Descriptors of Sound From HVAC&R Equipment

A test was conducted to investigate how people describe HVAC&R equipment noise. Twenty-eight recordings and modified recordings were played to 42 subjects who wrote down descriptions as they heard the sounds. Subjects also rated these and 12 other sounds on an annoyance scale. The words used by subjects were categorized into 9 groups and the occurrences of the words within a group were counted for each sound. The results of the word analysis were compared to results of a sound quality metric analysis of the sounds, and to the results of the annoyance test. There was a high degree of correlation between the word scores and the corresponding metric values. The performance of linear models of metrics as predictors of annoyance was examined and loudness was the strongest contributor because of the large range of loudness used in the test. There were two significant outliers to the general trend of the predictions; these were sounds that were described by subjects as "sharp" and "high pitched". The results of this test are being used in the design of a semantic differential test to examine the relationship between sound characteristics and annoyance further.