Acoustic Impedance

Question 1

What is it meant by the term acoustic impedance?

Answer 1

It is the Property of substance which describes how the particles of that substance behave when subject to a Pressure wave i.e. sound wave

Question 2

Explain the properties of the substance which determines its Acoustic impedance?

Answer 2

Particle velocity + Excess pressure
Bone Densely packed material in the substance
Soft tissue/air Loosely packed particles hence Lower Excess pressure to move them At a velocity

Question 3

Acoustic impedance

Answer 3

Measure of the substance as to the propagation of a Soundwave through it

Question 4

What happens in substances with a small difference in acoustic impedance?

Answer 4

Small amount of energy is reflected plus majority transmitted

Question 5

What happens In a substance with a large difference in acoustic impedance?

Answer 5

Large amount of Reflection/ Less transmitted energy

Question 6

Same acoustic impedance in substances?

Answer 6

Total transfer of energy

Question 7

If there is a large acoustic mismatch example between bone Soft tissue, what happened?

Answer 7

Large reflection creating strong echos - Bright image

Question 8

Large acoustic impedance mismatch mean?

Answer 8

U/s Will not produce a useful image beyond that surface

Question 9

Why u/s Is good at imaging Different soft tissues?

Answer 9

Due to small mismatch in acoustic Impedance