Attenuation, Reflection, & Scattering Flashcards
As sound propagates through a medium, the total power in the wave decreases. What is this entire process called?
a. absorption
b. scattering
c. attenuation
d. reflection
c. attenuation
Attenuation is determined by which of the following factors?
a. density and stiffness of the medium
b. frequency of sound and propagation speed
c. PRF of sound and path length
d. path length and frequency of sound
d. path length and frequency of sound
An acoustic wave is traveling through soft tissue. Its intensity undergoes six decibels of attenuation. How does the final intensity of the wave relate to the inanity of the wave when it started its journey?
a. it is now four times larger
b. it is now six times larger
c. it is now one-fourth as large
d. it is now one-tenth as large
c. it is now one-fourth as large
Which of the following is not one of the physical processes that contributes to attenuation of ultrasound waves passing through soft tissue?
a. reflection
b. redirection of sound in many directions
c. focusing
d. conversion of acoustic energy to heat
c. focusing
An acoustic pulse reflects from a very smooth boundary where the irregularities on the surface of the boundary are much smaller than the pulse’s wavelength. What type of reflection is most likely to occur under these circumstances?
a. partial
b. Rayleigh
c. specular
d. total
c. specular
A sound wave reaches a rough or irregular border between two media. Under these explicit circumstances, which process is most likely to occur?
a. backscatter reflection
b. specular reflection
c. Rayleigh scattering
d. refraction
a. backscatter reflection
Which of the following is true of diffuse reflections?
a. they’re created by smooth boundaries
b. they’re created by large reflectors
c. sound reflects in many directions
d. they do not appear in soft tissue
c. sound reflects in many directions
What is the uniform dispersion of a sound wave in many different directions after striking a very small particle?
a. microscattering
b. backscattering
c. Rayleigh scattering
d. total absorption
c. Rayleigh scattering
Which of the following is considered a Rayleigh scatterer?
a. bone
b. liver
c. muscle
d. blood cell
d. blood cell
To which of the following is Rayleigh scattering related?
a. half of the wavelength
b. square root of propagation speed
c. frequency^4
d. PRF^2
c. frequency^4
As a pulse passes through soft tissue, a certain amount of acoustic energy remains in the tissue as heat. What is this constituent of attenuation called?
a. scattering
b. absorption
c. refraction
d. rarefaction
b. absorption
What is the amount of attenuation per centimeter that a sound wave undergoes called?
a. beam uniformity coefficient
b. attenuation coefficient
c. attenuation
d. duty factor
b. attenuation coefficient
A sound beam travels 9 cm in soft tissue. The attenuation coefficient is 3 dB/cm. What is the total attenuation that the sound beam experienced?
a. 9 dB
b. 3 dB
c. 27 dB
d. 18 dB
c. 27 dB
The attenuation of an acoustic wave traveling through bone is ____ its attenuation through soft tissue.
a. greater than
b. less than
c. equal to
a. greater than
Ultrasound waves traveling through lung tissue attenuate to a ____ extent than when traveling through soft tissue.
a. greater
b. lesser
c. nearly equal
a. greater
