Evaluation of Fan Noise Loudness Using A-Weighted Sound Level and Zwicker's Model

In the modern world, the close interaction between man and machine requires that new product standards adopt stricter limitation on parameters that negatively affect humans. Small cooling fans, used in many business machines, often produce noise that may become an operational limitation. To limit noise produced by fans, an understanding of the human perception of the noise must be developed. Acousticians traditionally use the A-weighted decibel scale (dBA) to estimate perceived levels from measured data. However, a great deal of published work from Zwicker [1] indicates that the simple low frequency correction provided by the A-weighting inadequately represents the way in which people hear sound. This paper discusses the similarities and differences between two types of predictors of perceived sound level, Zwicker's loudness model and A-weighted sound level.