Usage of acoustical material to reduce the shop planer operating and surfacing noise to eighty-five decibels of audible sound revealed that the acoustical treatments would reduce the noise level in the shop. Eighty-five decibels of sound was the established federal safety level at which continuous exposure of the unprotected ear to the noise would not cause decibel deafness.

The sound reference source machine was used to establish the shop as a standard for the obtained measurements, and the Precision Sound Level Meter was employed to measure the decibel ratings. An acoustical hood, and an acoustical chamber were the two major treatments utilized to reduce the planer operating and surfacing noise. Selected softwood, Douglas fir, and selected hardwood, white oak, stock samples were surfaced by the planer to obtain the decibel ratings. The measurements of sound varied as to the type of wood samples, decibels of audible sound, and decibels of sound at various octave band frequencies.