Joan got a call from her boss, Shelly. “I knew from the sound of her voice, when she said hello and asked how I was, that someone else got the promotion I was up for,” Joan told me. “I also knew that Shelly was unsure about her decision.”

How did Joan know all that from just the sound of a few neutral words?

Paralinguistic communication, also known as “vocal body language,” is the answer. Volume, pitch, inflection, pace, rhythm, rate, intensity, clarity, pauses – all of these play a role in how you say what you say – and that “how”can sometimes be more revealing of your true intent than the “what” contained in the words.

Leaders must therefore keep in mind that when they speak, their listeners won’t only be evaluating their words, they will also automatically be “reading” their voices for clues to possible hidden agenda, concealed meanings, disguised emotions unexpected surprises – anything, in short, that will help them to determine if they can rely on what they’re being told.

Your voice is as distinctive as your fingerprint. It conveys subtle but powerful clues into feelings and meanings. Think, for example, how tone of voice can indicate sarcasm, concern, or confidence. Or how an increase in volume and intensity grabs attention because of the heightened emotion (passion, anger, assertiveness, certainty) it signals.

The limbic brain, where emotions are processed, also plays the primary role in how people process your vocal cues. Researchers from the University of Geneva in Switzerland discovered that they could tell whether a subject had just heard words spoken in anger, joy, relief, or sadness by observing the pattern of activity in the listener’s brain.

The effect of paralinguistic communication is so potent that it can, for example, make bad news sound palatable or, conversely, take all the joy out of a positive message. I’ve seen managers give unflattering feedback while still exhibiting warm feelings through their tone of voice – and those who were being critiqued still felt positively about the overall interaction. I’ve also seen managers offer words of praise and appreciation in such a flat tone of voice that none of the recipients felt genuinely acknowledged or appreciated.

One of the most intriguing aspects of vocal behavior is speech convergence – the way people adopt the speech patterns and voice qualities of those with whom they admire and want to be like. In fact, influence in an organization can be predicted by analyzing speech patterns. Those individuals who have the greatest effect on the greatest number of people (in terms of changing their speaking style) will also have the most control of the flow of information within the organization. When you find the people in your organization who cause the most speech convergence, you also find the influential, informal leadership.

Speech convergence can also be used as a technique to help people understand your message. The more adept you are at altering your speed, volume and tone to match that of the group you are addressing, the better they will hear and accept what you have to say.

As a leader, you are asking people to put aside their personal agendas and egos in the service of collective solutions that benefit the entire organization. For this to have any chance of happening, team members must know that you are 100 percent committed to their success. So, when you say that you trust, support and believe in your team, you’d better sound like you mean it.