Forget the board room. Women's voices are barely even present on earnings calls.

Corporate America's most important publicly conducted discussions—the quarterly earnings calls held by almost all listed companies—are dominated by men, who talk more often and speak longer than women, according to research done at Bloomberg's request by Prattle, a company that provides automated research by parsing central bank and corporate communications.

In a study of more than 155,000 company conference calls over the past 19 years, Prattle found that men spoke 92 percent of the time. That's partly because male executives and analysts far outnumber women in those roles. It's also because men just talk more.