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SLHS 305 Hearing Sciences > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is sound?

A
  • Vibrations that travel through the air or another medium
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2
Q

What is the source of sound?

A
  • The back and forth motion of a mechanical object around its equilibrium positon
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3
Q

What is the back-and-forth motion called?

A
  • oscillation or vibration
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4
Q

What is the Doppler Effect?

A
  • A change in volume sound!
    1) Static sound source: stationary frequency
    2) Moving sound source: Sound properties change; depending on where you are, you can have a low frequency or higher frequency
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5
Q

What is oscillation?

A
  • Back and forth movement—>DUE TO GRAVITY
  • Pendulum
  • Lunar Tide
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6
Q

What is Vibration?

A
  • Back and forth movement—> DUE TO ELASTICITY
    -Mass and Spring System
  • Tuning fork
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7
Q

What is Pendulum Motion?

A
  • Oscillates back and forth between two states ( Swings)
  • Helps us understand how motion works
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8
Q

Why does the pendulum swing back and forth?

A

-Because of the interaction between inertia and the restoring force of gravity
- When the pendulum moves, energy distribution changes potential–>Kinetic Energy

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9
Q

Why does the pendulum eventually stop?

A
  • Potential Energy—> Kinetic Energy
  • Because of the force of friction
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10
Q

What is a sine function?

A
  • Oscillation made by a pendulum
  • Called a sinusoidal motion( moving back and forth at regular intervals)
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11
Q

What is periodic motion?

A
  • Motion that repeats itself in regular intervals until it is stopped by friction
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12
Q

What is simple harmonic motion?

A
  • Acceleration! The more you pull it one way, the more it will wan tot stay in the other direction
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13
Q

What is waveform?

A
  • A function that represents changes of any physical quantity as a function of time
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14
Q

What is a Cycle?

A
  • a cycle is one full repetition of periodic motion
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15
Q

What is a waveform?

A
  • Number of cycles per second
  • Unit for frequency is hertz( Hz)
    Frequency( f) = Number of Cycles/ Time
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16
Q

What is period?

A

Period(T) is time required for the completion of one cycle of a periodic motion

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17
Q

What is amplitude?

A
  • describes the size of pressure variations ( Distance from equilibrium to the top/bottom of the crest)
  • Measured on the Y axis
  • Related to loudness
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18
Q

How do sound waves move?

A

They move through a medium( Like air) via particle-to-particle interaction

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19
Q

What is the particle-to-particle interaction?

A

1) Particles in space resting
2) Particles create a change of events when they hit each other
3) Creates vibration and transfers energy
4) Energy overtime gets smaller and smaller

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20
Q

What is compression?

A
  • Area where air molecules are bundled up (high pressure)
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21
Q

What are Rarefactions?

A
  • Area where air molecules are more spread apart ( Low pressure )
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22
Q

What is a phase?

A
  • Location of a cycle in wavelength
  • Measured in degrees
  • Max positive magnitude is 90 degrees
  • Max negative magnitude is 270 degrees
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23
Q

What if 2 waves are the same? Different?

A

1)the same—>Amplifies it!
2) Different—> cancel each other out!

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24
Q

What is a phase relationship?

A
  • The difference between phases of two periodic waveforms as they cycle through time
  • Involves in phase/out phase
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25
Q

What is in phase?

A
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26
Q

What is out phase?

A
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27
Q

What does magnitude mean?

A
  • The amount or quantity of something
  • Magnitude of a waveform at at any given moment of time is called the instantaneous magnitude
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28
Q

What is the average magnitude for simple harmonic motion?

A

Zero!

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29
Q

What is a resonance curve?

A
  • Shows the amplitude of vibration as a function of frequency of the driving force
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30
Q

What are the characteristics of a sound wave?

A
  • rarefaction
  • Condensation/compression
  • Wavelength
  • Period
  • Frequency
    -Crest
    -Trough?
    -Amplitude
    -Cycle
    -Phase
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31
Q

true/false: Sound needs a medium to travel

A

True!

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32
Q

What are the different types of mediums?

A

Vacuum, Gas,Liquid,Solid

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33
Q

What do speed and sound depend on?

A

Density and Stiffness( of the medium)

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34
Q

What affects the density and stiffness of the medium?

A

Temperature

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35
Q

True/False: The GREATER the STIFFNESS and the LOWER the DENSITY, the faster the speed of sound

A

TRUE

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36
Q

What does greater stiffness equal?

A
  • Greater stiffness=returns to resting position quickly
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37
Q

What happens as the temperature increases?

A

The density of air decreases

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38
Q

What happens to the speed of sound when temperatures are higher?

A

Sound is faster

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39
Q

What is friction?

A
  • A transfer of energy
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40
Q

What is damped friction?

