Durham School of Architectural Engineering and Construction


Date of this Version



©2005, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. www.ashrae.org. Reprinted by permission from ASHRAE Transactions, Vol 111, Part 1, 2005. This material may not be copied nor distributed in either paper or digital form without ASHRAE’s permission.

2005 ASHRAE Winter Meeting Transactions, Orlando, FL, 111, pt. 1, 684-692.


A number of indoor noise criteria systems are used to quantify the background noise in a built environment, including Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC Mark II), A-weighted Equivalent Sound Pressure Level (LAeq), and others. An on-going debate exists in the acoustical community over which criterion is the most appropriate to use in the variety of ambient noise situations encountered. In an effort to quantitatively support the use of individual criterion, this project subjectively correlates these various criteria with human task performance and perception. Eleven subjects participated in a pilot study by completing typing and proofreading tasks, as well as subjective ratings of loudness, annoyance, and spectral quality. Results show that there were no significant differences in productivity scores among the 12 noise exposures tested; however, significant relationships were found between indoor noise criteria predictions of level and subjective perception of loudness and annoyance. In this study, RC and RC-Mark II were found to be the most correlated with level perception, although NC, NCB, and LAeq were also strongly correlated. Additionally, interesting relationships were found between subjective perceptions of rumble or roar and criteria predictions of such. The authors are in the process of extending the pilot study to more subjects, as well as examining the effects of tonal and fluctuating background noise spectra on criteria predictions.