## Graduate Theses, Dissertations, and Problem Reports

### Insertion loss of a simple plywood noise enclosure

Summer

2012

Thesis

MS

#### College

Statler College of Engineering and Mineral Resources

#### Department

Industrial and Managements Systems Engineering

Steve Guffey.

#### Abstract

Noise enclosures are used to reduce noise exposures to the employee. Some problems with commercial noise enclosures is they tend to be expensive and often provide much more insertion loss (IL) than is truly needed. The two studies described here tested the effectiveness of a simple plywood noise enclosure with a size of 75 cm x 75 cm x 75 cm. To determine the IL of the enclosure an OROS OR 38 noise analyzer was used in conjunction with eight PCB piezotronic microphones located at four and eight feet from the source perpendicular to each vertical side of the enclosure.;Study One tested the effects of insulation coverage (Insulation), measurement distance from sound source (Distance), and direction in the horizontal plane (Microphone Location) on the IL of the enclosure when there were no holes in the enclosure. The results of Study One showed that the bare enclosure (0% insulation) provided a 6.9 dBA average IL. When the inner surfaces of the enclosure were covered with 50% and 83% of Insulation coverage, the IL values were 10.2 and 11.0 dBA, respectively.;Study Two tested the conditions listed in Study One as well as the effects of adding Hole Diameters of 2" and 4" at different times. It also included rotating the enclosure so the Hole Direction was either facing 0° or 180° from the original orientation. The results of Study Two showed that the average IL of the enclosure was reduced by 0.8 dBA when there was a 2" hole in the enclosure and by 1.7 dBA when there was a 4" hole in the enclosure.;The most important conclusion reached from the two studies was a simple noise enclosure can be constructed of plywood and it will be effective to some degree even if there all holes in it. The minimum IL this enclosure produced was 5.3 dBA when there was a 4" hole in one side. In many cases this would be sufficient enough to reduce a company underneath regulatory standards.

COinS

#### DOI

https://doi.org/10.33915/etd.3332