Ex-FBI hostage negotiator: Why you should ditch an 'assertive' voice and use this negotiation style instead

Christopher Voss, Founder and CEO of Black Swan Group speaking at Iconic L.A. on Sept. 27th, 2017.
David A. Grogan | CNBC

Former FBI hostage negotiator Chris Voss knows a thing or two about talking his way out of any situation: He was the lead kidnapping negotiator for the FBI and a member of the New York City Joint Terrorist Task Force for 14 years.

Now, Voss teaches negotiation training for businesses and individuals through his company The Black Swan Group.

Voss says while he can't teach exactly the right thing to say in every situation, if you master the right tone when negotiating, everything will probably end up fine.

"Your voice, your delivery, speaks volumes," Voss tells in his 18-part series on the art of negotiation. It can convey everything from deference to curiosity to collaboration, he says. "Your voice alone can be such art."

Voss says his FBI training taught him to use a "late-night FM DJ" voice when negotiating with bank robbers, kidnappers or even terrorists. To Voss, an FM DJ voice has warmth to it, as opposed to an analyst voice.

"We knew it calmed them down. We didn't know why. We didn't care. We knew that was the law of gravity: 'Calm the other side down,'" Voss says.

It is also key to smile when negotiating because it triggers the other person's mirror neurons (nerve cells in the brain that "mirrors" the behavior of another individual's actions) in a positive way. Voss says if you smile during a negotiation, you will likely calm down the other person and "tamp down their emotions," which will make the other person more pliable in the end.

But one of the biggest mistakes Voss sees people make during negotiations is using a firm, assertive voice when trying to get their messages across.

"In the real world, I have seen that anger always leaves a negative residue — always. And anger is always bad for long-term relationships. And that's the reason that we tell people who are natural born assertives, 'You gotta fix that voice, [because] it's always counterproductive,'" Voss says.

Instead use a "playful voice," says Voss. Also known by FBI negotiators as the "accommodator's voice," it's a style of speaking that's likable, charming and relaxed in tone, but still relays the truth.

For example, if Voss were a salesman trying to sell a high-priced item to someone, instead of flatly saying, "It's $35,000," he would say something like, "Ah, I know this is crazy, it feels like a lot, but I wanna work with you on this."

"I don't want you to feel backed into a corner," says Voss. "I want to say it to you in a way that it keeps a relationship."

"The playful voice should be the voice that you use about 80% of the time," Voss says. "You wanna keep people in a positive frame of mind."

By keeping people positive even in difficult situations, you keep them thinking, says Voss, and they will continue to work with you even if there's no resolution in sight.

Also, don't forget to keep smiling throughout even when you're not speaking.

"The smiling voice is a tremendously effective (vehicle), and it should really be your default voice. It will serve you well. Use it the vast majority of the time," he says.

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Former FBI negotiator: This one phrase can help you win any argument
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