People who speak in a lower pitch are more likely to be promiscuous, a new study claims – and it's likely due to testosterone. An international team of researchers analysed voice recordings of more than 2,000 people – both men and women – as well as their self-reported personality traits. They found that lower voice pitch was linked with higher levels of sociosexuality – an openness to engage in casual sex. People with deep voices were also found to be more extroverted and have greater 'dominance', meaning they have high levels of influence in social situations. The experts think personality may at least partly be expressed in people's voice pitch, and that vocal cues play an important role in our initial evaluation of a person, along with physical appearance.