Reflection of Sound

Why do we put cushions on the chairs, carpet on the floor, straw materials on the walls in cinema halls?

What is the advantage of having conical openings in Horns, megaphones etc?

In a closed box if you say hello, the sound heard will be Hellooooo.....  What does it mean?

Why is an echo weaker than the original sound?

What could be the reason for better reflection of sound by rough surfaces than polished surfaces?

Do hard surfaces reflect sound better than soft ones?

A man is lying on the floor of a large, empty hemispherical hall, in such a way that his head is at the centre of the hall. He shouts “Hello!” and hears the echo of his voice after $0.2 \mathrm{s}$. What is the radius of the hall? (Speed of sound in air $= 340 \mathrm{m}/\mathrm{s}$)

How do echoes in a normal room affect the quality of the sounds that we hear?

How are multiple reflections of sound helpful to doctors and engineers?

Does the sound follow the same laws of reflection as light does?

Why is soft furnishing avoided in concert halls? 

Explain how echoes are used by bats to judge the distance of an obstacle in front of them.

In a stethoscope, sound of heart beats travel through stethoscopes tube _____.