If there is nothing in front of you for miles to reflect sound waves, the absence of objects or surfaces for sound to bounce off would result in less sound being reflected back towards you or towards someone standing behind you. In such a scenario, the sound waves produced by your voice would likely dissipate or spread out quickly, diminishing their intensity and making it challenging for someone standing behind you to hear you clearly.
Sound waves rely on reflections to propagate and reach our ears. When you speak, sound waves are generated and travel in all directions. Some of these sound waves would be directly transmitted towards the person behind you, but without objects to reflect and redirect the sound waves, they would disperse and weaken as they travel through the open space. Consequently, the person standing behind you would likely only hear faint or muffled sounds, if anything at all.
It's worth noting that the specific audibility would depend on various factors, including the distance between you and the person behind you, the ambient noise levels, the presence of any obstructions that could partially reflect the sound waves, and the sensitivity of the listener's hearing. However, in a vast open space without any reflective surfaces, the sound would likely not travel far or be easily heard by someone standing directly behind you.