Sound and Music Review


Part A: TRUE/FALSE

1. Which of the following statements are TRUE of sound waves? Identify all that apply.

  1. A sound wave is a mechanical wave.
  2. A sound wave is a means of transporting energy without transporting matter.
  3. Sound can travel through a vacuum.
  4. A sound wave is a pressure wave; they can be thought of as fluctuations in pressure with respect to time.
  5. A sound wave is a transverse wave.
  6. To hear the sound of a tuning fork, the tines of the fork must move air from the fork to one's ear.
  7. Most (but not all) sound waves are created by a vibrating object of some type.
  8. To be heard, a sound wave must cause a relatively large displacement of air (for instance, at least a cm or more) around an observer's ear.

 

2. Which of the following statements are TRUE of sound intensity and decibel levels? Identify all that apply.

  1. The intensity of a sound wave has units of Watts/meter.
  2. When a sound wave is said to be intense, it means that the particles are vibrating back and forth at a high frequency.
  3. Intense sounds are characterized by particles of the medium vibrating back and forth with a relatively large amplitude.
  4. Intense sounds are usually perceived as loud sounds.
  5. The ability of an observer to hear a sound wave depends solely upon the intensity of the sound wave.
  6. From the least intense to the most intense, humans have a rather narrow range of intensity over which sound waves can be heard.
  7. The intensity of sound which corresponds to the threshold of pain is one trillion times more intense than the sound which corresponds to the threshold of hearing.
  8. Two sounds which have a ratio of decibel ratings equal to 2.0. This means that the second sound is twice as intense as the first sound.
  9. Sound A is 20 times more intense than sound B. So if Sound B is rated at 30 dB, then sound A is rated at 50 dB.
  10. Sound C is 1000 times more intense than sound D. So if sound D is rated at 80 dB, sound C is rated at 110 dB.
  11. A machine produces a sound which is rated at 60 dB. If two of the machines were used at the same time, the decibel rating would be 120 dB.
  12. Intensity of a sound at a given location varies directly with the distance from that location to the source of the sound.
  13. If the distance from the source of sound is doubled then the intensity of the sound will be quadrupled.
  14. If the distance from the source of sound tripled, then the intensity of the sound will be increased by a factor of 6.

 

3. Which of the following statements are TRUE of the speed of sound? Identify all that apply.

  1. The speed of a sound wave depends upon its frequency and its wavelength.
  2. In general, sound waves travel fastest in solids and slowest in gases.
  3. Sound waves travel fastest in solids (compared to liquids and gases) because solids are more dense.
  4. The fastest which sound can move is when it is moving through a vacuum.
  5. If all other factors are equal, a sound wave will travel fastest in the most dense materials.
  6. A highly elastic material has a strong tendency to return to its original shape if stressed, stretched, plucked or somehow disturbed.
  7. A more rigid material such as steel has a higher elasticity and therefore sound tends to move through it at high speeds.
  8. The speed of sound moving through air is largely dependent upon the frequency and intensity of the sound wave.
  9. A loud shout will move faster through air than a faint whisper.
  10. Sound waves would travel faster on a warm day than a cool day.
  11. The speed of a sound wave would be dependent solely upon the properties of the medium through which it moves.
  12. A shout in a canyon produces an echo off a cliff located 127 m away. If the echo is heard 0.720 seconds after the shout, then the speed of sound through the canyon is 176 m/s.
  13. The speed of a wave within a guitar string varies inversely with the tension in the string.
  14. The speed of a wave within a guitar string varies inversely with the mass per unit length of the string.
  15. The speed of a wave within a guitar string will be doubled if the tension of the string is doubled.
  16. An increase in the tension of a guitar string by a factor of four will increase the speed of a wave in the string by a factor of two.
  17. An increase in the linear mass density of a guitar string by a factor of four will increase the speed of a wave in the string by a factor of two.

 

4. Which of the following statements are TRUE of the frequency of sound and the perception of pitch? Identify all that apply.

