The influence of different roughness metrics on noise discomfort in the aircraft cabin.

Acoustic roughness is a psychoacoustic metric frequently employed to characterize the discomfort or unpleasant sensations associated with the fast fluctuation features of noise. Generally, higher roughness values are thought to be associated with increased discomfort. However, contradictory phenomena have also been observed, e.g., the recent study [Huang, Lv, Ni, and Jiang, J. Acoust. Soc. Am. 154(4), 1963-1976 (2023)] found that the discomfort was predominantly influenced by loudness and exhibited a negative correlation with roughness for the aircraft cabin noise. To further investigate the influence of roughness metric on noise discomfort, two groups, each comprising 48 participants, rated the discomfort caused by aircraft cabin noise and amplitude-modulated (AM) sounds with modulation frequencies in the 10-140 Hz range, respectively. The discomfort values of aircraft cabin noise exhibit an insignificant correlation with Zwicker roughness metric (r = 0.159, p > 0.05) and a significant negative correlation with Sottek roughness metric (r = -0.640, p < 0.01). By measuring discomfort values of AM sounds, a modulation-frequency-dependent weighting curve was established. The roughness values, adjusted by replacing the weighting curve in the Sottek roughness model, displayed a significant positive correlation with discomfort values (r = 0.713, p < 0.01). This indicated that the modified roughness metric can directly represent the adverse effect of rough characteristics of noise on comfort.