This study was made to find the effects of noise on the human body, to measure sound levels that exist in school power laboratories, and to design and evaluate the effectiveness of two noise control devices. An accurately calibrated testing device was used to measure sound levels in an attempt to determine if excessive noise exists in school power laboratories and to find the extent to which such noise can be reduced by shielding or enclosing the engine test area. It was found that noise has undesirable physical and psychological effects on the human organism. Sixty-two and one-half per cent of the engines tested registered sound levels above 90 dBA; even so, simple, inexpensive noise control devices do control the noise levels generated in the school power laboratories.