Influence of the fundamental frequency and number of harmonics on preference judgements for fan sounds

Fan sounds are often heard in everyday life. Besides broadband noise, the sounds often contain one single or multiple tonal components, which can render the sound rather unpleasant and annoying. In this study, level adjustments for equal preference were measured in listening experiments for synthetic fan sounds compared to a fixed reference sound. The stimuli were based on two different background noises with one embedded single tone, or a multitone with eight partials. The tonal components had fundamental frequencies of either 80 or 240 Hz. All sounds containing tones needed level reduction to become equally preferred as the reference sound. The tonal configuration, as well as its fundamental frequency, did typically influence the effect. Additional level reductions for signals containing higher harmonics were necessary to reach equal preference compared to signals that contained only a single tone. For a fundamental frequency of 80 Hz, the additional level reductions were only 1.5 dB on average, for a fundamental frequency of 240 Hz up to 9.7 dB were necessary. The level reductions for equal preference were larger for sounds using a background averaged across real fan sounds compared to using bandlimited synthetic noise.