When parallel beams of light fall on a very smooth surface, the rays are reflected in parallel.  

The rays are reflected in many different directions.  The angle of incidence still equals the angle of reflection.  Since the surface is rough, the normal lines are in every direction.  You can see a diffuse reflection from all directions.

An echo is reflected sound.  Sound reflects from all surfaces - the walls, ceiling, floor, furniture, and people - of a room.  The study of reflective properties of surfaces is called acoustics.  When the walls of a room, auditorium, or concert hall are too reflective the sound becomes garbled.  A reverberation is multiple reflections.

When the reflective surfaces are more absorbent, the sound is lower.  You would want a concert hall to have a mix of absorption and reverberation.  The walls of a concert hall are designed with grooves so that the sound waves are diffused.  Both sound and light obey the same law of reflection, so if you can see an instrument of someone playing in the orchestra pit from a mirror, then you can hear that instrument also

With grooved walls, as in picture a, sound reflects from many small sections of the wall to a listener.  Rough walls give a room a feel of full and lively sound.  With flat walls, like in picture b, an intense reflected sound comes from only one part of the wall.  Smooth walls fail to give the room a feel of full sound.