Those who were surveyed overwhelmingly supported candidates in their 40s and 50s.
"That's when leaders are not so young that they're too inexperienced, but not so old that their health is starting to decline or they're no longer capable of active leadership," Klofstad said.
"Low and behold, it also happens to be the time in life when people's voices reach their lowest pitch," he added.
Why the Rural-Urban Political Divide?
For the second part of the study, the researchers asked another group of volunteers, consisting of 400 men and 403 women, to listen to pairs of male and female recorded voices saying, "I urge you to vote for me this November." Each paired recording was based on one person whose voice pitch had been altered up and down with computer software.
Once again, the volunteers were asked to select their favorite candidates. They were also asked which voice seemed stronger to them.
The deeper-voiced candidates won 60 to 76 percent of the votes, but when the researchers analyzed the voters' perceptions of the candidates, they were surprised to find that strength and competence mattered more than age.