Chapter 3 - p.53 Flashcards
________ mean sa diminishing ro decrease
Attenuation
Attenuation is the result of 3 wave interactions with the medium ____ , ___________ and __________
absorption, reflection and refraction
In soft tissue ___________ is the dominant factor creating attenuation.
absorption
___________ is the conversion of energy from sound waves into heat within the medium
absorption
Absorption increases with the increasing __________
frequency
The word ________ refers to the bending of a ray or beam at an interface between two different media
refraction
Refraction is governed by __________ law.
Snell’s
__________ law for refraction depends on the ration of the propagation ________of two different median at an interface and the incident angle.
Snell’s
velocity
The term -____________ in reference to angles mean the same as zero degree incidence
normal
For -___________ incidence there can be no -__________
normal
refraction
For normal incidence, the amount of reflection is det. by the acoustic ________ mismatch.
impedance
The acoustic impedance has units of ________-
Rayls
The acoustic impedance equals the __________ times the ________ ___________
density
propagation velocity
Density has units kg/m^3 and the propagation velocity has units of m/s. So, 1 Rayl equals __________
1 kg/ (m^2 x sec)
A large impedance mismatch will result in high percentage of _______ or equivalently a ___________ percentage of transmission
reflection
low
