“Sorry? I can’t hear you!”
“What? I can’t hear you!”

Two people had this interaction while standing next to a loud piece of machinery. Standing some distance off, I could hear both of them clearly, but they couldn’t hear each other.

Whether the environment is not conducive, or people are passionately shouting, there are many reasons two parties might not be able to hear each other. Meanwhile, those with physical or emotional distance can sometimes hear with clarity.