Focussed sound : the exhibit

In this video exhibit on sound is demonstrated. One friend face a parabolic reflector with his/her ear close to the central ring and another friend go to the other reflector and put the own mouth close to the central ring . Talk another friend with normal voice and ask another friend to speak close to the ring , get near the ear close to the ring and listen. The central ring is placed at the focus of the parabolic reflector. Sound originating at one focus gets reflected by the surface and travels in parallel lines to the other reflector. There sound is converged to the focus of the reflector. Without such reflectors sound energy gets lost the air.