Pleasantness Judgements of Air Diffuser Noise and Their Relation to Psychoacoustic Parameters

This study investigates the subjective pleasantness of airflow noise generated by five air diffusers used in building ventilation systems and how it can be modelled by psychoacoustic parameters. Recordings were made in a hemi-anechoic chamber at various volume flow rates and subsequently auralised in a simulated room for a listening experiment. Thirty normal hearing participants compared the air diffuser stimuli using a paired comparison method across five blocks defined by equal sound pressure levels (35, 40, 45 dB(A)) or equal volume flow rates (400, 600 m³/h). Additionally, psychoacoustic parameters were analysed for all stimuli. Results reveal differences in pleasantness between air diffuser stimuli in all blocks. While participants were able to determine consistent rank orders individually, a concordance analysis indicated only limited agreement across participants, except for the 600 m³/h block where agreement was comparatively higher. Regression analyses revealed that both loudness and sharpness exhibited negative associations with subjective pleasantness, indicating that higher values of these psychoacoustic parameters reduced pleasantness. Combining these two descriptors slightly improved model performance compared with loudness alone, at the cost of increased model complexity. These findings highlight that even when sound pressure level or volume flow rate is held constant, subjective evaluation differences between air diffuser noises persist and can be explained by psychoacoustic factors. The study concludes that loudness is the dominant descriptor of subjective pleasantness of air diffuser noise, while sharpness may provide additional information. Therefore loudness and sharpness should be considered in future product assessment and design.