Acoustic reflectors are used in many applications. In other words, you may treat the problem as a geometrical one in which sound rays spread out from the source in straight lines and are reflected from the surfaces according to the law of reflection. Sound rays are simply imaginary lines drawn from the sound origin in all possible directions of propagation. This rule also applies to curved surfaces like cones and parabolas. Horn shapes have been used for a very long time to improve the radiation or reception of sound waves.
Effective horns have very hard walls that absorb as little sound energy as possible.
A simple horn is not an extremely effective way to locate sounds because it is open to capture sounds from so many directions. Devices like the one shown in figure 5 have been used as directional sources and receivers of sound. Only the sound waves entering from a direction parallel to the tubes do not cancel each other out at the other end. When two waves from a source take two paths, one could get ahead of the other and would be called out of phase. In a tube, the phase velocity of a sound wave is practically equal to free sound speed, therefore all components of the sound wave through the tubes arrive in phase.