The objective of this program was to investigate, design, develop, and demonstrate noise control techniques that could be designed into new jumbo drills. Techniques used in this program were an isolated drill guide, damped acoustical enclosure, standard mufflers, and a specially designed silencer for the air egress of the enclosure. Conventional mufflers were used for the feed and rotational motor exhausts. The Ingersoll-Rand VL-120 drill with a standard udm-14 slide were used as the test and development subjects. An enclosure was developed that encompassed the drill and slide, and at the same time did not interfere with performance or ease of operation. Standard construction materials were utilized throughout the program. Sound pressure levels of the unit as-received were 113 dba at the operators position, and 101 dba at a 7-meter location. After all of the noise reduction techniques had been implemented, the sound pressure levels were 102 dba at the operators position, and 87 dba at a 7-meter location. A conceptual design for an improved quiet drill is also presented.