Can you tell if someone is lying? Close your eyes. You’re already twice as good as you were before. Our voices change in an instant. When you’re hit by a surge of adrenaline, your fight-or-flight response triggers muscles around your larynx, making your voice high-pitched and wobbly. When you answer the phone to someone you love, your voice softens and deepens. When someone lies, the rhythm and intonation of their speech change. And, weirdly, you are almost twice as good at spotting that distortion if you only hear – not see – them speak. Our voices give away a huge amount of information with every sentence, and human beings are remarkably good at interpreting these subtleties. But what exactly are our voices revealing, and how do our brains process that information? I volunteered as a Samaritan at university. After the initial training, I spent hundreds of hours listening to callers as they talked about everything from unreciprocated crushes to financial crises to the death of someone dear.…