Describing Sound Waves

Question 1

What are parameters?

Answer 1

They describe features of a sound wave.

Question 2

What are the seven parameters?

Answer 2

1. Period
2. Frequency
3. Propagation speed
4. Wavelength
5. Amplitude
6. Power
7. Intensity

Question 3

What is a period?

Answer 3

It is the time it takes a wave to complete a single cycle.

Question 4

What units is period reported in?

Answer 4

Units of time.

Question 5

What is the period determined by?

Answer 5

Determined by the sound source only.

Question 6

Is the period adjustable?

Answer 6

No.

Question 7

What is frequency?

Answer 7

It is the number of events that occur in a specific duration of time.

The number of cycles that occurs in one second.

Question 8

What unit is frequency reported in?

Answer 8

Reported in units of per second.

Question 9

What is frequency determined by?

adjustable?

Answer 9

It is determined by the sound source only and it is not adjustable.

Question 10

What is considered below the threshold of human hearing?

Answer 10

A frequency of a sound wave less than 20 Hz.

Question 11

What is the name for sound waves that have a frequency lower than 20 Hz?

Answer 11

Infrasound.

Question 12

What frequency range can humans hear?

Answer 12

Between 20 Hz and 20,000 Hz

Question 13

Why is frequnecy important in diagnostic sonography?

Answer 13

It is important because it affects the penetration and image quality.

Question 14

What is the relationship between frequency and period?

Answer 14

Inversely related.

Question 15

What is the equation for period?

Answer 15

Period= 1/F

Question 16

What frequency is audible?

Answer 16

Between 20 Hz and 20 kHz

Question 17

What frequency is ultrasound?

Answer 17

Greater than 20 kHz

Question 18

What are the 3 “bigness” parameters that describe the size, magnitude, or strength of a sound wave?

Answer 18

1. Amplitude
2. Power
3. Intensity

Question 19

What is amplitude?

Answer 19

It is the bigness of a wave.

Question 20

What is the amplitude determined by?

Answer 20

It is determined by the sound source only.

Question 21

What happens to amplitude as it travels through a medium?

Answer 21

It decreases as sound propagates.

Question 22

Is amplitude adjustable?

Answer 22

Yes.

Question 23

What is power?

Answer 23

It is the rate at which work is performed.

Question 24

What is power determined by?

Answer 24

It is determined by the sound source only.

Question 25

What happens to power as ir travels through the body?

Answer 25

Like amplitude, it decreases as sound propagates through the body.

Question 26

Is power adjustable?

Answer 26

Yes.

Question 27

How are power and amplitude related?

Answer 27

Directly related. Power ≈ amplitude²

Question 28

What is intensity?

Answer 28

It is the concentration of energy in a sound beam.

Question 29

How do you calculate intensity?

Answer 29

Divide the the beams power by the beam's area. intensity (W/cm²)=Power (w)/area (cm²)

Question 30

What does intensity relate to?

Answer 30

It relates to how the power in a wave spreads or is distributed in space.

Question 31

What is the unit of intensity?

Answer 31

W/cm²

Question 32

What is whats determined by?

Answer 32

initial intensity is determined by the sound source only.

Question 33

Is intensity adjustable?

Answer 33

Yes.

Question 34

How is intensity related to power?

Answer 34

It is directly proportional.

Question 35

How is intensity related to power?

Answer 35

It is directly proportional to the waves amplituded squared.

Question 36

What is wavelength?

Answer 36

It is the **distance** of one complete cycle.

Question 37

What is the unit of wavelength?

Answer 37

It is measured in units of length.

Question 38

What is the wavelength determined by?

Answer 38

**Both** sound source and medium.

Question 39

Can wavelength be adjusted?

Answer 39

No.

Question 40

What is the only parameter that is determined by both the sound source and medium?

Answer 40

Wavelength.

Question 41

What is the relationship between wavelength and frequency?

Answer 41

Inversely related

Question 42

What is the wavelength of 1 MHz sound in soft tissue?

Answer 42

1.54mm

Question 43

What is the equation for wavelength?

Answer 43

wavelength (mm)= 1.54 (mm/us) / frequency (MHz)

Question 44

What type of wavelength creates a better and clearer image?

Answer 44

Shorter wavelength because it is created by higher frequencies.

Question 45

What is propagation speed?

Answer 45

It is the rate at which a sound wave travels through a medium.

Question 46

What is the unit of speed?

Answer 46

It is measured in used of distance/time

Question 47

What is speed determined by?

Answer 47

Speed is determined by the medium.

Question 48

Can speed be adjusted?

Answer 48

No.

Question 49

What is the speed of sound in soft tissues?

Answer 49

1540 m/s

Question 50

What is the equation for speed?

Answer 50

Speed (m/s)= frequency (Hz) x wavelength (mm)

Question 51

What characteristics of a medium determine the speed of sound in that medium?

Answer 51

stiffness and density.

Question 52

What is stiffness?

Answer 52

It is the ability of an object to resist compression.

Question 53

How does stiffness affect speed?

Answer 53

They are directly related. \*As materials become stiffer, the speed of sound in the material increases.

Question 54

What is density?

Answer 54

Describes the weight of a material.

Question 55

How does density affect speed?

Answer 55

Density and speed are inversely related. \* As materials become more dense, the speed of sound decreases.