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1

Length or distance of a single cycle

Wavelength

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2

Unit for wavelength

Millimeters

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3

Typical values for wavelength

.1-.8mm

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4

Wavelength is determined by

Sound source and medium

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5

Can wavelength be changed by sonographer

No

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6

How are wavelength and frequency related

Inversely

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7

Higher frequency=

Shorter wavelengths

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8

Lower frequency=

Higher wavelengths

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9

The rate that sound travels through medium

Propagation speed or speed of sound

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10

Propagation speed units

Distance/time Mm/no

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11

Typical value for propagation speed

1500-1600 meters per second

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12

What is propagation determined by

Medium only

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13

Can propagation speed by changed by sonographer

No

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14

Air

330m/s

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15

Lung

500m/s

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16

Fat

1450 m/s

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17

Soft tissue (average)

1,540m/s

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18

Liver

1,550m/s

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19

Kidney

1560m/s

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20

Blood

1570m/s

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21

Muscle

1600m/s

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22

Tendon

1850m/s

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23

Bone

3500m/s (2000-4000)

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24

How are speed and wavelength related (7)

Directly related (7)

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25

Sound in slow medium has ______ wavelength

Short

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26

Sound in fast medium has _____ wavelength

Long

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27

Two characteristics of medium that affect the speed of sound

Stiffness Density

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28

How are density and speed related (8)

Inversely related (8)

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29

Change in shape, ability of an object to resist compression

Stiffness

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30

Describes the relative weight of a material

Density

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31

Can make the biggest change

Stiffness

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32

What can have the greatest effect on speed

Stiffness

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33

What relationship does speed and stiffness have

Direct

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34

Other words for density

Compressibility Density Elasticity

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35

Bulks relationship with speed

Direct (not the same as stiffness but has the same effect on speed)

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36

If stiffer=

Goes faster

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37

If denser=

Goes slower

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38

The higher the frequency=

The less penetration

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39

Amplitude =

Squared

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40

If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times (True or false)

False would be 9

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41

Does propagation do anything to frequency

No

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42

Acoustic variables

Density Particle motion Pressure (Pretty dang dumb)

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43

What will create the fastest speed of sound

Low density, high stiffness

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44

When two waves overlap at the same location and at the same instant in time, they combine with each other. The result of overlap is the creation of a single, new wave

Interference

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45

In phase

Constructive interference

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46

Out of phase

Destructive interference

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47

When peaks and troughs come together opposite times they cancel out and make a smaller wave

Destructive

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48

When the amplitude is less than one of the original two waves

Out of phase

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49

Any number represents the number "10s" that are multiplied together to create the original number

Logarithms

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50

Comparing a new intensity to original

Logarithmic scale

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51

Log of 100

2

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52

Log of 1000

3

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53

_____dB means two

3

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54

The final intensity is twice as big as the original intensity

3dB

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55

The final intensity is 4 times the original

6dB

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56

The final intensity is 8 times the original

9dB

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57

The final intensity is 10 times bigger than the original intensity

10dB

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58

The final intensity is 100 times bigger than the original

20dB

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59

If using negative number new intensity will be _______ than original

Smaller

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60

Fallen to 1/2 the original value

-3dB

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61

Means we have fallen to 1/4 original intensity

-6dB

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62

Means we have fallen to 1/8 of the original value

-9dB

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63

We have fallen to 1/10 of the original value

-10dB

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64

We have fallen to 1/100 of the original value

-20dB

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65

How many intensities do we need to calculate decibels

2 intensities

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66

A single power increases from 1 watt to 100 watts. How is this expressed in decibels?

20dB

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67

An ultrasound system is operating at 100% power and the power setting is 0dB. What would the power setting be when the system is operating at 50%

-3dB

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68

A sound beam has increased from its initial intensity by a factor of 100. How is this described in decibel notation?

20dB

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69

DB is a mathematical representation with a _______ scale

Logarithmic

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70

The relative CHANGE in a sound beams intensity is measured in

Db

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71

Intensity unit

Watts/cm^2

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72

The decrease in intensity, power, and amplitude as sound travels

Attenuation

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73

Further sound travels the ________ it gets

Weaker

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74

Attenuation units

DB

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75

Frequency and attenuation have what relationship (5)

Direct (5

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76

Path length and attenuation have what relationship (3)

Direct (3)

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77

Higher the frequency the ________ attenuation

More

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78

More frequency travels _________ they attenuate

More

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79

High frequency =

More attenuation Long pathway

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80

For less attenuation you want

Short pathway Low frequency

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81

For more attenuation you want

High frequency Long pathway

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82

A 3MHz sound beam travels through two media. It attenuates 5dB in medium A and 6 dB in medium B. What is the total attenuation that sound beam undergoes as it travels through both media

11dB

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83

3 processes that contribute to attenuation

Reflection Scattering Absorption

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84

Sound dissipated in heat

Absorption

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85

As sound strikes a boundary, a portion of the wave's energy may be redirected, or reflected, back to the sound source

Reflection

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86

2 types of reflection

Specular & Diffuse

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87

Back scatter

Diffuse

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88

Reflectors form a smooth reflector (mirror) are specular and return in ONE direction

Specular

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89

Occurs when the wavelength is much smaller than the irregularities in the boundary

Specular reflection

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90

When are specular reflectors well seen

When the sound wave strikes the reflector at 90 degrees

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91

Examples of specular boundaries

Diaphragm Walls of vessels

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92

What is best for grey scale

90

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93

When boundary is rough, reflected sound is disorganized and random (1)

Diffuse reflection (1)

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94

Occurs when the boundary has irregularities that are approximately the same size as the sound's wavelength (6)

Diffuse reflection (6)

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95

The distribution of sound randomly in all directions

Scattering

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96

When does sound scatter

When the tissue interface is small; that is, equal to or less than the wavelength of the incident sound beam

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97

Which sound beams scatter more

High frequency

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98

If reflector is much smaller or wavelength is bigger

Raleigh scattering

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99

Omni directional

Raleigh scattering

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100

Rayleigh and frequency relationship

Proportional

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