Psychological and physiological evaluations of time-varying noises produced by air conditioners

Abstract

Air conditioners are widely used in buildings to maintain thermal comfort for long time. Air conditioners produce sounds during operation, and air conditioners are regarded as one of the main noise sources in buildings. Most sounds produced by the air conditioner do not fluctuate over time and sound quality of the steady sounds produced by the air conditioner have been evaluated. However, air conditioners sometimes produce time-varying noises. Customers criticizes such noises are annoying when they sleep and they spend time quietly in the living room. The aim of this study was to determine the factors that significantly influence the psycho-physiological response to the time-varying noises produced by air conditioners. We assessed the A-weighted equivalent continuous sound pressure level (LAeq) and factors extracted from the autocorrelation function (ACF). Subjective loudness, sharpness, annoyance, and electroencephalography (EEG) were evaluated. Relationships between psychological and physiological responses and physical parameters, LAeq, the ACF factors, and their standard deviation, were determined. The LAeq and peak of the first maximum peak of the ACF were identified as significant factors for the time-varying noises.