FEASIBILITY STUDY OF NOISE CONTROL MODIFICATION FOR AN URBAN TRANSIT BUS

An investigation has been conducted to determine the feasibility of reducing exterior acoustic noise produced by an urban transit bus. The noise characteristics of the bus were studied and a number of noise-reducing modifications were designed to attack the principal sources. The modifications included an experimental radiator fan, muffling devices for the engine air inlet and exhaust systems, and a partial enclosure for the engine compartment. Noise tests were performed on the unmodified bus and on the bus equipped with all modifications. Several tests were made with one modification removed each time to determine its individual contribution. A-weighted sound level measurements and octave-band frequency plots are presented to show the effect of the individual noise-reducing modifications. /Author/