Not all birdsongs have the same effect on our ears, and certain sound characteristics seem to influence our preferences.
Researchers from the University of Tübingen played vocalizations from 123 European species to 84 adults. The sessions took place in a laboratory, in a controlled environment. Each participant had to rate how pleasant the sounds they heard seemed to them.
Male Eurasian blackbird (Turdus merula), the species whose vocalizations received the highest average rating in the study.
Photo: Andreas Trepte / Wikimedia Commons, CC BY-SA 2.5.
Wikimedia image
The researchers then compared these ratings with several measurable characteristics of the recordings. In particular, they studied the pitch of the sounds, their intensity and the range of frequencies used. The latter corresponds to the gap between the lowest and highest sounds present in a vocalization.
A pattern emerged from the results. Participants generally preferred vocalizations whose low and dominant frequencies were relatively high. Moderate intensity and a narrower frequency range were also associated with higher ratings. The combination therefore matters more than a simple opposition between high- and low-pitched songs.
The song’s internal variety also plays a role. Vocalizations displaying greater diversity in their sound organization were rated more favorably on average. The study establishes associations between several sound properties and human evaluations.
The differences between species are particularly telling. The Eurasian blackbird received the highest average rating, with 4.52 on the scale used. The barn owl was at the other end, with an average of 1.32. The experiment focused on specific recordings rather than all the possible sounds produced by each species.
Barn owl (Tyto alba), the species whose vocalizations received the lowest average rating in the experiment.
Photo: RAJIB.MTY / Wikimedia Commons.
One might think that bird experts appreciate birdsongs differently. Yet the data showed no significant effect of ornithology experience. However, people who said they valued birds more generally gave higher ratings to the vocalizations. Our relationship with the animal therefore also affects perception.
These results may be of interest for the management of green spaces. A park rich in birds does not necessarily produce the same soundscape as another hosting different species. The authors suggest considering the acoustic composition of bird communities, rather than just the number of species, when studying the sound quality of a place.
The study cannot, however, turn these characteristics into a universal recipe for a pleasant song. The participants were adults recruited in Germany, and the appreciation of a sound also depends on personal experiences. Future research could test whether the same preferences appear in other populations and in real environments, away from the laboratory.