There is something truly beautiful about the sound of birds. Whether it is waking you from a deep sleep, or the backing sound of a gentle walk, birdsongs are an instant pick-me-up to your day. And now, scientists know exactly why.
A team of researchers asked people to listen to a collection of birdsongs, rating each one for how pleasant they were, then cross-referencing them with information about the call’s acoustic characteristics.
Using this information, the team of scientists identified key aspects that make some birdsongs seem more pleasant than others.
“You don’t have to be a ‘bird person’ to find bird sounds beautiful,” said lead author of the study Dr Nadine Kalb of the University of Tübingen.
“Being able to recognise birds by their appearance or song did not affect how people rated calls. This suggests that enjoyment of birdsong is connected to something more fundamental than just knowing what you are listening to.”
84 people were recruited and played short clips of 123 songs from common wild birds. Participants then had to rate each clip on a scale from one to five. Using this information, along with a measurement of the pitch, complexity and frequency of each song, the scientists were able to compare how beautiful each bird song was to the public.
Which birds sound the best?
The Beatles got it right, the blackbird song was considered the most pleasant. On the opposite end of the spectrum, a barn owl was considered the least pleasant.
Interestingly, the song of blackbirds has been found before to be highly restorative, helping people recover from mental fatigue and stress.
Across all of the different songs, a narrower bandwidth and greater complexity was perceived as the most pleasant. That means songs that don’t change much in pitch, but included more complicated tunes.
Interestingly, the songs that were deemed the most beautiful completely avoided a frequency where human hearing is more sensitive.
“We might be wired to prefer more variable sounds with moderate amplitudes and frequencies because they signal a safe, healthy, and restorative environment where we can relax,” said Kalb.
The team pointed out that, while this highlighted key points in our understanding of bird songs, there is still a lot they don’t know. Some birds call more frequently than others, and this could affect our perceptions of their pleasantness.
In the future, they hope to expand their research further, better understanding these bird songs and how humans interpret them.
