrum and vibrates and hits the anvil.

33. The human ear: Parts of the ear • Middle ear: Contains the three smallest bones in the human body. • Hammer: Attached to the eardrum and vibrates and hits the anvil. • Anvil: shakes the stirrup.

34. The human ear: Parts of the ear • Middle ear: Contains the three smallest bones in the human body. • Hammer: Attached to the eardrum and vibrates and hits the anvil. • Anvil: shakes the stirrup. • Stirrup: vibrates against the membrane separating the middle and inner ear.

35. The human ear: Parts of the ear • Inner ear: Separated from middle ear by a membrane.

36. The human ear: Parts of the ear • Inner ear: Separated from middle ear by a membrane. • Cochlea: cavity of the inner ear filled with liquid and Lined with thousands of tiny hairs.

37. The human ear: Parts of the ear • Inner ear: Separated from middle ear by a membrane. • Cochlea: cavity of the inner ear filled with liquid and Lined with thousands of tiny hairs. • The vibrations are passed from stirrup to membrane to liquid to hairs (which sway back and forth).

38. The human ear: Parts of the ear • Inner ear: Separated from middle ear by a membrane. • Cochlea: cavity of the inner ear filled with liquid and Lined with thousands of tiny hairs. • The vibrations are passed from stirrup to membrane to liquid to hairs (which sway back and forth). • The hairs are attached to nerve cells that detect movement and send messages to the brain.

39. Applications of Sound: • Sonar: (Sound navigation and ranging). • Measuring the time it takes to detect a reflected sound wave.

40. Applications of Sound: • Ultrasound and infrasound: • Dog whistles (ultrasonic) • Elephants stomping on the ground (produce sound waves too low for humans to hear). (infrasonic)

41. Applications of Sound: • Ultrasound (Echolocation): • Using sound waves to determine distances or locate objects. • Dolphins • Bats

42. Applications of Sound: • Ultrasound (other uses): • Medicine • Brushing your teeth • Jewelry cleaners • Some cameras (automatic focus)