  1. A high pitched sound has a low wavelength.
  2. A low-pitched sound is a sound whose pressure fluctuations occur with a low period.
  3. If an object vibrates at a relatively high frequency, then the pitch of the sound will be low.
  4. The frequency of a sound will not necessarily be the same as the frequency of the vibrating object since sound speed will be altered as the sound is transmitted from the object to the air and ultimately to your ear.
  5. Two different guitar strings are used to produce a sound. The strings are identical in terms of material, thickness and the tension to which they are pulled. Yet string A is shorter than string B. Therefore, string A will produce a lower pitch.
  6. Both low- and high-pitched sounds will travel through air at the same speed.
  7. Doubling the frequency of a sound wave will halve the wavelength but not alter the speed of the wave.
  8. Tripling the frequency of a sound wave will decrease the wavelength by a factor of 6 and alter the speed of the wave.
  9. Humans can pretty much hear a low-frequency sound as easily as a high-frequency sound.
  10. Ultrasound waves are those sound waves with frequencies less than 20 Hz.

 

5. Which of the following statements are TRUE of standing wave patterns? Identify all that apply.

  1. A standing wave pattern is formed as a result of the interference of two or more waves.
  2. When a standing wave pattern is established, there are portions of the medium which are not disturbed.
  3. A standing wave is really not a wave at all; it is a pattern resulting from the interference of two or more waves which are traveling through the same medium.
  4. A standing wave pattern is a regular and repeating vibrational pattern established within a medium; it is always characterized by the presence of nodes and antinodes.
  5. An antinode on a standing wave pattern is a point which is stationary; it does not undergo any displacement from its rest position.
  6. For every node on a standing wave pattern, there is a corresponding antinode; there are always the same number of each.
  7. When a standing wave pattern is established in a medium, there are alternating nodes and antinodes, equally spaced apart across the medium.

 

6. Which of the following statements are TRUE of the concept of resonance? Identify all that apply.

  1. A musical instrument can play any frequency imaginable.
  2. All musical instruments have a natural frequency or set of natural frequencies at which they will vibrate; each frequency corresponds to a unique standing wave pattern.
  3. The result of two objects vibrating in resonance with each other is a vibration of larger amplitude.
  4. Objects which share the same natural frequency will often set each other into vibrational motion when one is plucked, strummed, hit or otherwise disturbed. This phenomenon is known as a forced resonance vibration.
  5. A vibrating tuning fork can set a second tuning fork into resonant motion.
  6. The resonant frequencies of a musical instrument are related by whole number ratios.

 

7. Which of the following statements are TRUE of the harmonics and standing wave patterns in guitar strings? Identify all that apply.

  1. The fundamental frequency of a guitar string is the highest frequency at which the string vibrates.
  2. The fundamental frequency of a guitar string corresponds to the standing wave pattern in which there is a complete wavelength within the length of the string.
  3. The wavelength for the fundamental frequency of a guitar string is 2.0 m.
  4. The wavelength for the second harmonic played by a guitar string is two times the wavelength of the first harmonic.
  5. The standing wave pattern for the fundamental played by a guitar string is characterized by the pattern with the longest possible wavelength.
  6. If the fundamental frequency of a guitar string is 200 Hz, then the frequency of the second harmonic is 400 Hz.
  7. If the frequency of the fifth harmonic of a guitar string is 1200 Hz, then the fundamental frequency of the same string is 6000 Hz.
  8. As the frequency of a standing wave pattern is tripled, its wavelength is tripled.
  9. If the speed of sound in a guitar string is 300 m/s and the length of the string is 0.60 m, then the fundamental frequency will be 180 Hz.
  10. As the tension of a guitar string is increased, the fundamental frequency produced by that string is decreased.
  11. As the tension of a guitar string is increased by a factor of 2, the fundamental frequency produced by that string is decreased by a factor of 2.
  12. As the linear density of a guitar string is increased, the fundamental frequency produced by the string is decreased.
  13. As the linear density of a guitar string is increased by a factor 4, the fundamental frequency produced by the string is decreased by a factor of 2.

 

8. Which of the following statements are TRUE of the harmonics and standing wave patterns in air columns? Identify all that apply.

