A 2012 trade study projected that noise from existing open rotor technology would be 10–13 decibels quieter than the maximum noise level allowed by the Stage 4 regulations; the newer Stage 5 noise limits (which replaced the Stage 4 regulations for larger aircraft in 2018 and mirrored the ICAO Chapter 14 noise standard established in 2014) are more restrictive than the Stage 4 requirement by only seven effective perceived noise decibels (EPNdB), so current propfan technology shouldn't be hindered by the Stage 5 standards.