A new study has 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 findings could help identify the biological mechanisms underlying vocal production and auditory processing of communication that are common to humans and other animals.
These shared patterns include small pitch intervals, regular and predictable rhythms, and phrase-final elongation, where the last sound in a phrase tends to be longer than others. Logan James, first author from McGill University, suggested these similarities may stem from common vocal production mechanisms or biases, such as the difficulty in dramatically changing pitch between notes. Phrase-final elongation could be linked to breathing patterns during vocalisation.
This research is the first to compare vocal patterns across bird species that learn their songs and those whose songs are innate, and the first to directly compare these with a global repository of human speech and songs. The team analysed recordings from over 350 bird species and used publicly accessible databases of human vocalizations from 52 languages.
Recordings were downloaded from xeno-canto, a citizen-science website, and manually annotated, yielding approximately 70,000 vocal units for analysis. The study included songbirds, hummingbirds, suboscines, and nightjars. While researchers predicted that vocal-learning birds (like songbirds, hummingbirds, and parrots) might show stronger similarities to human vocalizations than non-learners, the study found little evidence to support this hypothesis.
Professor Jon Sakata, senior author and professor of biology at McGill University, stated that given the similarities observed across bird groups and humans, the research hopes to inspire further investigation into bird groups that have historically been overlooked, particularly those that do not learn their vocalizations.
