PS 222: Final Exam quizzes with
complete reviewed solutions
Sound is initiated by movement that disturbs air molecules.
Molecules collide with other air molecules resulting in air pressure that propagates outward
from source.
As the sound wave travels outward from the source in all directions, the wave front resembles a
sphere that grows continuously larger,
Sound energy at any given point on the wave front decreases with distance from the source
(inverse square law). - answer ✔✔-how does sound work?
sound waves - answer ✔✔-Waves of pressure changes in air caused by the vibrations of a
source
cycle - answer ✔✔-In a sound wave, a repeating segment of air pressure changes
FIGURE 10.1
Consider four small volumes of air (A-D) to the right of a tuning fork. When the fork is struck at
Time 1, the tine pushes against the air molecules to its right, forcing them over and initiating a
chain of collisions to the right in volume A, with the result that for a brief time all the air
molecules there are compressed closer together, increasing the air pressure within volume A.
At Time 2, the vibrating tine has moved back to the left, beyond its initial position, making
volume A bigger and resulting in rarefaction, a less-than-normal air pressure in volume A. At the
same time, the effects of the initial collisions in volume A have been transmitted into volume B,
resulting in compression there. Mirroring the vibrations of the tuning fork, this succession of
,compressions and rarefactions propagates outward in all directions. - answer ✔✔-explain how a
air molecules are disturbed in sound
FIGURE 10.2
One cycle fork set up regularly varying cycles of increasing and decreasing air pressure at a point
just to the right of the fork, as illustrated by the cycles of compression and rarefaction (high and
low air pressure) in volume A in this figure.
One cycle is a repeating portion of the wave, shown here as a portion during which the wave
varies from normal air pressure to a maximum, then to a minimum, and then back to normal. -
answer ✔✔-explain a cycle
frequency, amplitude, waveform - answer ✔✔-the three most important physical dimensions of
sound
pitch, loudness, timbre - answer ✔✔-perceptual dimensions of frequency, amplitude, and
waveform
acoustic energy - answer ✔✔-Just as wavelengths for electromagnetic energy, there are
wavelengths of
Although researchers often use pure tones called periodic sound waves, most sounds heard are
composed of many different pure or aperiodic tones. Pure tones are the result of a sinusoidal or
sine wave. - answer ✔✔-are most sounds like pure tones?
sinusoidal/sine wave - answer ✔✔-pure tones are the result of a
hertz - answer ✔✔-unit of measurement of frequency
decibel - answer ✔✔-unit of measurement of amplitude
,none - answer ✔✔-unit of measurement of waveform
periodic sound wave - answer ✔✔-Waves in which the cycles of compression and rarefaction
repeat in a regular, or periodic, fashion.
compression - answer ✔✔-a region in a longitudinal wave where the particles are closest
together
rarefaction - answer ✔✔-a region in a longitudinal wave where the particles are furthest apart.
sound waves - answer ✔✔-traveling vibrations of air that consist of regions of high pressure
caused by compression of air molecules alternating with regions of low pressure caused by
rarefaction of the molecules.
Sound energy is gradually dissipated as sound waves travel farther from the original source. The
intensity of the sound decreases, until it finally dies out when the last sound wave is too weak
to disturb the air molecules around it. - answer ✔✔-how does sound energy dissipate?
pure tone - answer ✔✔-Sound wave in which air pressure changes over time according to a
mathematical formula called a sine wave, or sinusoid
hertz - answer ✔✔-Number of cycles per second of a sound wave; the physical unit used to
measure frequency
frequency - answer ✔✔-of a pure tone is the physical dimension related to the perceptual
dimension of pitch and expressed in hertz (Hz).
, Young human adult sound detection range: About 20 to 20,000 Hz. - answer ✔✔-what
frequencies can we detect?
The loudest sounds a human can hear are approximately 1 million times the amplitude of the
softest sounds that can be heard. - answer ✔✔-how loud are the loudest sounds that we can
hear?
pitch - answer ✔✔-Perceptual dimension of sound that corresponds to the physical dimension
of frequency; the perceived highness or lowness of a sound
amplitude - answer ✔✔-Difference between the maximum and minimum sound pressure in a
sound wave; the physical dimension of sound that is related to the perceptual dimension of
loudness
loudness - answer ✔✔-Perceptual dimension of sound that is related to the physical dimension
of amplitude; how intense or quiet a sound seems
decibels - answer ✔✔-: Physical unit used to measure sound amplitude; logarithmically related
to sound pressure measured in micropascals
loudness - answer ✔✔-Physical dimension of amplitude is related to perceptual dimension of
amplitude - answer ✔✔-Difference between the maximum and minimum sound pressure in a
sound wave; the physical dimension of sound that is related to the perceptual dimension of
loudness; expressed in decibels (dB)
as dB SPL = 20 log(p/p0) - answer ✔✔-Amplitude (or peak amplitude) of a sound in decibels
expressed as
complete reviewed solutions
Sound is initiated by movement that disturbs air molecules.
