Auditory discrimination and identification of time of day for natural soundscapes

Following research on the auditory discrimination of natural soundscapes by human listeners [Apoux, Miller-Viacava, Ferrière, Dai, Krause, Sueur and Lorenzi (2023). J. Acoust. Soc. Am. 153, 2706], the present study assessed the ability of normal-hearing listeners to identify and/or discriminate the time of day (Dawn, Midday, Dusk, and Night) for soundscapes recorded in temperate and tropical forests. Identification was assessed using a single-interval four-alternative forced-choice task. Discrimination was assessed using a three-interval oddity task, where the listener was required to pick the odd one out. While identification of time of day was generally poor, discrimination was significantly above chance, indicating that listeners could hear some differences associated with the time of day, but could not effectively use those differences to assign the correct verbal label. The contribution of level, fine spectral, temporal envelope and temporal fine structure cues to discrimination was assessed. None of these cues appeared to be critical for time of day discrimination. Instead, it is suggested that listeners based their decisions on gross spectral cues, including aspects such as those related to ambient-noise spectral distributions.