There’s a science and an art to persuasion. Researchers at the University of Michigan analyzed the speech of 100 interviewers on 1,380 calls as they tried to persuade people to participate in a survey. Here’s what they learned.

• Talk Fast

  Researchers found that optimal persuasive speed is a little faster than normal—about 3.5 words per second. Hyperspeed can sound shady, and slow-talkers come across as dull or didactic.

• Take a Breath

  Interviewers who spoke perfectly were the least likely to hook a listener. It’s best to pause about every 20 seconds.

• Mind Your Pitch

  Get enthused but be wary of being too boisterous. Men who varied their pitch a lot were less persuasive than those who didn’t. But women who varied their pitch were more successful than those who didn’t. As with men, a lower pitch also helped slightly, which was a surprise, because research has shown that higher female voices are viewed as more attractive.