Can human listeners label and discriminate natural soundscapes based on diel acoustical patterns?

A previous study reported that human listeners can discriminate natural soundscapes with a high sensitivity and that they appear to base their decision on cues related to biological sounds and environment acoustics when discriminating habitats [Apoux et al., J. Acoust. Soc. Am. 153, 2706 (2023)]. The present study replicated and extended these findings while focusing on the sensitivity to diel acoustical patterns. Twenty-five listeners were asked to discriminate but also identify natural soundscapes recorded during a one-year period in a temperate forest at four distinct and identifiable moments of the day (Dawn, Midday, Dusk, or Night). In one experiment, stimuli were restricted in the audio frequency domain or noise vocoded to, respectively, assess the contribution of spectral and temporal cues to moment of the day discrimination. Overall, identification performance was poor, but discrimination was well above chance, suggesting that human listeners can derive some global properties of soundscapes associated with the time of the day, but struggle to assign these properties to the correct moment. The filtering data indicated that temporal cues and spectral details are not critical for moment of the day discrimination. Like habitat discrimination, listeners may rely primarily on gross spectral cues.