An acoustic reflector comprises a shell surrounding a solid elastomeric core free of joints. The shell transmits acoustic waves incident on the surface of the shell partially into the core to be focused and reflected from an area of the shell located opposite to the area of incidence so as to provide a reflected acoustic signal output from the reflectorpartially around the circumference of the shell and to combine constructively with the reflected acoustic signal output. The ratio of the speed of sound wave transmission in the shell to the average speed of the wave transmission in the core is preferably in the range of 2.74 to 3.4 best results being in the range of 2.74 to 2.86 inclusive.