How does your voice change when you lie? --- Jorje, Brisbane, Australia
There are lots of body-language indicators that are supposed to let you detect lying. For example, if a person looks in a certain direction, or touches his or her nose, it is supposed to indicate lying. In the same way, a rise in voice pitch is supposed to indicate lying. For more info see: How Lying Works and How Lie Detectors Work.
The problem with all of these indicators is that they don't always indicate lying. In fact, they often do not, and may instead be signs of nervousness. See How Lie Detectors Don't Work for details.