A PRACTICAL APPROACH TO TRUCK NOISE REDUCTION

An approach is described for reducing the drive-by noise of a 14-liter diesel-engined truck which involves a combination of conventional noise reduction techniques. The combustion and mechanical exciting forces within the engine are respectively lowered by turbocharging and low-noise pistons, coupled with a small reduction in the rated speed. The resulting noise is largely attenuated by employing simple shielding attached with isolation mounts to form a tunnel around the engine. A reduction of drive-by noise from 92 1/2 dBA to 82 dBA has been demonstrated with this approach. A level of 80 dBA was achieved with additional silencing and shielding of the non-engine noise sources. A method is appended for calculating the radiated combustion and mechanical noise levels from an engine.