  1. The speed of the waves for the various harmonics of open-end air columns are whole number multiples of the speed of the wave for the fundamental frequency.
  2. Longer air columns will produce lower frequencies.
  3. The pitch of a sound can be increased by shortening the length of the air resonating inside of an air column.
  4. An open end of an air column allows air to vibrate a maximum amount whereas a closed end forces air particles to behave as nodes.
  5. Open-end air columns have antinodes positioned at each end while closed-end air columns have nodes positioned at each end.
  6. Closed-end air columns can only produce odd-numbered harmonics.
  7. Open-end air columns can only produce even-numbered harmonics.
  8. A closed-end air column that can play a fundamental frequency of 250 Hz cannot play 500 Hz.
  9. An open-end air column that can play a fundamental frequency of 250 Hz cannot play 750 Hz.
  10. A closed-end air column has a length of 20 cm. The wavelength of the first harmonic is 5 cm.
  11. An open-end air column has a length of 20 cm. The wavelength of the first harmonic is 10 cm.
  12. Air column A is a closed-end air column. Air column B is an open-end air column. Air column A would be capable of playing lower pitches than air column B.
  13. The speed of sound in air is 340 m/s. An open-end air column has a length of 40 cm. The fundamental frequency of this air column is approximately 213 Hz.
  14. The speed of sound in air is 340 m/s. A closed-end air column has a length of 40 cm. The fundamental frequency of this air column is approximately 213 Hz.
  15. If an open-end air column has a fundamental frequency of 250 Hz, then the frequency of the fourth harmonic is 1000 Hz.
  16. If a closed-end air column has a fundamental frequency of 200 Hz, then the frequency of the fourth harmonic is 800 Hz.

 

9. Which of the following statements are TRUE of sound interference and beats? Identify all that apply.

  1. Beats result when two sounds of slightly different frequencies interfere.
  2. Beats are characterized by a sound whose frequency is rapidly fluctuating between a high and a low pitch.
  3. Two sounds with a frequency ratio of 2:1 would produce beats with a beat frequency of 2 Hz.
  4. Two tuning forks are sounding out at slightly different frequencies - 252 Hz and 257 Hz. A beat frequency of 5 Hz will be heard.
  5. A piano tuner is using a 262 Hz tuning fork in an effort to tune a piano string. She plucks the string and the tuning fork and observes a beat frequency of 2 Hz. Therefore, she must lower the frequency of the piano string by 2 Hz.

 

 

Part B: Multiple Choice

10. What type of wave is produced when the particles of the medium are vibrating to and fro in the same direction of wave propagation?

a. longitudinal wave.

b. sound wave.

c. standing wave.

d. transverse wave.

 

11. When the particles of a medium are vibrating at right angles to the direction of energy transport, the type of wave is described as a _____ wave.

a. longitudinal

b. sound

c. standing

d. transverse

 

12. A transverse wave is traveling through a medium. See diagram below. The particles of the medium are moving.

a. parallel to the line joining AD.

b. along the line joining CI.

c. perpendicular to the line joining AD.

d. at various angles to the line CI.

e. along the curve CAEJGBI.

 

 

13. If the energy in a longitudinal wave travels from south to north, the particles of the medium ____.

a. move from north to south, only.

b. vibrate both north and south.

c. move from east to west, only.

d. vibrate both east and west.

 

14. The main factor which effects the speed of a sound wave is the ____.

a. amplitude of the sound wave

b. intensity of the sound wave

c. loudness of the sound wave

d. properties of the medium

e. pitch of the sound wave

 

 

15.  As a wave travels into a medium in which its speed increases, its wavelength ____.

a. decreases

b. increases

c. remains the same

 

16. As a wave passes across a boundary into a new medium, which characteristic of the wave would NOT change?

a. speed

b. frequency

c. wavelength

 

17. The ____ is defined as the number of cycles of a periodic wave occurring per unit time.

a. wavelength

b. period

c. amplitude

d. frequency

 

18. Many wave properties are dependent upon other wave properties. Yet, one wave property is independent of all other wave properties. Which one of the following properties of a wave is independent of all the others?

a. wavelength

b. frequency

c. period

d. velocity

 

 

19. Consider the motion of waves in a wire. Waves will travel fastest in a ____ wire.

a. tight and heavy

b. tight and light

c. loose and heavy

d. loose and light

 

20. TRUE or FALSE:

The SI unit for frequency is hertz.

a. True

 

b. False

 

 

21. TRUE or FALSE:

Doubling the frequency of a sound source doubles the speed of the sound waves which it produces.

a. True

 

b. False

 

 

 22. A sound wave has a wavelength of 3.0 m. The distance between the center of a compression and the center of the next adjacent rarefaction is ____.

a. 0.75 m.

b. 1.5 m.

c. 3.0 m.

d. 6.0 m.

e. impossible to calculate without knowing frequency.

