Date of Graduation
Statler College of Engineering and Mineral Resources
Industrial and Managements Systems Engineering
Noise enclosures are an important tool in reducing noise exposures. Holes in enclosures are known to reduce the effectiveness of such enclosures. There are methods to predict the effects of openings, but those methods are largely untested in real enclosures. This study investigated the effects of hole size (0%, 0.024%, 0.379%, 0.675%, 1.492%,and 5.063%) at a distance of 5 feet (1.524 m) in a 96 inch (2.46 m) x 37 inch (0.94 m) x 31 inch (0.79 m), 3/4 inch plywood enclosure with a noise source centered in the box and the openings centered on one long face of the box. The enclosure was tested inside a relatively live room (Approx. R = 3000 ft2).;Results showed that no predictive model accurately predicted behavior. As expected, noise reduction (NR) values varied inversely with opening areas. However, the relationship was not monotonic, possibly due to resonance frequencies inside the box. In fact, spikes in NR and values occurred at the wavelengths corresponding to 500 Hz. At 4000 Hz, it was observed that even a small opening area of 4 sq.inch reduced the insertion loss by 14 dB. On the other hand, at 500 Hz small openings did not significantly affect the Insertion Loss.
Hegde, Amit Damodar, "Effect of opening size on the effectiveness of a noise enclosure on the side facing the opening" (2005). Graduate Theses, Dissertations, and Problem Reports. 1597.