What is sound wave refraction and how do speed and frequency affect it?

[CanadianEh]

Refraction of sound is a term that refers to the fact that...

A. sound bounces off a smooth surface just as light bounces off a mirror.
B. different parts of a wave front travel at different speeds.
C. different frequencies of sound waves travel at different speeds.
D. sound waves only contain a fraction of the total energy emitted by the source.


3. I think the answer is B, but I'm looking for some clarification. Thanks

 

[Stonebridge]

The answer is B.
Answer A is reflection and answer C is dispersion.
In this diagram, the wavefront is AB moving to CD
In a time t, point A travels AC, point B travels BD
BD is a greater distance than AC.
Different points on the wavefront travel at different speeds when refraction takes place.
http://www.iop.org/activity/education/Projects/Teaching%20Advanced%20Physics/Vibrations%20and%20Waves/Images%20300/img_mid_4455.gif

 

[CanadianEh]

Thank you very very much!