A new study has found that the world’s finest yodellers aren’t from Austria or Switzerland, but the rainforests of Latin America. Published in the journal Philosophical Transactions of the Royal Society B and led by experts from Anglia Ruskin University (ARU) in Cambridge, England, and the University of Vienna, the research provides significant new insights into the diverse vocal sounds of non-human primates, and reveals for the first time how certain calls are produced. The researchers have discovered that special anatomical structures called vocal membranes allow monkeys to introduce “voice breaks” to their calls. These have the same rapid transitions in frequency heard in Alpine yodelling, or in Tarzan’s famous yell, but cover a much wider frequency range.