Perhaps more in line with Arriola's theory that Holmes was trying to appear more "convincing," other research shows that people's vocal pitch tends to change when they lie. A 2012 study found that people's voices go up in pitch when they lie, even when they're aware that their voice changes during times of "deception." Of course, it's normal for people's voices to fluctuate along with their thoughts and emotions when they talk, but some communication experts say that people tend to use a monotone voice when telling a lie . In general, people tend to change the pitch of their voice depending on who they're talking to and the circumstance. In a 2017 study, researchers found that people who see themselves as dominant are less likely to shift their (usually lower) pitch. When answering questions about conflict in particular, people in the study lowered their voice.