Mod 1 Unit 3 (Sound Interaction With Matter)

Question 1

What is attenuation?

Answer 1

decrease in wave amplitude/power as it travels through a medium

Question 2

Types of attenuation

Answer 2

Absorption, reflection/scattering, refraction

Question 3

What is absorption?

Answer 3

main type of attenuation, energy into heat, non-linear exponential

Question 4

Absorption depends on

Answer 4

medium type (viscosity) and frequency

Question 5

A higher frequency does what to the attenuation, penetration, and resolution?

Answer 5

increases attenuation, decreases penetration, increases resolution

Question 6

A lower frequency does what to the attenuation, penetration, and resolution?

Answer 6

decreases attenuation, increases penetration, decreases resolution

Question 7

Higher viscosity means that

Answer 7

there is more energy to move molecules therefore more absorption

Question 8

Water and fluid creates what artifact and why?

Answer 8

posterior enhancement artifact because the viscosity is low

Question 9

Bone creates what artifact and why?

Answer 9

posterior shadowing artifact because the viscosity is high

Question 10

Posterior shadowing occurs due to

Answer 10

high attenuation

Question 11

Posterior enhancement occurs due to

Answer 11

low attenuation

Question 12

What is acoustic impedance?

Answer 12

transfer of sound energy from one medium to another

Question 13

No AI difference=

Answer 13

no reflection

Question 14

AI Z value is based on what two factors?

Answer 14

density and propagation speed

Question 15

What is reflection?

Answer 15

propagating wave changes direction with some loss of energy + AI changes

Question 16

Factors of image formation

Answer 16

absorption, AI differences, specular reflection, scatter/diffuse reflection, rayleigh scattering + resulting artifacts

Question 17

What kind of speckle pattern do you get with a high frequency?

Answer 17

fine