Durham School of Architectural Engineering and Construction


Date of this Version



©2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. www.ashrae.org. Reprinted by permission from ASHRAE Transactions, Vol 116, Part 2, 2010. This material may not be copied nor distributed in either paper or digital form without ASHRAE’s permission.


This project seeks to determine what relationship, if any, exists betweenbackground noise levels in elementary classrooms due to the building mechanicalsystems and student performance on achievement tests. Previous research inclassroom acoustics has clearly identified that lower background noise levelsresult in higher speech intelligibility which is crucial for the learning process;however, there is a lack of data correlating lower noise levels to improved studentachievement scores. For this study, background noise level measurements were madein 14 elementary schools in a public school system in Council Bluffs, Iowa, USA.The measurements were made in unoccupied classrooms with the central buildingmechanical systems activated. Second and fourth-grade classrooms were included inthe study, which typically contain 7 to 8 and 9 to 10 year-old students,respectively. The unoccupied noise levels measured in the analyzed classroomsrange from 36 – 50 dBA, none of which meets the background noise levelrecommendation of 35 dBA or less specified for classrooms in ANSI S12.60-2002(R2009). These measured background noise levels have been correlated toreading comprehension and math standardized achievement test scores from studentsin the surveyed classrooms. Poverty rates were used as a control variable for thecorrelation analyses to factor out some of the socio-economic differences among thestudents. ANOVA and regression analyses were also performed to determine iflearning for the younger and older students was impacted similarly by mechanicalsystem noise and what background noise level should be attained in classrooms tomeet state learning achievement goals. The results from this study show that, forthe elementary school system tested, lower student reading comprehension scoreswere significantly related to higher background noise levels from buildingmechanical systems.