 

23.  Which one of the following factors determines the pitch of a sound?

a. The amplitude of the sound wave

b. The distance of the sound wave from the source

c. The frequency of the sound wave

d. The phase of different parts of the sound wave

e. The speed of the sound wave

 

 

24. A certain note is produced when a person blows air into an organ pipe. The manner in which one blows on a organ pipe (or any pipe) will effect the characteristics of the sound which is produced. If the person blows slightly harder, the most probable change will be that the sound wave will increase in ____.

a. amplitude

b. frequency

c. pitch

d. speed

e. wavelength

 

25. A vibrating object with a frequency of 200 Hz produces sound which travels through air at 360 m/s. The number of meters separating the adjacent compressions in the sound wave is ____.

a. 0.90

b. 1.8

c. 3.6

d. 7.2

e. 200

 

26. Consider the diagram below of several circular waves created at various times and locations. The diagram illustrates ____.

a. interference

b. diffraction

c. the Doppler effect.

d. polarization

 

27. In the diagram above, a person positioned at point A would perceive __________ frequency as the person positioned at point B.

a. a higher

b. a lower

c. the same

 

28. A girl moves away from a source of sound at a constant speed. Compared to the frequency of the sound wave produced by the source, the frequency of the sound wave heard by the girl is ____.

a. lower.

b. higher.

c. the same.

 

29. An earth-based receiver is detecting electromagnetic waves from a source in outer space. If the frequency of the waves are observed to be increasing, then the distance between the source and the earth is probably ____.

a. decreasing.

b. increasing.

c. remaining the same.

 

30. As two or more waves pass simultaneously through the same region, ____ can occur.

a. refraction

b. diffraction

c. interference

d. reflection

 

31. TRUE or FALSE:

If two crests meet while passing through the same medium, then constructive interference occurs.

a. True

b. False

 

32. A node is a point along a medium where there is always ____.


a. a crest meeting a crest

b. a trough meeting a trough

c. constructive interference

d. destructive interference

e. a double rarefaction.

 

 

33. TRUE or FALSE:

It is possible that one vibrating object can set another object into vibration if the natural frequencies of the two objects are the same.

a. True

b. False

 

34. An object is vibrating at its natural frequency. Repeated and periodic vibrations of the same natural frequency impinge upon the vibrating object and the amplitude of its vibrations are observed to increase. This phenomenon is known as ____.

a. beats

b. fundamental

c. interference

d. overtone

e. resonance

 

35. A standing wave experiment is performed to determine the speed of waves in a rope. The standing wave pattern shown below is established in the rope. The rope makes 90.0 complete vibrational cycles in exactly one minute. The speed of the waves is ____ m/s.

a. 3.0

b. 6.0

c. 180

d. 360

e. 540

 

36. Standing waves are produced in a wire by vibrating one end at a frequency of 100. Hz. The distance between the 2nd and the 5th nodes is 60.0 cm. The wavelength of the original traveling wave is ____ cm.

a. 50.0

b. 40.0

c. 30.0

d. 20.0

e. 15.0

 

37. Consider the standing wave pattern shown below. A wave generated at the left end of the medium undergoes reflection at the fixed end on the right side of the medium. The number of antinodes in the diagram is

a. 3.0

b. 5.0

c. 6.0

d. 7.0

e. 12

 

38. The standing wave pattern in the diagram above is representative of the ____ harmonic.

a. third

b. fifth

c. sixth

d. seventh

e. twelfth

 

39. The distance between successive nodes in any standing wave pattern is equivalent to ____ wavelengths.

a. 1/4

b. 1/2

c. 3/4

d. 1

e. 2.

