What do you mean by reflection of sound waves?

Reflection of Sound waves

When there exists a discontinuity in the medium, the wave gets reflected. When a sound wave gets reflected from a rigid boundary, the particles at the boundary are unable to vibrate. Thus, a reflected wave is generated which interferes with the oncoming wave to produce zero displacement at the rigid boundary. At these points the pressure variations is maximum. Thus, a reflected pressure wave has the same phase as the incident wave,. That measn, a compression pulse reflects as a rarefaction pulse.

 A sound wave is also reflected if it encounters a low pressure region. A practical example is when a sound wave travels in a narrow open tube. When the wave reaches an open end, it gets reflected. The force on the particles there due to the outside air is quite small and hence, the aprticles vibrate with increased amplitude. As a result, the pressure there remains at the averrage value. Thus, the reflected pressure wave interferes destructively with the oncoming wave. There is a phase change of pie in the pressure wave when it is feflected by an open end. That means, a compressive pulse reflects as a rarefaction pulse and vice versa.