Molecules collide with other air molecules resulting in air pressure that propagates outward
from source.
As the sound wave travels outward from the source in all directions, the wave front resembles a
sphere that grows continuously larger,
Sound energy at any given point on the wave front decreases with distance from the source
(inverse square law). - answer ✔✔-how does sound work?
sound waves - answer ✔✔-Waves of pressure changes in air caused by the vibrations of a
source
cycle - answer ✔✔-In a sound wave, a repeating segment of air pressure changes
FIGURE 10.1
Consider four small volumes of air (A-D) to the right of a tuning fork. When the fork is struck at
Time 1, the tine pushes against the air molecules to its right, forcing them over and initiating a
chain of collisions to the right in volume A, with the result that for a brief time all the air
molecules there are compressed closer together, increasing the air pressure within volume A.
At Time 2, the vibrating tine has moved back to the left, beyond its initial position, making
volume A bigger and resulting in rarefaction, a less-than-normal air pressure in volume A. At the
same time, the effects of the initial collisions in volume A have been transmitted into volume B,
resulting in compression there. Mirroring the vibrations of the tuning fork, this succession of
,compressions and rarefactions propagates outward in all directions. - answer ✔✔-explain how a
air molecules are disturbed in sound
FIGURE 10.2
One cycle fork set up regularly varying cycles of increasing and decreasing air pressure at a point
just to the right of the fork, as illustrated by the cycles of compression and rarefaction (high and
low air pressure) in volume A in this figure.
One cycle is a repeating portion of the wave, shown here as a portion during which the wave
varies from normal air pressure to a maximum, then to a minimum, and then back to normal. -
answer ✔✔-explain a cycle
frequency, amplitude, waveform - answer ✔✔-the three most important physical dimensions of
sound
pitch, loudness, timbre - answer ✔✔-perceptual dimensions of frequency, amplitude, and
waveform
acoustic energy - answer ✔✔-Just as wavelengths for electromagnetic energy, there are
wavelengths of
Although researchers often use pure tones called periodic sound waves, most sounds heard are
composed of many different pure or aperiodic tones. Pure tones are the result of a sinusoidal or
sine wave. - answer ✔✔-are most sounds like pure tones?
sinusoidal/sine wave - answer ✔✔-pure tones are the result of a
hertz - answer ✔✔-unit of measurement of frequency
decibel - answer ✔✔-unit of measurement of amplitude
,none - answer ✔✔-unit of measurement of waveform
periodic sound wave - answer ✔✔-Waves in which the cycles of compression and rarefaction
repeat in a regular, or periodic, fashion.
compression - answer ✔✔-a region in a longitudinal wave where the particles are closest
together
rarefaction - answer ✔✔-a region in a longitudinal wave where the particles are furthest apart.
sound waves - answer ✔✔-traveling vibrations of air that consist of regions of high pressure
caused by compression of air molecules alternating with regions of low pressure caused by
rarefaction of the molecules.
Sound energy is gradually dissipated as sound waves travel farther from the original source. The
intensity of the sound decreases, until it finally dies out when the last sound wave is too weak
to disturb the air molecules around it. - answer ✔✔-how does sound energy dissipate?
pure tone - answer ✔✔-Sound wave in which air pressure changes over time according to a
mathematical formula called a sine wave, or sinusoid
hertz - answer ✔✔-Number of cycles per second of a sound wave; the physical unit used to
measure frequency
frequency - answer ✔✔-of a pure tone is the physical dimension related to the perceptual
dimension of pitch and expressed in hertz (Hz).
, Young human adult sound detection range: About 20 to 20,000 Hz. - answer ✔✔-what
frequencies can we detect?
The loudest sounds a human can hear are approximately 1 million times the amplitude of the
softest sounds that can be heard. - answer ✔✔-how loud are the loudest sounds that we can
hear?
pitch - answer ✔✔-Perceptual dimension of sound that corresponds to the physical dimension
of frequency; the perceived highness or lowness of a sound
amplitude - answer ✔✔-Difference between the maximum and minimum sound pressure in a
sound wave; the physical dimension of sound that is related to the perceptual dimension of
loudness
loudness - answer ✔✔-Perceptual dimension of sound that is related to the physical dimension
of amplitude; how intense or quiet a sound seems
decibels - answer ✔✔-: Physical unit used to measure sound amplitude; logarithmically related
to sound pressure measured in micropascals
loudness - answer ✔✔-Physical dimension of amplitude is related to perceptual dimension of
amplitude - answer ✔✔-Difference between the maximum and minimum sound pressure in a
sound wave; the physical dimension of sound that is related to the perceptual dimension of
loudness; expressed in decibels (dB)
as dB SPL = 20 log(p/p0) - answer ✔✔-Amplitude (or peak amplitude) of a sound in decibels
expressed as
