During the winter, most sawmills equipped with a planing mill use special hammers to separate wood boards that have frozen together. Made partly of steel and activated by pneumatic cylinders, these devices produce sound impacts as high as 130 dB. They are therefore a source of considerable noise. At the request of the labour-management committee of the integrated noise intervention program in sawmills, the researcher will develop and validate an approach to reduce appreciably this very high noise level. The board hammers thus modified can be introduced into all sawmills that use such equipment.