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Ultrasound physics > Chapter 2 - Sound > Flashcards

Chapter 2 - Sound Flashcards

1
Q

The effects of the sound wave upon the biological tissue is called____?
❤️

A

Biologic effects

❤️

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2
Q

Sound is a type of wave that carries ____ , from place to place.
❤️

A

ENERGY ❤️

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3
Q

Sound is series of ____ and ____

❤️

A

Compressions and rarefactions

❤️

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4
Q

Areas of increased pressure and density are called ____?

A

Compressions

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5
Q

areas of decreased pressure and density are called ____?

A

Rarefactions

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6
Q

Sound must travel through a _____

A

Medium

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7
Q

Sound cannot travel through a _____

A

Vacuum

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8
Q

What type of waves is sound made of???

A

Mechanical and longitudinal

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9
Q

Sound travels in a _____ line

A

Straight

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10
Q

_____ ______ IDENTIFY which waves are sound waves

A

Acoustic variables

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11
Q

When an _____ _____ changes rhythmically in time, a _____ _____ is present.

A

Acoustic variable

sound wave

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12
Q

What are the 3 acoustic variables?

A

Pressure ❤️

Density

Distance

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13
Q

____ is this concentration of force within an area,

Force/area❤️

A

Pressure

Units: pascals (Pa) ❤️

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14
Q

____ is the concentration of mass within a volume

A

Density

Units: kg/cm^3

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15
Q

_____ measure of particle motion

A

Distance

Units: cm,feet & miles

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16
Q

What are the two types of waves?

A

Transverse and longitudinal

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17
Q

_____ ______ : particles move in a perpendicular direction to the direction of the wave

A

Transverse waves

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18
Q

_____ _____ : particles move in the same direction as the wave

A

Longitudinal

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19
Q

Regions of higher density and pressure are called ______

A

Compressions

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20
Q

Regions of lower density and pressure are called _____

A

Rarefactions

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21
Q

Acoustic _____ inform us of which waves are sound

A

Variables

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22
Q

Acoustic _____ describe the features of a particular sound wave

A

Parameters

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23
Q

Name the seven acoustic parameters

A 
Period 
Frequency 
Amplitude 
Power
Intensity 
Wavelength 
Speed
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24
Q

The time required to complete a SINGLE cycle is called a _____

Or aka as the time from start of a cycle to the start of the next cycle

A

Period

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25
Q

The typical values for a Period is _____

A

0.06 to 0.5 ùsecond (less than 1-millionth of a second)

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26
Q

A period is determined by _____

A

Sound source

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27
Q

Number of CERTAIN EVENTS that occur in a particular time

A

Frequency

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28
Q

What are the units for frequency?

A

Per second , 1/sec, Hertz, Hz

Hertz is Just another way of saying per second

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29
Q

What are the typical values for frequency???

A

2 MHz to 15MHz

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30
Q

Frequency affects ___ and _____

A

Penetration and axial resolution (image quality)

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31
Q

A wave exceeding 20,000Hz (20 kHz)

A

Ultrasound

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32
Q

____ this frequency is so HIGH that it cannot be heard by man

A

Ultrasound

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33
Q

Frequencies between 20Hz and 20,000Hz

A

Audible sound

Heard by man

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34
Q

Sound with frequencies less than 20Hz

A

Infrasound

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35
Q

This sound wave cannot be heard by man because it is so LOW

A

Infrasound

Less than 20Hz

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36
Q

_____ and ____ are related to each other, they are RECIPRICOALS

A

Frequency and period

37
Q

The complimentary unit for sec is _____

A

Hz

38
Q

The rate that which work is performed or the rate of energy transfer

A

Power

39
Q

What is the unit for power?

A

Watts

40
Q

Power _____ as sound propagates through the body

A

Decreases

41
Q

Power is ______ to the waves amplitude squared

A

Proportional

42
Q

If amplitude is doubled, the power is increased by a factor of _____?

