Maybe you should look at yourself to see why so many step so close. Are you soft spoken? Are you taking into account that if they are stepping close then maybe you should raise the volume? I have the opposite problem, so damn many people mumble or speak so soft that I would need to read lips to tell what they want. When I say "I can't hear you, you're very soft" they don't raise the volume. I step forward in hopes that closing the distance will enable me to hear and they step back and keep mumbling/whispering. Indoor voice isn't library or movie theater voice, so really look at how loud you normally talk and try talking as loud as if you were standing next to a diesel engine and needed to be heard over it.