The Relationship between Perceptual Dimensions of Fan Noise and Patterns of the Specific Loudness

Psychoacoustics

Fan noise is a typical component of environmental noise perceived by humans in every day situations. In order to enable a successful development of more pleasant fan sounds, it is desirable to understand and characterize the perceptually relevant aspects of fan noise beyond current technical measures like the dB(A).
The aim of this study is a determination of the perceptual dimensions of fan noise, an identification of the dimensions which are relevant for the (un-)pleasantness of fan noise and the development of (psycho-) acoustic parameters reflecting the most relevant perceptual dimensions. In a listening experiment, 35 different fan noises were rated by 45 participants using a semantic differential. The semantic differential consisted of 29 adjective scales covering evaluative items (like e.g. unpleasant - pleasant) and also descriptive items (like e.g. not humming - humming).
Based on two different factorial analyses of the fan noise ratings, six perceptual dimensions and five groups of sounds could be identified. The six perceptual dimensions describe how (I) pleasant, (II) humming/bass, (III) shrill, (IV) monotone, (V) reverberant and (VI) noise-like the fan sounds are. The five groups of sounds can be characterized as (A) unpleasant, (B) humming, (C) pleasant, (D) noise-like and (E) varied. It turns out that the pleasant and the unpleasant sounds can be mainly distinguished based on the first three perceptual dimensions. The group of pleasant sounds (C) is middling on the factor humming/bass and is not shrill, whereas the group of unpleasant sounds (A) is slightly humming and very shrill.
An analysis of the specific loudness according to the DIN 4563 standard reveals systematic differences between the three identified main groups of fan sounds (A) unpleasant, (B) humming and (C) pleasant which might allow to derive new psychoacoustic indexes tailored to the characterization of fan noises.