The objectives of this program were to identify the prevalent sources of crushing and screening noise in portable and stationary plants, design retrofit noise control treatments for those sources, and field test control treatments under actual operating conditions. A survey was made to assess the variety of noise sources, to determine the worker exposure to those sources, and to identify possible constraints that should be considered in designing and installing retrofit controls. Retrofit noise control treatments designed included a primary crusher operator control booth; screen decks made of resilient cloth; screen feedbox impact pads; and rubber feed plates and chute lines, and noise attenuating curtains for a secondary crusher. A new primary crusher control booth was installed at one plant and the noise levels were reduced from 97 dba to 78 dba. Screen noise at two secondary crushing plants was reduced by 3 dba, and crusher noise at one of these plants was reduced by 5 dba. Noise levels at normal outside operator and cleanup locations were not significantly reduced in the second plant because of rapid wear of installed materials, but at the other plant the retrofit noise control materials displayed excellent wear characteristics.