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

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 Leq 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 Leq. 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 Leq 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 Leq in air-conditioned offices was determined within the range of 45-70 dBA and the ‘optimum’ noise level La/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 Leq in air-conditioned offices elsewhere.