A method of assessing the acceptability of noise levels in air-conditioned offices

Abstract

This study examined the acceptable noise level in an office environment by interviewing 422 occupants about the aural environment being perceived in 61 air-conditioned offices in Hong Kong. The survey samples covered different types of building and prevalent mechanical air supply system. In particular, the measured equivalent continuous noise level L_eq in the offices was chosen as an indicator and correlated with the subjective responses from occupants on a visual analogue assessment scale and a dichotomous assessment scale. The results showed that this acceptability was significantly influenced by the office noise level and it would be correlated with a logistic regression model. A satisfaction criterion of the noise level could be evaluated from the frequency distribution of the occupants’ response at certain L_eq. In addition, the proposed satisfaction criterion of aural comfort in current design practice was confirmed by the survey samples: an indoor environment with an equivalent continuous noise level L_eq of 57.5 dBA would be adopted as a design criterion for some offices. Practical application: The neutral criterion for aural comfort indicated by the equivalent continuous noise level L_eq in air-conditioned offices was determined within the range of 45-70 dBA and the ‘optimum’ noise level L_a/57.5 dBA to be maintained in an office was determined from the survey. This study provides a template for applying a statistical frequency analysis and logistic regression model to examine the ‘optimum’ criteria for aural environment indicated by equivalent continuous noise level L_eq in air-conditioned offices elsewhere.

Get full access to this article

View all access options for this article.

References

Goldman RF. Extrapolating ASHRAE's comfort model. HVAC&R Research 1999;5:189-194.

Haghighat F , Donnini G. Impact of psycho-social factors on perception of the indoor air environment studies in 12 office buildings. Building and Environment 1999;34:479-503.

Lomonaco C , Miller D. Environmental satisfaction, personal control and the positive correlation to increased productivity. Johnson Controls 1997.

Leventhall HG , Wise SS. Making noise comfortable for people. ASHRAE Transactions 1998; SF-98-4-3.

Tang SK . Performance of noise indices in airconditioned landscaped office buildings. J. Acoustical Soc. Am. 1997;102:1657-1663.

Beranek LL. Criteria for office quieting based on questionnaire rating studies. J. Acoustical Soc. Am. 1956;28:833-852.

Beranek LL. Balanced noise criterion curves, BNC. J. Acoustical Soc. Am. 1989;86:650-664.

Kosten CW , van Os GJ. Community reaction criteria to external noise. National Physical Lab. Symptom. No. 12. London: Her Majesty's Stationery Office. 1962:373-387.

Beranek LL , Blazier WE , Figwer JJ. Preferred noise criterion (PNC) curves and their application to rooms. J. Acoustical Soc. Am. 1971;50:1223-1228.

10.

Blazier WE. Revised noise criterion for application in the acoustical design and rating of HVAC systems. Noise Control Eng. J. 1981;162:64-73.

11.

Stevens SS. Calculation of the loudness of complex noise. J. Acoustical Soc. Am. 1956;28:807-832.

12.

Zwicker E , Flottorp G , Stevens SS. Critical band width in loudness summation. J. Acoustical Soc. Am. 1957;29:548-557.

13.

Tang SK , Burnett J , Poon CM. Aural environment survey in air-conditioned open-plan. Building Serv. Eng. Res. Technol. 1996;17:97-100.

14.

Wong LT , Leung LK. Minimum fire alarm sound pressure level for elder care centres. Building and Environment 2005;40:125-133.

15.

Freund RJ , Wilson WJ. Regression analysis: statistical modeling of a response variable. Academic Press, 1998.

16.

Brager GS , De Dear RJ. Thermal adaptation in the built environment: a literature review. Energy and Building 1998;27:83-96.