Getty Images

Two weeks into a season largely without in-person fans, the NFL has changed its stadium audio policy, allowing teams to crank up the volume on fake crowd noise beginning in Week 3. As NFL Network's Tom Pelissero reported Friday, the league has informed clubs that any stadium housing fewer than 2,500 fans can now play pre-recorded game-day audio at up to 80 decibels.

The NFL previously required all stadiums to play team-specific audio that it distributed to each club, with a maximum volume of 70 decibels. For comparison, a 70-decibel sound is equivalent to the audio levels of a vacuum or passenger car, whereas 80 decibels are more like the audio levels of a food blender or freight train. All in all, the decibel increase will essentially allow teams to pipe in twice as much noise on game days.

The decibel level must be selected and confirmed with the NFL 90 minutes before kickoff, per Pelissero, and must remain the same from kickoff through the end of the game, regardless of which team has the ball. Stadiums that can hold 2,500 or more fans, however, can now opt out of using pre-recorded audio altogether, instead relying solely on in-person crowd noise.

To be clear, these changes and in-stadium decibel limits do not apply to broadcast noise. TV audio, including pre-recorded crowd noise, is controlled separately for this year's NFL games, per Pelissero, which is why certain stadiums appear to get louder for home-team touchdowns even though the stadium is either empty or confined to consistent sound levels.