Five sound level measuring instrument responses were compared in four plant noise situations. A sound level meter (SLM), an integrating sound level meter (LOSHA), a 25 dB crest-80 dB threshold dosimeter, a 15 dB crest-80 dB threshold dosimeter, and a 15 dB crest-90 dB threshold dosimeter were used in the study. All instruments were calibrated and maintained as recommended by the manufacturers and were tested in constant noise environments at moderate and high levels, at moderate background levels with moderate impact noise, and at low background levels with high impact noise. Experimentation was conducted in a plant environment designed to encompass various types of noise exposure actually found in industry. The results showed varying differences depending on noise levels between dosimeters with matching crest factors but with differing thresholds. The results showed no appreciable differences among instrument precision, dosimeter response at 25 versus 15 crest in impact noise areas, LOSHA meter response with dosimeter response at matching thresholds, SLM readings with 80 threshold dosimeter response, and LOSHA meter response at 80 threshold with SLM data.