I collected measurements of real-world decibel levels on a handful of commercial flights. Here they are. All seats, except one, were positioned in-front of the engines, and measurements were taken once we reached cruising altitude. The leading number is the decibel level.
82 - Airbus 319, row 12
82 - Boeing 767, row 6 intl business class
83 - Boeing 757, row 6 first class
84 - Boeing 737, row 8
77 - Airbus 320, row 10
88 - Airbus 319, row 31
75 - Airbus 320, row 3 first class
85 - Boeing 757, row 6 first class
84 - Boeing 737, row 10
92 - Boeing 757, row 3 first class
85 - CRJ200 , row 8
93 - Dash 8-300 (prop), row 10
80 - Boeing 787, row 2 first class
82 - Boeing 757, row 3 first class
84 - Boeing 737, row 8
84 - Boeing 787, row 5 first class