 

40. A vibrating tuning fork is held above a closed-end air column, forcing the air into resonance. If the sound waves created by the tuning fork have a wavelength of W, then the length of the air column could NOT be ____.

a. 1/4 W

b. 2/4 W

c. 3/4 W

d. 5/4 W

e. 7/4 W

 

41. TRUE or FALSE:

A vibrating tuning fork is held above an air column, forcing the air into resonance. The length of the air column is adjusted to obtain various resonances. The sound waves created by the tuning fork have a wavelength of W.  The difference between the successive lengths of the air column at which resonance occurs is 1/2 W.

a. True

b. False

 

42. TRUE or FALSE:

An organ pipe which is closed at one end will resonate if its length is equal to one-half of the wavelength of the sound in the pipe.

a. True

b. False

 

43. A 20-cm long pipe is covered at one end in order to create a closed-end air column. A vibrating tuning fork is held near its open end, forcing the air to vibrate in its first harmonic. The wavelength of the standing wave pattern is ____.

a. 5 cm

b. 10 cm

c. 20 cm

d. 40 cm

e. 80 cm

 

44. A stretched string vibrates with a fundamental frequency of 100. Hz. The frequency of the second harmonic is ____.

a. 25.0 Hz

b. 50.0 Hz

c. 100. Hz

d. 200. Hz

e. 400. Hz

 

45. A 40.0-cm long plastic tube is open at both ends and resonating in its first harmonic. The wavelength of the sound which will produce this resonance is ____.

a. 10.0 cm

b. 20.0 cm

c. 40.0 cm

d. 80.0 cm

e. 160. cm

 

46. The diagrams below represent four different standing wave patterns in air columns of the same length. Which of the columns is/are vibrating at its/their fundamental frequency? Include all that apply.

 

 

47. The diagrams above (Question #46) represent four different standing wave patterns in air columns of equal length. Which of the columns will produce the note having the highest pitch?

a. A

b. B

c. C

d. D

e. All column produce notes having the same pitch

 

48. An air column closed at one end filled with air resonates with a 200.-Hz tuning fork. The resonant length corresponding to the first harmonic is 42.5 cm. The speed of the sound must be ____.

a. 85.0 m/s

b. 170. m/s

c. 340. m/s

d. 470. m/s

e. 940. m/s

 

49. TRUE or FALSE:

A violinist plays a note whose fundamental frequency is 220 Hz. The third harmonic of that note is 800 Hz.

a. True

b. False

 

50. In order for two sound waves to produce audible beats, it is essential that the two waves have ____.

a. the same amplitude

b. the same frequency

c. the same number of overtones

d. slightly different amplitudes

e. slightly different frequencies

 

 

 51. TRUE or FALSE:

Two tuning forks with frequencies of 256 Hz and 258 Hz are sounded at the same time. Beats are observed; 2 beats will be heard in 2 s.

a. True

b. False

 

52. A tuning fork of frequency 384 Hz is sounded at the same time as a guitar string. Beats are observed; exactly 30 beats are heard in 10.0 s. The frequency of the string in hertz is ____.

a. 38.4

b. 354 or 414

c. 369 or 399

d. 374 or 394

e. 381 or 387

 

Part C: Problem-Solving and Computational Problems

 53. Determine the decibel rating of the following intensities of sound.

  1. I = 1.0 x 10-5 W/m2
  2. I = 1.0 x 10-2 W/m2
  3. I = 6.1 x 10-6 W/m2
  4. I = 2.2 x 10-4 W/m2
  5. A sound which is 4 times more intense than the sound in part d.
  6. A sound which is 7 times more intense than the sound in part d.
  7. A sound which is 10 times more intense than the sound in part d
  8. A sound which is 100 times more intense than the sound in part d.
  9. The sound of an orchestra playing a movement pianissimo at 7.5 x 10-6 W/m2 (very softly)
  10. The sound of an orchestra playing a movement fortissimo at 2.5 x 10-4 W/m2 (very loudly)

 

54. A machine produces a sound with an intensity of 2.9 x 10-3 W/m2. What would be the decibel rating if four of these machines occupy the same room?

 

55. The sound in the United Center during a Chicago Bulls basketball game in 1998 was seven times as intense as it is today. If the decibel rating today is 89 dB, then what was the intensity rating in 1998?

 

56. A sound has an intensity of 8.0 x10-3 W/m2 at a distance of 2.0 m from its source. What is the intensity at a distance of ...

  1. ... 4.0 m from the source?
  2. ... 6.0 m from the source?
  3. ... 8.0 m from the source?
  4. ... 24.0 m from the source?
  5. ... 46.1 m from the source?

 

57. Ben Stupid is sitting 2.0 m in front of the speakers on the stage at the Twisted Brother concert. The decibel rating of the sound heard there is 110 dB. What would be the decibel rating at a location of ...

