Wk 2 - Acoustic Impedance

Question 1

What is acoustic impedance?

Answer 1

A measure of how easily a sound wave propagates through a particular medium

• unit is the ohm
• mediums in which the speed of sound differ have different acoustic impedances
• impedance mismatches result in some of the wave reflected and some transmitted into the 2nd medium

Question 2

Regarding waveforms in the cochlea, which two measures are 180 degrees out of phase?

Answer 2

Displacement (& stiffness effects) are 180 degrees out of phase with acceleration (and mass effects)
- both are 90 degrees out of phase with velocity (and force)

Question 3

Regarding waveforms in the cochlea, which measure leads velocity (and force) by 90 degrees? Which one lags by the same amount?

Answer 3

Acceleration (and the impact of mass) leads by 90 degrees.

Displacement (and stiffness) lag by 90 degrees.

Question 4

Velocity is in phase with force, therefore so is the impact of ______

Answer 4

Resistance

Question 5

______ is maximal at the forces zero crossings, and 0 at its peaks

Answer 5

Acceleration

Question 6

_______ is 0 at the forces zero crossings, and maximal at its peaks

Answer 6

Displacement

Question 7

Force and velocity are related by ______

Answer 7

Impedance (Z)