ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aNS5. Advances in noise control for products other than aircraft.

William W. Lang

Phys. Dept., Box 539, Vassar College, Poughkeepsie, NY 12601

How much progress has been made in advancing the technology of noise control over the past quarter century? Different techniques of quieting have been applied to the many products that are grouped in the following broad categories: stationary noise sources, moving noise sources (other than aircraft), and specialized industrial machinery and equipment. For all products, the control of noise by engineering design is the goal. To arrive at estimates of progress, two subsidiary questions must be addressed. How is progress to be measured in quantitative terms? Recognizing that trade secrets and patented innovations may be involved, how is it possible to learn what progress has been made for the different classes of products? A key factor is that changes in functional technology may reduce the noise emissions as a desirable by-product; for example, ink-jet and laser printers are much quieter than impact printers. The estimates of progress in product quieting in terms of the reductions of A-weighted sound power levels range from 0 dB for leafblowers up to 50 dB for devices which 25 years ago required cooling fans for their safe and efficient operation, but today require none.