Ch. 3 - Describing Sound Waves

Question 0

Wavelength is determined by what?

Answer 0

SS and medium

Question 1

Period and frequency are determined by what?

Answer 1

SS

Question 2

Amplitude, power, and intensity are determined by what?

Answer 2

SS

Question 3

Speed is determined by what?

Answer 3

Medium

Question 4

Which/what acoustic parameter(s) is/are determined by medium only?

Answer 4

Speed

Question 5

Which/what acoustic parameter(s) is/are determined by SS only?

Answer 5

Period, Frequency

Amplitude, Power, and Intensity

Question 6

Which/what acoustic parameter(s) is/are determined by SS and medium?

Answer 6

Wavelength

Question 7

The time required to complete a single cycle is

Answer 7

Period

Question 8

Give an example of period.

Answer 8

The period of class in hs is 50 minutes.

Question 9

Can period be changed by the sonographer?

Answer 9

No

Question 10

Period is determined by what?

Answer 10

SS

Question 11

Typical values of a period are

Answer 11

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

Question 12

Frequency is defined as

Answer 12

Number of certain events that occur during a particular time period.

Question 13

Give an example of frequency

Answer 13

The frequency of presidential elections is once per four years

Question 14

In US, the frequency of a wave is…

Answer 14

the number of cycles of an acoustic variable that occur in one second.

Question 15

The unit for frequency is

Answer 15

Hertz (meaning “per second”)

Question 16

Can frequency be changed by the sonographer?

Answer 16

No

Question 17

What are the typical values of frequency?

Answer 17

2 MHz - 15 MHz

Question 18

What does frequency affect in Us?

Answer 18

Penetration and axial resolution

Question 19

A wave with a frequency exceeding 20,000Hz (so high it isn’t audible) is

Answer 19

Ultrasound

Question 20

Sound heard by man between 20Hz and 20,000Hz

Answer 20

Audible sound

Question 21

Sound with frequencies less than 20Hz are _____. And can they be heard by man?

Answer 21

Infrasound. No, so low it is inaudible.

Question 22

Frequency and ______ are reciprocals.

Answer 22

Period

Question 23

Frequency and period have a(n) _____ relationship.

Answer 23

Inverse

Question 24

With frequency and period, units to be used are (2 examples)

Answer 24

Sec and Hz or microseconds and MHz

Question 25

When period increases, frequency _________.

Answer 25

Decreases

Question 26

What are the 3 bigness parameters (define and list)?

Answer 26

3 parameters that describe a sound wave. Amplitude Power Intensity

Question 27

What is defined as the difference between the average value and the max value of an acoustic variable?

Answer 27

Amplitude

Question 28

List the 3 acoustic variables and their units.

Answer 28

Pressure - Pascals Density - grams/cubic cm Particle motion - m/s, mm/microsecond

Question 29

The unit for amplitude is

Answer 29

Acoustic variables Pressure - Pascals Density - grams/cm^3 Particle motion - cm, m, distance (And Decibels (dB))

Question 30

Can amplitude be changed by the sonographer?

Answer 30

Yes

Question 31

Amplitude ________(increases/decreases) as sound propagates through the body.

Answer 31

Decreases

Question 32

The difference between max and min values of an acoustic variable is called

Answer 32

Peak-to-peak amplitude

Question 33

Amplitude is ______ (fraction) of the peak-to-peak amplitude.

Answer 33

Half

Question 34

The rate of work performed, or the rate of energy transfer is

Answer 34

Power

Question 35

What is the unit for power?

Answer 35

Watts

Question 36

Can power be changed by the sonographer?

Answer 36

Yes

Question 37

Power ______(increases/decreases) as it propagates through the body.

Answer 37

Decreases

Question 38

Why are power and amplitude often described similarly?

Answer 38

Because they both describe "bigness"

Question 39

What is the relationship between power and amplitude?

Answer 39

Power is proportional to the wave's amplitude squared

Question 40

If the amplitude is tripled, the power is

Answer 40

Increased by a factor of 9

Question 41

The concentration of energy in a sound beam is the definition of what?

Answer 41

Intensity

Question 42

The beam's power divided by the beam's cross-sectional area is another description of what?

Answer 42

Intensity

Question 43

Power (watts) _____________ Beam area (cm^2) is an equation for what?

Answer 43

Intensity

Question 44

What is the unit for intensity?

Answer 44

Watts/cm^2

Question 45

Can intensity be changed by the sonographer?

Answer 45

Yes | Since amplitude and power can be changed, the intensity can too

Question 46

Intensity _____ (increases/decreases) as sound propagates through the body.

Answer 46

Decreases

Question 47

What is the relationship between intensity and power?

Answer 47

Proportional or directly-related

Question 48

Intensity is proportional to the _______ of the wave _(value)_.

Answer 48

Amplitude Squared

Question 49

If amplitude is doubled, the intensity is

Answer 49

Increased by a factor of 4 | 2 x 2 = 4

Question 50

The length or distance of a single cycle is

Answer 50

Wavelength

Question 51

This is similar to a boxcar in a long train

Answer 51

Wavelength

Question 52

What is wavelength determined by?

Answer 52

SS and the medium

Question 53

Can wavelength be changed by the sonographer?

Answer 53

No

Question 54

What does wavelength influence in an US?

Answer 54

Axial resolution (image quality)

Question 55

What are the typical values of a wavelength?

Answer 55

0.1 - 0.8mm

Question 56

What is this equation of? Propagation speed (mm/microseconds) ____________________________________ Frequency (MHz)

Answer 56

Wavelength

Question 57

What are the units for wavelength?

Answer 57

m, mm, or any measurement of length

Question 58

Do higher frequency waves have longer OR shorter wavelengths?

Answer 58

Shorter

Question 59

Do high frequency wavelengths have longer OR shorter periods?

Answer 59

Shorter

Question 60

In soft tissue, sound with a frequency of 1 MHz has a wavelength of _____. In soft tissue, sound with a frequency of 2 MHz has a wavelength of _____.

Answer 60

1. 54mm | 0. 77mm

Question 61

This equation is for what? 1.54mm/microsecond ____________________ Frequency (MHz)

Answer 61

Wavelength

Question 62

The rate of sound travels through a medium is a definition for what? What is it also called?

Answer 62

Propagation speed Velocity or speed

Question 63

What are the units for propagation speed?

Answer 63

m/s or mm/microsecond

Question 64

Propogation speed is determined by what?

Answer 64

Medium - density and stiffness

Question 65

Can propagation speed be changed by a sonographer?

Answer 65

No

Question 66

What are the typical values for propagation speed?

Answer 66

Average speed of sound in biologic tissue. | 1,540m/s = 1.54km/s = 1.54mm/microseconds

Question 67

Lung, fat, soft tissue (incl. blood), air, bone, tendon - put these in order of slowest to fastest speed.

Answer 67

Air, lung, fat, soft tissue (incl. blood), tendon, bone

Question 68

Rule of thumb is

Answer 68

Stiffness and speed - same direction | Density and speed - opposite direction

Question 69

Stiffness is related to ________, Density is related to ________.

Answer 69

Change in shape/"squishability" Weight

Question 70

What is the range for audible sound?

Answer 70

20Hz - 20,000Hz

Question 71

What are the typical values for power in US?

Answer 71

0.004 watts - 0.090 watts

Question 72

What are the typical values of intensity in US?

Answer 72

0.01 W/cm^3 - 300 W/cm^3