Anglia Ruskin University researchers help uncover what makes monkeys the world’s best yodellers

Think the world’s best yodellers hail from Austria or Switzerland? Wrong. You’ll find them in the rainforests of Latin America.

Researchers at Anglia Ruskin University (ARU) and the University of Vienna have found that vocal membranes in the throats of non-human primates enable them to introduce ‘voice breaks into their calls’.

These occur when monkeys switch sound production from the vocal folds to the vocal membranes, which are extremely thin and sit above the vocal folds in the larynx.

The calls produced possess the same rapid transitions in frequency heard in Alpine yodelling, but over a frequency range five times greater than humans can achieve.

And while human yodels typically span one octave or less, New World monkeys are capable of exceeding three musical octaves.

Senior author Dr Jacob Dunn, associate professor in evolutionary biology at ARU, said: “This is a fascinating example of how nature provides the means of enriching animal vocalisation, despite their lack of language.

“The production of these intricate vocal patterns is mostly enabled by the way the animals’ larynx is anatomically shaped, and does not require complex neural control generated by the brain.”

Lead author Dr Christian T Herbst, of the Department of Behavioural and Cognitive Biology at the University of Vienna, added: “Our study shows that vocal membranes extend the monkey's pitch range, but also destabilise its voice. They may have been lost during human evolution to promote pitch stability in singing and speech.”