| Abstrakt: |
The noise of chain saws powered by internal-combustion engines depends on the relative strengths of four major sources; engine exhaust and intake, noise radiated from the structure associated with engine operation (so-called 'mechanical' noise), and noise associated with the cutting process. The prospects for developing low-noise, high-performance saws have been explored by rank ordering the source strengths and examining the potential for reducing the sound pressure produced by the most significant source, or sources, at each frequency. At the present state of development, a further reduction in the noise at the operator's ear of approximately 5 dB can be expected by improving the exhaust and intake mufflers of a typical 3-kW saw, but the A-weighted sound level will remain in excess of 100 dB. Control of the mechanical noise will be required to reduce the A-weighted sound level experienced by the operator to 90 dB, within the constraints of minimal increases in weight, size, and cost, and maintenance of mechanical efficiency. [ABSTRACT FROM AUTHOR] |
