1. Conceptual Physics
Notes on Chapter 26
Sound

2. For Sound To Be Heard… You need 3 things:
1. a source that produces the sound
2. a medium to transmit the sound
3. an organ of the body that detects the sound
Sound enters the outer ear, vibrates eardrum, enters middle ear and vibrates liquid-filled inner ear.

3. For Sound To Be Heard…

4. Outer Ear The outer ear acts as funnel for the waves.
The waves travel through the ear canal and hit the lightly stretched membrane called the eardrum causing it to vibrate.
The vibrations then
enter the middle ear.

5. Middle Ear The middle ear contains the 3 smallest bones in the body.
hammer, anvil, stirrup
The vibrations travel
through the 3 bones
and are transmitted to
a liquid-filled inner ear.

6. Inner Ear The inner ear contains the cochlea. Cochlea is snail shaped
Contains liquid and hundreds of cell attached to nerve fibers
The nerve fibers form one larger nerve that travels to the brain where they are interpreted as sound

7. 26.1 Origin of Sound
All sounds are produced by the vibrations of material objects. Sound moves through a medium in the form of a longitudinal wave.
Frequency of the sound waves produced equals the frequency of the vibrating source.
Pitch describes our impressions about frequency or sound when produced by vibrations.
High- pitched sounds have a high frequency
Low-pitched sounds have a low frequency

8. NOTE: No human can hear above or below 20 - 20000 hertz.
26.1 Origin of Sound
A “normal” person can distinguish sound frequencies between 20 and 20,000 hertz.
below 20 hertz is known as infrasonic.
above 20,000 hertz is known as ultrasonic.
NOTE: No human can hear above or below hertz.

9. 26.2 Sound in Air
When something vibrates, it causes a wave that compresses and stretches.
In physics we call this Compression and Rarefaction.
For all wave motion, its not the medium that travels, but a pulse that travels.

10. 26.3 Media that Transmit Sound
Sound needs a medium to travel through. But sound travels at different speeds in different mediums.
Air --- can range from 330 m/s m/s
NOTE: For ALL problems we will take the average speed of 340 m/s
Liquid - can range from 1325 m/s m/s
NOTE: For water we will take the average speed of 1360 m/s (Water)
Solid - Can range from 4500 m/s m/s
NOTE: For solids we will take the average speed of 5100 m/s (Steel)

11. 26.4 Speed of Sound
Speed of sound in a gas depends on the temperature of the gas, and the mass of the particles in the gas.
Hear thunder after you see lightening
At 0⁰ C in dry air, sound travels 330 m/s or 1200 km/h
each degree above 0, the speed of sound increases by 0.60 m/s
Speed of sound in a solid depends on the materials elasticity (materials ability to change shape in response to an applied force, then resume its initial shape)
Steel is very elastic
Putty is inelastic

12. 26.5 Loudness
Loudness is subjective. Each person hears sound different due to each persons brain interrupts sound different.
Loudness is measured in Decibel (dB). Decibels are based on a logarithmic variation.
EX: 40 dB is 100 times as loud as 20 dB
100 dB is 10 times as loud as 90 dB
Physiological hearing damage begins at exposure to 85 dB.

14. 26.6 Natural Frequency
When any object composed of an elastic materials is disturbed, it vibrates at its own special set of frequencies- forms a special sound
Natural Frequency is the frequency at which the object vibrates when it is disturbed.
Depends on the elasticity and shape of the object.
Minimum energy is required to produced forced vibrations

15. 26.7 Forced Vibration
Forced vibration is when a vibrating object causes a object in contact with it to also vibrate.

16. 26.7 Forced Vibration
Sound boards are an important part of all stringed musical instruments because they are forced into vibration and produce the sound.
Without the sounding board, the sound would be barely audible.

17. 26.8 Resonance
Resonance occurs when the frequency of a vibration forced on an object matches the object’s natural frequency, causing a dramatic increase in amplitude.
An object resonates when there is a force to pull it back to its starting position and enough energy to keep it vibrating.

18. 26.9 Interference
Interference of sound waves affects the loudness of sounds.

19. 26.9 Interference
When constructive interference occurs with sound waves, the listener hears a louder sound. – Increase in Amplitudes
When destructive interference occurs, the listener hears a fainter sound or no sound at all. – Decrease in Amplitudes
Antinoise technology uses destructive interference
The crest of a transverse wave corresponds to the compression of a sound wave- the trough corresponds to the rarefaction.

20. Sound
Different objects create different sound waves.

21. Sound
Sound waves can produce HARMONICS.

22. Sound
Harmonics can be easily demonstrated with a tuning fork and tube.

23. 26.10 Beats
Beats happen when two waves interfere with each other in a way that some of the wave energy overlaps constructively and some overlap destructively.
DEF- Periodic variation in the loudness of a sound

24. Sound
If you subtract the frequencies of the two tuning forks, you can get the beat frequency.
EX: 262 Hz and 266 Hz
262 Hz and 272 Hz

25. Conceptual Physics
Notes on Chapter 26
Sound

26. For Sound To Be Heard… You need 3 things:
1. a _________ that produces the sound
2. a _________ to transmit the sound
3. an ________ of the body that detects the sound
Sound enters the outer ear, ___________ eardrum, enters middle ear and vibrates liquid-filled inner ear.

