Nicole Miller-Viacava, researcher and first author, has built a database of 11,000 natural soundscapes recorded in tropical, subtropical, boreal and temperate forests, a savannah and a desert, at different times of day and precipitation levels. This database, called Hearbiodiv and available upon request, is the result of international cooperation with teams of ecologists from several countries. The audio analyses conducted by Nicole Miller-Viacava have made it possible to characterise the statistical regularities of these natural soundscapes in terms of spectral and temporal modulations and have demonstrated that each habitat has a unique acoustic signature, strongly determined by the degree of biodiversity in the habitat. This initial finding is important because it demonstrates that natural soundscapes, despite their variability, are highly structured in the spectral and temporal domains.

This initial investigation was supplemented by a behavioural study. A group of naive listeners listened to each acoustic sample from the Hearbiodiv database with the task of detecting animal vocalisations (birds, insects, amphibians, mammals), animal actions (motion sounds) or geophysical sounds (wind, rain, rivers). The participants were consistent in their responses related to animal vocalisations, but much less so with regard to geophysical sounds and animal actions. Analyses of their responses highlight the use of distinct spectro-temporal perceptual templates between closed (forests) and open (desert and savannah) habitats, reflecting differences in sound propagation modes.

Through their variety, these perceptual templates demonstrate that, contrary to previous studies, humans do not rely solely on harmonicity (and tonality) and slow amplitude fluctuations to detect the presence of life in their immediate environment through hearing. Other cues (e.g. rapid fluctuations) are taken into account depending on the habitat. These templates could also guide the development of new methods for monitoring biodiversity inspired by the functioning of the human auditory system.`

Taken together, these results renew our understanding of the perceptual mechanisms involved in listening to the biological component of our sonic environment. 

MORE INFORMATION

• Ecologie auditive humaine - Wikipedia
• Christian Lorenzi

Miller-Viacava, N., Ferriere, R., Friedman, N. R., Mullet, T. C., Sueur, J., Willie, J. & Lorenzi, C. (2026, in press). Spectro-temporal modulation templates for human perception of animal vocalisations in natural soundscapes. Journal of the Acoustical Society of America.

Miller-Viacava, N., Apoux, F., Ferriere, R., Friedman, N. R., Mullet, T. C., Sueur, J., Willie, J. & Lorenzi, C. (2026). Modulation statistics of natural soundscapes. Journal of the Acoustical Society of America, 159, 1263–1289.