Those in the audience included members of various voting groups, such as the League of Women Voters, and Stella Anderson, a member of the North Carolina Board of Elections.

“I’m here to learn and to listen and to take back concerns to the board,” Anderson said.

Other speakers included Bennie Smith, a data analyst and county election commissioner in Shelby County, Tenn. Smith found a glitch in the system there that counted some votes in fractions.

Harri Hursti, an election-security researcher at Nordic Innovation Labs, said machines with problems uncovered even a decade ago remain in use and that hackers would only need the internet to access them. He said others need access only to a machine’s memory card.

“Everything I’ve been seeing is unbelievable,” Hursti said.

Andrew Appel of Princeton University said he was asked by a judge to review a contest in a small district. He said the plaintiff got affidavits from voters in the district, leading to the judge’s actions. The affidavits and a programming error showed that the votes had been swapped. Appel and the others suggested paper ballots, which offer the potential for an audit and which is what the NAACP would like to see.

“We don’t know if it was hacked or if it was a mistake,” Appel said of the mistaken results in the contest. “Those things do happen. Our only protection is the paper ballot.”

Contact Nancy McLaughlin at 336-373-7049 and follow @nmclaughlinNR on Twitter.