27. For Sound To Be Heard…

28. Outer Ear The outer ear acts as _______ for the waves.
The waves travel through the ear canal and hit the lightly stretched membrane called ______ __________ causing it to vibrate.
The vibrations then
enter the _______ ___.

29. Middle Ear The middle ear contains the 3 smallest bones in the body.
_______, __________, __________
The vibrations travel
through the 3 bones
and are transmitted to
a liquid-filled inner ear.

30. Inner Ear The inner ear contains the ____________.
Cochlea is snail shaped
Contains liquid and hundreds of cell attached to _________ _________
The nerve fibers form one larger nerve that travels to the brain where they are interpreted as sound

31. 26.1 Origin of Sound
All sounds are produced by the vibrations of material objects. Sound moves through a medium in the form of a _______________ _________.
Frequency of the sound waves produced equals the frequency of the vibrating source.
__________ describes our impressions about frequency or sound when produced by vibrations.
High- pitched sounds have a ______ ___________________
Low-pitched sounds have a _______ ___________________

32. NOTE: No human can hear above or below 20 - 20000 hertz.
26.1 Origin of Sound
A “normal” person can distinguish sound frequencies between 20 and 20,000 hertz.
below 20 hertz is known as ______________
above 20,000 hertz is known as ____________
NOTE: No human can hear above or below hertz.

33. 26.2 Sound in Air
When something vibrates, it causes a wave that ____________ and _________.
In physics we call this Compression and Rarefaction.
For all wave motion, its not the medium that travels, but a ________ that travels.

34. 26.3 Media that Transmit Sound
Sound needs a medium to travel through. But sound travels at different speeds in different mediums.
Air --- can range from _________ - _________
NOTE: For ALL problems we will take the average speed of 340 m/s
Liquid - can range from _______ - _________
NOTE: For water we will take the average speed of 1360 m/s (Water)
Solid - Can range from ________ - _________
NOTE: For solids we will take the average speed of 5100 m/s (Steel)

35. 26.4 Speed of Sound
Speed of sound in a gas depends on ______________ of the gas, and _______________________ in the gas.
Hear thunder after you see lightening
At 0⁰ C in dry air, sound travels 330 m/s or 1200 km/h
Each degree above 0, the speed of sound increases by 0.60 m/s
Speed of sound in a solid depends on the materials ______________ (materials ability to change shape in response to an applied force, then resume its initial shape)
Steel ________________
Putty ________________

36. 26.5 Loudness
Loudness is ______________. Each person hears sound different due to each persons brain interrupts sound different.
Loudness is measured in _________________ . Decibels are based on a logarithmic variation.
EX: 40 dB is 100 times as loud as 20 dB
100 dB is 10 times as loud as 90 dB
Physiological hearing damage begins at exposure to ______dB.

38. 26.6 Natural Frequency
When any object composed of an elastic materials is disturbed, it vibrates at its own special set of frequencies- forms a special sound
__________________ is the frequency at which the object vibrates when it is disturbed.
Depends on the _____________ and ________ of the object.
Minimum energy is required to produced forced vibrations

39. 26.7 Forced Vibration
___________________ is when a vibrating object causes a object in contact with it to also vibrate.

40. 26.7 Forced Vibration
____________________ are an important part of all stringed musical instruments because they are forced into vibration and produce the sound.
Without the sounding board, the sound would be _______________________.

41. 26.8 Resonance
Resonance occurs when the frequency of a vibration forced on an object matches __________________________, causing a dramatic increase in amplitude.
An object resonates when there is a force to pull it back to its starting position and enough energy to keep it vibrating.

42. 26.9 Interference
Interference of sound waves affects the loudness of sounds.

43. 26.9 Interference
When _______________ interference occurs with sound waves, the listener hears a louder sound. – Increase in Amplitudes
When ______________ interference occurs, the listener hears a fainter sound or no sound at all. – Decrease in Amplitudes
Antinoise technology uses destructive interference
The _______ of a transverse wave corresponds to the ________________ of a sound wave- the _________ corresponds to the ________________.

44. Sound
Different objects create different sound waves.

45. Sound
Sound waves can produce _____________.

46. Sound
Harmonics can be easily demonstrated with a tuning fork and tube.

47. 26.10 Beats
Beats happen when two waves interfere with each other in a way that some of the wave energy overlaps constructively and some overlap destructively.
DEF- Periodic variation in the loudness of a sound

48. Sound
If you subtract the frequencies of the two tuning forks, you can get the beat frequency.
EX: 262 Hz and 266 Hz
262 Hz and 272 Hz