Ch 1-4 8

Question 0

The molecules vibrate in the same direction as the sound travels. I.e, sound waves.

Answer 0

Longitudinal Wave

Question 1

When one value increases, and so does the other value, the two values are said to be ___________.

Answer 1

Directly Proportional

Question 2

The molecules vibrate at 90 degrees to the direction of energy travel. i.e. Water ripples

Answer 2

Transverse Wave

Question 3

concentration of force

units: lb/sq inch, Pascals Pa

Answer 3

Pressure

Question 4

concentration of mass or weight

units: kg/cubic cm

Answer 4

Density

Question 5

measure of particle motion

units: cm, feet, miles

Answer 5

Distance

Question 6

The distance of one wave cycle.

Answer 6

Wavelength

Question 7

•The length of time it takes to complete one single cycle of sound or to one complete single wavelength.

Units: seconds, msec, hours – all units of time
=1/frequency

Answer 7

Period

Question 8

The # of wave cycles per second.

1 cycle per second = 1 hertz Hz

Answer 8

Frequency

Question 9

The speed at which wave cycles travel.

Answer 9

Propagation Speed

Question 10

(Sin Angle of Incidence)/(Sin Angle of Refraction)= c1/c2

Where c1 & c2 are the speeds of sound in the two mediums

Answer 10

Snell’s Law

Question 11

Z=P/V
Where P = excess pressure and
V=the particle velocity.          OR
Z=P x c
Where c=speed of light

Answer 11

Acoustic Impedance

Question 12

The dominant factor in attenuation (80%).

-conversion of sound to heat

Answer 12

Absorption

Question 13

Occurs at a boundary between 2 different media with different impedances.
-the sound bounces back (toward transducer)

Answer 13

Reflection

Question 14

z=P x V , measured in Rayls. (z=Density x Prop Speed)

Answer 14

Impedance

Question 15

Smooth surface that causes sound to bounce back toward the transducer.

Answer 15

Specular Reflector

Question 16

Scatter returning in the same general direction as the transducer.

Answer 16

BackScatter

Question 17

Interface has irregularities one wavelength or smaller.

Answer 17

Non-specular scattering.

Question 18

Sound scatters symmetrically in all directions. Not related to incidence angle. Increase frequency, and increase this.

Answer 18

Rayleigh scattering.

Question 19

%R=Reflected Intesity/Incidence Intensity=((z2-z1)/(z2+z1))^2

Answer 19

Intensity Reflection Coefficient

Question 20

90 degrees. (Porn)

Answer 20

Normal Incidence

Question 21

not 90 degrees

Answer 21

Oblique Incidence

Question 22

a bending from a straight line or path or a change in direction of a wave travelling from one medium to another. Must have two things: an Oblique Incidence, and2 media with different propagation speeds. Related to the change in acoustic velocity. (If medium 2 is faster, then it will increase the transmit angle.

Answer 22

Refraction

Question 23

Sin (angle of transmit)/ sin (angle of incidence)=prop speed 2/prop speed 1

Answer 23

Snell’s Law

Question 24

"bulk modulus." The extent to which a material cannot be compressed. To increase this will increase propagation speed.

Answer 24

Stiffness

Question 25

aka Harmonics

Answer 25

Non-linear Propagation

Question 26

Pulse, then listen for echo

Answer 26

Puled Ultrasound

Question 27

Time from the start of one pulse to the end of the same pulse. THis can only be changed by changing the transducer.

Answer 27

Pulse Duration

Question 28

% of the time that the system is transmitting a pulse and not "listening." Determined by the sound source.

Answer 28

Duty Factor

Question 29

of pulses that occur in a single second(Hz/sec). Determined by the sound source.

Answer 29

Pulse Repetition Frequency (PRF)

Question 30

Time from the start of a pulse to the start of the next pulse (includes "listening time"). Determined by the sound source. CAN be changed by the sonographer by changing the listening time. = 1/PRF

Answer 30

Pulse Repetition Period (PRP)

Question 31

The distance a pullse occupies in space. # of cycles in a pulse x wavelength. Determined by the sound source and the medium. Cannot be changed by the sonographer. Increase freq, Increase this

Answer 31

Spatial Pulse Length

Question 32

Weakening of a sound wave as it travels through media. Decrease in amplitude and decrease in intensity. Increase frequency and increase this

Answer 32

Attenuation

Question 33

+3 Db doubles the sound | +10 dB ten times the sound

Answer 33

Decibels

Question 34

value that expresses how different materials attenuate the sound beam per unit length (dB/cm). The average attenuation coefficient in soft tissue is 1/2 the transducer frequency.

Answer 34

Attenuation Coefficient

Question 35

The distance the sound beam travls when its intensity is reduced to 1/2 its original value.

Answer 35

Half-Value Layer

Question 36

The fraction of the original intensity after attenuation.

Answer 36

Intensity Ratio

Question 37

a peak aligns with a peak; increase in amplitude

Answer 37

Constructive Interference

Question 38

a peak aligns with a trough; decrease in amplitude

Answer 38

Destructive Interference

Question 39

Distance to Boundary = (go-return time x speed)/2 | d=ct/2

Answer 39

Range Equation

Question 40

Every 13 microseconds of go-return time means the reflector is 1 cm deeper in the body

Answer 40

13 microsecond rule

Question 41

when wave peaks and troughs continue to line up.

Answer 41

In-Phase Wave

Question 42

When troughs from one wave continually line up with the peaks from another wave.

Answer 42

Out-of-Phase Wave

Question 43

The strength of the sound beam, maximum variation from the baseline (dB)

Answer 43

Amplitude

Question 44

The rate that work is performed, rate of energy transfer in the entire beam. Measured in watts. P=I x CS P is proportional to Amplitude squared

Answer 44

Power

Question 45

Concentration of energy in certain areas of the sound beam | I=P/CS (watts/cm^2)

Answer 45

Intensity

Question 46

The highest intensity area or time of the sound beam

Answer 46

Peak

Question 47

(Peak + low + medium)/3

Answer 47

Average Intensity

Question 48

Greatest at the center and in focal zone of the sound beam

Answer 48

Spatial Intensities

Question 49

Occurs with Time

Answer 49

Temporal non-uniformity

Question 50

Is greatest at the center of the beam

Answer 50

Spatial non-uniformity

Question 51

Related or proportional

Answer 51

Related, Proportional, Directly Proportional

Question 52

As one value increases, the other value decreases.

Answer 52

Inversely proportional.

Question 53

The effects that are made on the human body

Answer 53

Biological Effects

Question 54

The thing that is creating the sound wave

Answer 54

Source

Question 55

The material that the sound wave is traveling through

Answer 55

medium