Answer:
When a wave reaches the boundary between one medium another medium, a portion of the wave undergoes reflection and a portion of the wave undergoes transmission across the boundaryr:
Step-by-step explanation:
When sound changes mediums (enters a different material) at an angle other that 90 degrees, it is bent from its original direction. This change in angle of direction is called refraction. Because of the angle, part of the wave enters the new medium first and changes speed