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 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.