McGill University researchers have identified "universal" vocal patterns across hundreds of bird species and found that many of the same patterns also appear in human song and speech from cultures around the world. The patterns include small pitch intervals, regular and predictable rhythms, and phrase-final elongation, in which the last utterance in a phrase tends to be longer than the others.
The study, which compared bird vocalizations with a global collection of human speech and songs, could be used to better understand the mechanisms of vocal production and auditory processing across species, the researchers said.
"We propose that shared acoustic patterns among birds and humans may be due to common vocal production mechanisms or biases," said Logan James , first author and Postdoctoral Fellow in the Department of Biology. "For example, birds and humans are unlikely to dramatically change pitch from one note to the next ('small pitch intervals') because it is difficult to do. Phrase-final elongation in birds and humans could be due to breathing patterns when we vocalize."
This study is the first to compare vocal patterning in birdsong that includes both species of birds that learn their songs and species whose songs are innate. It is also the first to include a direct comparison of these patterns to a global repository of human speech and songs.
Songs from around the world
The researchers analyzed recordings from more than 350 bird species and then used publicly accessible databases of human vocalizations to compare bird vocal patterns with speech and song in 52 languages .
The researchers analyzed the vocalizations of four groups of birds: songbirds and hummingbirds, as well as two closely related groups, suboscines and nightjars. The team downloaded recordings from xeno-canto , a citizen-science website that gathers wildlife sounds worldwide. They then manually annotated the files, resulting in about 70,000 vocal units for analysis.
"Songbirds, hummingbirds and parrots are 'vocal learners,' just like humans, meaning that they learn their vocalizations by imitating others," explained Jon Sakata, senior author and Professor of Biology. Suboscines and nightjars are non-vocal learners, meaning their vocalizations are innate.
Because human speech and song are learned, the team predicted that the songs of vocal-learning birds might share stronger similarities with human vocalizations than would the songs of non-learning birds. However, they found very little evidence to support that hypothesis.
"Given the similarities between all these groups of birds to humans, we hope this research will inspire scientists to investigate groups of birds that have historically been overlooked: namely, birds that do not learn their vocalizations," Sakata said.
About the study
" Pervasive patterns in bird songs resemble those in human speech and song and are independent of vocal learning ," by Logan James, Kendra Oudyk, Maria I. Pescaru, Erin M. Wall, Yining Chen, William D. Pearse and Jon T. Sakata, was published in Science.
The study was funded by the Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec - Nature et technologies, Fonds de recherche du Québec - Santé and the McGill University Centre for Research on Brain, Language and Music.