A
  • Overtime/displacement
    -Gets lower across time: energy decipates really fast
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41
Q

What is a Standing wave?

A
  • A wave that has its reflection come back: Increase of areas enhance, areas cancel out
  • Combination of two waves moving in opposite directions, each having the same amplitude and frequency
    -Vibrations being produced
  • Inhancemnets= louder/more displacement
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42
Q

What is a node?

A
  • Middle point if wave
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43
Q

What is an antinode?

A
  • Greasted amplitude of wave
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44
Q

What creates resonance?

A
  • Standing Wave
45
Q

How does resonance relate to the ear canal?

A
  • Having its own frequency( Natural frequency)
  • WHen driving frequency matches natural frequency
    Thus creating an enhancement of sounds
46
Q

What systems only have one resonance frequency?

A
  • Pendulum
  • Mass and spring
47
Q

True/False, Most vibrating systems have more than one resonance

A

True!

48
Q

What is the resonance curve?

A
  • Shows the amplitude of vibrations as a function of the frequency of the driving force
  • Enhancement in magnitude
  • moving/displacing of a specific frequency
  • Vibration force matches natural frequency
  • Being further away=not as much enhancement
49
Q

What are complex vibrations?

A
  • Combination of two or more sinusoidal
  • Objects commonly vibrate with s complex vibration
50
Q

What is simple sinusoidal vibration?

A
  • Rarely present in nature
  • Pure tones—> 1 frequency component
51
Q

What is the Fourier Theorem?

A
  • Any complex vibration is the sum of various sinusoidal motions of varying amplitude, frequency, and phase
  • Complex vibration that you separate/break down
  • Simple waves with frequency
52
Q

What is periodic vibration?

A
  • Complex waves
  • Shows rhythm and pattern
53
Q

What is Aperiodic vibration?

A
  • Complex waves
  • No rhythm is shown
    -lots of frequency
    -no pattern
  • Motion is random( This is called noise)
54
Q

What is a fundamental period?

A
  • The duration of one cycle
  • Pitch we perceive
    : Number of harmonics that can be divided by
55
Q

What is waveform synthesis?

A
  • Combination of several individual sinusoidal motions into a complex waveform
56
Q

What does being harmonically related mean?

A
  • When components of a complex wave form are whole number multiples of the f0
  • Components are called harmonics
57
Q

What are harmonics?

A

A mode of vibration is the specific vibration pattern of a vibrating system associated with each resonance frequency of the system

58
Q

First mode of vibration?

A

First harmonic!

59
Q

Second mode of vibration?

A
  • Second harmonic!
  • Equal to two times the fundamental
60
Q

Third mode of vibration?

A
  • Third harmonic!
  • Equal tp three times the fundamental
61
Q

Where can you find the most displacement?

A
  • In the antinode
62
Q

Where can you find the point of destruction?

A

Node
- Waves cancel out

63
Q

What is a common factor?

A
  • An integer that can be divided into a number with no remainder
64
Q

What is the greatest common factor?

A
  • the largest of the common factors
  • Number that can be divided evenly, no fractions
65
Q

What is an octave?

A

The doubling of frequency

66
Q

What is a missing fundamental?

A

When the fundamental frequency is not equal to the frequency of its lowest component

67
Q

What is a complex periodic wave?

A

When frequency components are harmonically related( all components are whole number multiples of f0)

68
Q

What is waveform analysis?

A

Breaking down complex waveforms and determining its components
Shows us the frequency domain of the vibration
Spectral Components are displayed as verticle lines

69
Q

What is a spectrum?

A
  • A graph used to show the amplitude of the components
  • X-axis: Frequency ( Hz)
  • Y axis: Amplitude
70
Q

What is a complex aperiodic vibration?

A
  • No pattern to waveform
  • many different components that do not appear as separate lines on the spectrum
71
Q

what is a line spectrum?

A
  • Consisting of one or more separate verticle lines
72
Q

What is a continuous spectrum?

A

When a spectrum has many spectral components

73
Q

Where would sound travel the fastest?

A

In a Solid

74
Q

What does stiffness mean?

A

In acoustics, it is elasticity; the ability of vibrating objects to return to its original position

75
Q

What are the two most common types of modulus of elasticity?

A
  • The bulk module of elasticity for fluids and gases
  • Young’s modulus of elasticity for solids
76
Q

What does sound pressure indicate?

A
  • Indicates how compressed or rarefied the particles are
77
Q

What does sound intensity indicate?

A
  • Indicates how much sound power is transferred from the sound source to the surrounding area
78
Q

Infrasound?

A
  • Sounds of very low frequency that cannot be hear( typically below 20Hz)
79
Q

Sound( audible sound)

A
  • Sounds of frequencies that can be heard( typically in 20Hz to 20,000 Hz range for humans)
80
Q

Ultrasound?

