Voice voting is used at civic, local and county government meetings and also employed regularly in Congress and in state legislatures to pass resolutions. But the process can be confusing and even produce erroneous results, researchers at the University of Iowa said.
They said they calculated it would take at least 40 normal loudness voices to overcome the bias of a single loud vote, to establish roughly a two-thirds majority.
"All voters should realize that a soft (voiced) vote is basically an abstaining vote and that one loud vote is equivalent to many votes with normal loudness," said Ingo Titze, a professor in the university's Department of Communications Sciences and Disorders.
In an experiments, the researchers assembled 54 student "voters" in a spacious classroom, with five "judges" positioned at the front, closing their eyes when judging loudness.
The student voters were divided into two camps -- ayes and nays -- and then instructed to shift their numbers and the loudness of their voices, to simulate various voice-vote scenarios.
"In a small group, a single voter can skew a two-thirds majority by simply speaking louder than the other voters," Titze said of the experiment's result. "And unless individual loudness is controlled, any voice vote for a simple majority is highly suspect."
Still, he said, "there's something to be said about hearing people's emotions when an issue comes before them. Voice voting may not be useful to make a final decision, but at least it gives people the chance to express themselves verbally, and there's some value in that."