A

Four (quadrupled)

2x2=4

43
Q

The concentration of energy in a sound BEAM

A

Intensity

44
Q

The beams power divided by the beams cross sectional area is called

A

Intensity

45
Q

Equation for intensity

A

Watts/cm^2

Power(watts)/ beam area (cm^2)

46
Q

Intensity ____ as sound propagates through the body

A

Decreases

47
Q

What type of relationship does intensity and POWER have?

A

Direct
Proportional
When one goes up the other goes up

48
Q

What type of relationship does intensity and AMPLITUDE have?

A

Proportional

Direct

49
Q

Intensity is proportional to the amplitude of the wave ____

A

SQUARED

50
Q

Intensity is proportional to the _____ of the wave squared

A

Amplitude

51
Q

The effects of the medium upon the sound wave is called ____ ?
❤️

A

Acoustic propagation properties

❤️

52
Q

If the AMPLITUDE is doubled, the intensity is increased by a factor of _____

A

Four

2x2=4

53
Q

If amplitude is quartered, the intensity is reduced by a factor of _____

A

16

(1/4)^2 = 1/4 x 1/4 = 1/16

54
Q

What is the definition of wavelength?

A

The length or distance of a single cycle.

55
Q

What are the units used for wavelength?

A

Meters
Mm
Or any unit of LENGTH

56
Q

Wavelength is the _____ or _____ of a single cycle.

A

Length or distance

57
Q

Wavelength is determined by ______?

A

BOTH the source and the medium

58
Q

Can wavelength be changed by the sonographer?

A

No

59
Q

What is the equation for wavelength?

A

Wavelength (mm) = propagation speed (mm/ùs) / frequency (MHz)

Or

L = C/F

60
Q

HIGHER frequency waves have _____ wavelengths.

A

Shorter

61
Q

LOWER frequency waves have _____ longer wavelength.

A

Longer

62
Q

In what type of tissue does sound have a frequency of 1MHz, with a wavelength of 1.54mm?

A

Soft tissue

63
Q

In soft tissue, sound has a frequency of ____ has a wavelength of _____ ?

A

1 MHz and 1.54mm

64
Q

In soft tissue you divide 1.54mm by ____ in MHz

A

Frequency

65
Q

The rate that sound travels through a medium

A

Propagation speed

66
Q

What’s another name for propagation speed?

A

Velocity or speed

67
Q

Units used for propagation speed?

A

Meters per second

Mm/ùs

68
Q

Propagation is determined by what?

A

Medium only - density and stiffness

All sound travels through the same speed through any specific medium.

Ex. Frequencies of 5mhz and 3mhz travel at the same speed through the same medium.

69
Q

What is the average speed of all sound ( regardless of frequency) in biological or soft tissue?

A

1,540 m/s

  1. 540 km/s
  2. 54 mm/ùs
70
Q

Lung (air) is less than _____ and ____

A

Fat, soft tissue and bone

71
Q

Sound in a _____ medium has a short wavelength

A

Slow

72
Q

Sound in a _____ medium has a long wavelength

A

Fast

73
Q

The tissue type of air has a speed (m/s) of?

A

330 m/s

74
Q

The tissue type of lung has a speed of

A

300-1,200 m/s

75
Q

The tissue type of fat has a speed of

A

1,450m/s

76
Q

The tissue type for soft tissue and blood has a speed of

A

1,540

77
Q

The tissue type for tendon has a speed of

A

About 1,850 m/s

78
Q

The tissue type of bone has a speed of

A

2,000-4,000 m/s

79
Q

Stiffness and speed move in the ______ direction.

A

Same

80
Q

Density and speed move in ______ directions.

A

Opposite

81
Q

Bulk modules is the same as _____

A

Stiffness

82
Q

Stiffness is related to change in _______

A

Shape “squishability”

83
Q

Density is related to ______

A

Weight

84
Q

When two waves overlap at the same location and at the same time, they combine into a single new wave.

A

Interference

85
Q

Occurs when the amplitude of the new, combined wave is greater than the original two waves.

A

Constructive interference

86
Q

What type of phase interferes constructively?

A

In-phase waves

87
Q

The amplitude of the new wave is less than one of the original waves.

A

Destructive interference

88
Q

What type of phase interfere destructively?

A

Out-of-phase waves

Ultrasound physics (3 decks)

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