A

Sounds of very high frequencies that cannot be heard( Typically above 20kHz)

81
Q

What is impulse noise?

A
  • Single brief event caused by a sudden change in a sound source
    EXAMPLE: Delay and decay—> a gunshot can cause hearing loss if you are too close to the sound
81
Q

What is impulse noise?

A
  • Single brief event caused by a sudden change in a sound source
    EXAMPLE: Delay and decay—> a gunshot can cause hearing loss if you are too close to the sound
82
Q

What is continuous noise?

A
  • Continues for a period of time and is made up of a large number of random acoustic events connected together
  • Can be divided into two categories:
    1) Nonstationary Noise
    2) Stationary Noise
83
Q

What is a power spectrum density function?

A

The average amount of sound power across all of the frequencies of the sound

84
Q

Absorption:

A
  • feature that sound engineers/musicians think about
  • Absorbed because of the characteristics of the wall, ceiling, floor, etc.
  • Volume can be different because some sound is absorbed and sound can be reflected back
85
Q

Absorption Example:

A
  • Think about an ocean wave;
    ocean waves can be observed by the dirt
    reflected back means it won’t have the same energy as before
86
Q

Does the absorption coefficient vary?

A
  • Varies from 0 to 1
  • Depends on the frequency of the sound wave ( high? or low? between?)
  • Depends on the properties of the boundary( wall?)
87
Q

What absorbs more sound energy?

A
  • Soft material!
    Ex: carpet, drapes, upholstered furniture)
88
Q

Absorption coefficient:

A
  • usually increases with sound frequency
  • Sometimes absorption is higher for low frequency sounds
89
Q

Absorption coefficient:

A
  • usually increases with sound frequency
  • Sometimes absorption is higher for low frequency sounds
90
Q

What is the reflection coefficient?

A
  • reflected property of a boundary
  • Varies from 0-1
    Depends on:
    1) frequency of the arriving sound wave
    2)properties of the boundary medium
91
Q

What happens to all of the energy arriving at a boundary?

A
  • It is either absorbed or reflected so that the total sound intensity must equal the sum of the two
92
Q

Sound absorption and reflection are important for the construction of:

A
  • Concert halls
  • Classrooms
  • Hospitals
  • Libraries
93
Q

What happens during refraction?

A

As sound enters a new medium:
1) frequency remains the same BUT
2) the wavelength and direction change because the speed of sound changes

94
Q

What is sound refraction?

A
  • The bending of sound waves ( change in direction) when the sound enters a medium with a different density or stiffness
95
Q

Sound refraction in the air?

A
  • Since the speed of sound in warmer air is greater than the speed of sound in cooler air, sound waves bend towards the cooler air
  • Sound arrives from different angles/directions( reflected/refracted)*
96
Q

What is Reverberation?

A
  • When you hear a sound persist after the sound is gone( sound is continuing to play)
  • Large space+highly reflective walls= a lot of reverberation
  • Small Spaces+absorbing material= very little reverberation
97
Q

What is reverberation time?

A
  • The time it takes for a brief sound to decrease in sound pressure by 60dB
  • Depends on the volume size of the room and the absorption provided by the boundaries of the room
98
Q

What is diffraction?

A

Sound waves bending around objects and through openings in boundaries
Sound bending through energy

99
Q

What is an acoustic shadow?

A
  • An area in which sound waves do not enter or in which the sound intensity is decreased ( or does not exist)
100
Q

What are beats?

A
  • Changes in waves caused when two sine waves that are very close in frequency interfere with one another
  • They occur because of the periodically changing phase relationship between two pure tones
101
Q

What is the Doppler effect?

A
  • When the sound source moves toward the listener, the wavelength of sound in the medium is affected and it gets shorter
102
Q

What does the absolute difference tell us?

A
  • Tells us how much greater one measurement is than another. This involves subtraction
    EXAMPLE: My child has grown 4” in the past month
103
Q

What does the relative difference tell us?

A

Tells us how many times greater one measurement is than another
EXAMPLE: Mississippi is twice as large as west Virginia

104
Q

Treu/False: An octave is a doubling in frequency

A

true! 200Hz? next octave will be 400Hz

105
Q

Why do we use a logarithmic scale?

A

it compresses a large range of power magnitudes into a much smaller range
- easier range/reasonable

106
Q

Why is the decibel scale used?

A
  • Correlates with human perception
  • Compresses a large range of values to a much smaller/manageable range
    -Supports decimal notation by using the base 10 logarithm
107
Q

Clicker Question: What is the sound pressure level of a balloon popped at your ear?

A

155 dB SPL

SLHS 305 Hearing Sciences (3 decks)

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