1) In big theaters, the walls behind the speaker are made spherical and the speaker stands at the focus of that, so that sound is reflected towards the audience and the audience can hear it clearly.
2) In a megaphone, the principle of reflection of sound is used, the shape of megaphone is such that the sound after reflection goes in the forward direction.
3)Reflection of sound also has applications in the ultrasound technology, which is used to detect the presence of any foreign object in the body or in the detection of any defect in the development of the fetus.
4)Bats cannot see in the dark. So, they use the reflection of sound to find their path and to avoid any obstacles in their path. They emit sound which we an't hear and when the sound reflects, they come to know about the obstracle in their path.