Loudness- and preference-equivalent levels of fan sounds at different absolute levels



In daily life, fans are a common and often unwanted noise source. The sound pressure level in dB(A) is often not sufficient to characterize their unpleasantness and level adjustments would be needed to compensate this shortcoming.

In this study, listening experiments were conducted to determine loudness- and preference-equivalent levels of 19 different fan noise stimuli. For this purpose, the level of each stimulus was varied with an adaptive procedure until it was equally loud (loudness task), or equally preferred (preference task) as a common reference noise with a fixed level of 75 dB(A).

This study repeats an earlier similar study, with a lower reference level of 60 dB(A) and using a larger set of stimuli. The present results are in broad agreement with the results of the prior study, supporting the stability of the matching procedure. Apparently, level adjustments (penalties) derived from such experiments do not change when stimulus levels are increased by 15 dB.

Based on the new results, an existing model developed with a 60 dB(A) reference, can be expanded to also predict preferences for sound sources up to 75 dB(A). Further experiments with a reference level of 45 dB(A) will complement the data to lower levels.