Spokesman Michael Signora said Friday that the league believes the problem "involved no manipulation by any individual and that the Patriots had nothing to do with it."
The statement said the problem was "entirely attributable to an electrical issue made worse by the inclement weather" and that the league "will continue to review the matter to determine if there are technical steps that can be taken to avoid similar problems from occurring in other games."
Steelers coach Mike Tomlin said after the 28-21 loss to the Patriots that Pittsburgh's coach-to-coach headsets picked up New England's radio broadcast for the majority of the first half, preventing his staff from communicating with one another.
Tomlin added that communication problems are "always the case" when playing at New England. But on Friday, the Steelers said they didn't plan to file a formal complaint.
Friday morning, a report on Steelers.com, the team's official website, said that whenever an NFL representative was on the Patriots' sideline, the Steelers' headsets cleared, but when the representative walked away, the game broadcast returned. ESPN has not been able to independently confirm that report, which was unattributed.
A source with knowledge of the NFL's reaction said Friday morning that when the league determined Pittsburgh's communications were down, it was in the process of shutting down the Patriots' headsets when the problem was resolved. The problem resurfaced briefly but was then resolved and did not recur.
Patriots coach Bill Belichick said he had problems with his headsets, too. And he said "it's just not right" that his team is repeatedly being accused of cheating.
"They told us they were on the verge of shutting it off, but then I guess they got it working," Belichick said. "I don't know, but it was a problem the whole game. We almost had to switch helmets with[Patriots quarterback Tom] Bradythere at the end. Couldn't get the plays in to him. It was a problem all night."
Houston Texans coach Bill O'Brien, who worked on Belichick's staff in various capacities from 2007 to '11, said "a headset issue happens every game. It happened in Dallas [Houston's final preseason game]. It happens here [in Houston]. It happens wherever I've been."
There have been notable instances of headset failures from past seasons:
In the 2010 AFC Championship Game between theJetsand Steelers in Pittsburgh, New York quarterback Mark Sanchez had trouble receiving calls over the radio in his helmet. At one point during the game, the Jets had to use a walkie-talkie to relay play calls to Sanchez.
In a 2005 wild-card game between the Jaguars and the Patriots in Foxborough, Jacksonville experienced communication malfunctions between coach Jack Del Rio and his assistants as they tried to send the plays in to Byron Leftwich for much of the first half. Del Rio said he asked officials to take those systems away from the Patriots but was told there was no rule requiring that.
In May, Karlos Dansby told NBC Radio that the headset in his helmet stopped working during a 2008 game at New England and that he suspected foul play. It was snowing that day, and the Patriots won in a blowout.
"My headset was working fine, every game," Dansby told Pro Football Talk, "until the very last game of the year. We get in Foxborough, they couldn't get my headset fixed, for nothing in the world."
The Associated Press contributed to this report.
NFL clears Patriots of headset suspicion
John Clayton breaks down how the NFL came to the conclusion that an electrical issue was at blame for the Steelers' headset issues during Pittsburgh's loss to New England on Thursday.
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Adam Schefter discusses why the Steelers will not file a complaint over their headsets' failing at Gillette Stadium on Thursday night.
Tomlin addresses headset issues
Steelers coach Mike Tomlin addresses the issues faced by the Steelers' coaching staff in picking up the Patriots' radio broadcast in their headsets during the game.
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Herm Edwards reacts to the Steelers' coaches' picking up the Patriots' radio broadcast in their headsets during Pittsburgh's game against New England.
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Steve Young reacts to the Steelers' coaches hearing the Patriots' radio broadcast in their headsets during their matchup Thursday night and discusses how it will affect the story of the game.