  1. ... 4.0 m from the speaker?
  2. ... 6.0 m from the speaker?
  3. ... 20.0 m from the speaker?

 

58. Use the Doppler equation for a moving source to calculate the observed frequency for a 250.-Hz source of sound if it is moving with a speed of ____ . (Assume that the speed of sound in air is 340. m/s.)

  1. 30. m/s towards the observer.
  2. 30. m/s away from the observer.
  3. 300. m/s towards the observer.
  4. 300. m/s away from the observer.
  5. 320. m/s towards the observer.
  6. 335 m/s towards the observer.

 

59. Shirley Yackin is holding the phone cord in her hand. It is stretched to a length of 2.4 m and has a mass of 1.8 kg. If the tension in the phone cord is 2.5 N, then determine the speed of vibrations within the cord.

 

60. (Referring to problem #59.) With what frequency must Shirley vibrate the cord up and down in order to produce the second harmonic within the cord?

 

61. (Referring to problem #60.) If Shirley maintains this same frequency and wishes to produce the fourth harmonic, then she will have to alter the speed of the wave by changing the tension. Assuming the same mass density as in #59, and the same frequency as in #60, to what tension must the cord be pulled to produce the fourth harmonic?

 

62. A guitar string has a mass of 32.4 g and a length of 1.12 m. The string is pulled to a tension of 621 N. Determine the speed at which vibrations move within the string.

 

63. (Referring to problem #62.) Stan Dingwaives is playing this guitar. If Stan leaves the string "open" and uses its full length to produce the first harmonic, then what frequency will Stan be playing?

 

64. (Referring to problem #62 and #63.) If Stan wishes to increase the frequency by a factor of 1.2599, then how far (in cm) from the end of the string must he "close" the string (i.e., where must he press his finger down to change the length and produce the desired frequency)? Use the same mass density and speed as in problem #62.

 

65. A guitar string has a fundamental frequency of 262 Hz. Determine the frequency of the ...

  1. ... second harmonic.
  2. ... third harmonic.
  3. ... fifth harmonic.
  4. ... eighth harmonic.

 

66. Determine the speed of sound through air if the temperature is ...

  1. ... 0 degrees Celsius.
  2. ... 12 degrees Celsius.
  3. ... 25 degrees Celsius.
  4. ... 40 degrees Celsius.

 

67. A wind chime is an open-end air column. Determine the fundamental frequencies of a 62.5-cm chime when the temperature is ... .

  1. ... 12 degrees on a cold autumn evening.
  2. ... 25 degrees on a summer evening.
  3. ... 40 degrees during a hot summer day.

 

68. An organ pipe has a length of 2.45 m and is open at both ends. Determine the fundamental frequency of the pipe if the temperature in the room is 25 degrees Celsius.

 

69. (Referring to problem #68.) Determine the fundamental frequency of the pipe if it is closed at one end.

 

70. The auditory canal of the outer ear acts as a closed end resonator which has a natural frequency of around 3500 Hz. This canal serves to amplify sounds with frequencies around this value, thus making us more sensitive to such frequencies. If the speed of waves inside the canal is 350 m/s, then what is the estimated length of the canal?

 

71. Determine the frequency of the lowest three harmonics at which a closed-end air column would sound out at 25 degrees Celsius if its length is 135 cm.

 

72. Suppose that a sound is produced in a helium-filled air column rather than an air-filled air column. By what factor will this change in medium alter the frequency of the sound. (GIVEN: vair = 331 m/s; vHe = 970 m/s)

 

73. An organ pipe is used to produce the lowest note audible to the human ear - 20.-Hz. If the temperature is 25 °C, then how long is the organ pipe? (First decide whether it will produce this low note as a closed- or as an open-end air column.)

 

74. Determine the length of an open-end air column which would produce a 262 Hz frequency on a balmy day when the temperature is 12 degrees.

 

75. A 440.-Hz tuning fork is held above the open end of a water-filled pop bottle and resonance is heard. The length of the pop bottle (bottom to top) is 28.2 cm. If the speed of sound is 345 m/s, then to what height is the pop bottle filled with water?

 

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Questions #1-#9
Questions #10-#52
Questions #53-#64
Questions #65-#75