Question

sometimes reflections of sound maybe undesirable can you give any example?

Answer 1

Sound wave also gets reflected as light waves do. Bouncing back of sound wave from the surface of solid or liquid is called reflection of sound.
Reflection of sound follows the Laws of Reflection as light wave does. This means the angle of incident wave and reflected wave to the normal are equal.
For reflection of sound a polished or rough and big obstacle is necessary