Sound Engineer's Pocket Book, 2nd Edition

5  Typical Noise Levels

The measurements given below must not be taken as definitive since there can be significant variations between different circumstances: for instance traffic noise can vary with the type and speed of vehicles, wear of bearings in industrial tools can alter the noise emission. Nevertheless the figures given are indicative of the approximate sound levels which might be likely in the stated conditions. Unless otherwise stated the measurements were made at 1 m from the noise source.

Source	dBA	Notes
Transport
Jet aircraft	140	At 30 m, take-off
Jet aircraft, small	120	At 150 m
Train, freight	99	Wagons at 12 m
Train, freight	96	Locomotive at 12 m
Train, high speed	95	At 12 m from track
Train interior ...