Noise in army weapons systems, such as tracked art-iored vehicles increases detectability of our forces, reduces effectiveness by requiring cut back or shut down of equipment to reduce noise, reduces or eliminates the prospect of covert operation and reduces crew effectiveness in areas of high noise levels. Additional reductions in noise are required over what conventional methods of noise reduction are providing. Active noise and vibration cancellation have the potential to reduce both priMary and secondary acoustic emissions to levels below the thresholds of sound ranging and detection equipment in use today. This project will accurately survey and Map sound intensity levels of a typical combat vehicle. Teiis Mapping will identify and characterize sound sources, level and spectral characteristics. these source will be catalogued and evaluated for corrective action. An electronic muffler will be designed, installed and tested on the bradley fighting vehicle diesel engine exhaust. The purpose of this system is to reduce exhaust noise without adding back pressure on the engine. Nose reductions from 10 db to 25 db have been experienced on gasoline and diesel engine exhaust with the electronic muffler.
