“Infants sort what they hear through the superior temporal sulcus (STS), located just above the ear. At four months all auditory information—whether their mother’s voice or a car horn—is attended to by the STS. But by seven months, babies start singling out human voices as the only sounds that trigger attention from the STS,6 and the STS shows especially heightened activity when that voice carries emotion. This little piece of our brain is dedicated to taking in language and reading tone and meaning. But get this: When we ourselves speak, the STS turns off. We don’t hear our own voice, at least not the same way we hear everyone else. This explains why we are so often surprised when we get feedback based on how we said something. (“Tone? I’m not using some kind of tone!”) It also helps explain why our voice sounds so unfamiliar when we hear ourselves on an audio recording. When transmitted from a speaker, our own voice gets routed through our STS, and we suddenly hear ourselves the way others do. (“I sound like that?!”) We’ve been hearing ourselves every day of our lives, and yet we haven’t.”