Reflection
I say that the wave that hit the obstacle is bounced and reflection.Given
by paying attention to the direction of travel waves during the reflection
angle θ with the incident angle θ is
There is a relationship that, I called the law of reflection this.
Refraction
Between the waves will spread, there is a medium of a variety of conditions
or different material, or the temperature is different.Vibration applied
to the wave source determines the frequency but earliness and wavelength
varies depending on the medium.
Wave passes through the boundary surface of the medium of two different
speed changes at the same time any part of the wavefront if incident straight,
as it is, go straight.The incident at an angle, the speed will change in
the order in which they arrived at the boundary surface.
Difference in early difference occurs between the wave that arrived at
the boundary surface at the beginning, with the wave that arrived later,
as a result, the traveling direction of the wave front is not the same
as before it reaches the boundary surface. I called the refractive this.There
is the following relationship between the angle of refraction and the angle
of incidence, I called the law of refraction. 
