When a wave strikes a new medium, three things can happen: reflection, transmission, and absorption. Consider an echo. Do you think reflection is an important process when sound waves produce an echo?

YES

Explanation:

An echo may be defined as a sound which is repeated because of the sound waves that are produced are reflected back after striking a surface. Sound waves can smoothly bounce off the hard objects in the same manner as a rubber ball bounces back the ground.

When a sound wave strikes a hard surface, the sound waves gets reflected back and bounces back to the observer and produces an echo. If the sound waves strikes a soft surface it absorbs the sound.

Although the direction of a sound changes but the echo sounds in the same way as the original sound.

snell's law

refractve index = sin incidence / sin refraction