"CBS has informed us that the unusual audio moment heard by fans during the Patriots-Colts game was the result of tape feedback in the CBS production truck and was isolated to the CBS broadcast," the league said. "It was in no way related to any sound within the stadium and could not be heard in the stadium."
Network officials did not give any additional details, referring only to the league's statement. The telecast received the highest rating overnight rating, 22.5, of any Sunday afternoon regular-season NFL game since at least 1987 and had a 39 share nationally.
The Web site YouTube carried a 1-minute, 10-second clip entitled "Indy Cheats" that replayed the moments in question.
On the first play of the fourth quarter, a 14-yard pass from Tom Brady to Randy Moss, the crowd noise is heard before and during the play, then immediately cuts out when Moss is tackled. In addition, there appeared to be a vibration in the sound while the crowd was cheering.
A published report on yahoo.com said Patriots president Jonathan Kraft complained to NFL vice president of security Milt Ahlerich afterward. Kraft is the son of Patriots owner Robert Kraft.
Any enhancement of crowd noise would violate NFL rules, and Patriots spokesman Stacey James denied the team either filed or intended to file a formal complaint with the league.
It's not the first time Indianapolis has been accused of such tactics. The Pittsburgh Steelers complained about the same thing after a 26-7 loss at the dome in November 2005. Since then, other teams have informally contended there is artificial noise pumped into the dome.
The Colts have continually denied the accusations, and issued their strongest worded statement yet on Monday.
"We trust this will put an end to the ridiculous and unfounded accusations that the Colts artificially enhanced crowd noise at the RCA Dome in any way," the team said.
Patriots coach Bill Belichick, no stranger to controversy, did not discuss those allegations during his regularly scheduled news conference Monday. Instead, Belichick said he was more concerned with communication problems he said existed between Patriots coaches and Brady.
"Basically, we didn't have a coach-to-quarterback operation, so we had to signal in all of the plays, which is unusual, but that's the way it was," he said. "What all was going on, I can't tell you, but I can tell you that, from a functional standpoint, the coach-to-quarterback was basically useless."
The latest accusations add yet another chapter to this already heated rivalry.
There have been complaints about leaving the field at Gillette Stadium uncovered the night before games and contentions Pats defenders were illegally holding receivers downfield.
Now there's crowd noise, communication issues and even something as simple as a postgame handshake between Colts coach Tony Dungy and Belichick, who quickly walked past Dungy as Dungy attempted to speak with him Sunday.
Dungy downplayed the incident.
"Bill is fine, he's a good guy, that's the way he is win or lose," Dungy said. "He's just an intense guy out there. I wouldn't describe it any way other than what it is."