Gibbons are the opera singers of the jungle. The small apes use the same technique to project their songs through the forests of southeast Asia as top sopranos singing at the New York Metropolitan Opera or La Scala in Milan.
That was the conclusion of research by Japanese scientists who tested the effect of helium gas on gibbon calls to see how their singing changed when their voices sounded abnormally high-pitched.
Just like professional singers, the experiment found the animals were able to change the shape of their mouth and tongue to make the higher sounds louder.
It is a skill only mastered by a few humans, yet gibbons are able to do it with little effort, according to Takeshi Nishimura from the Primate Research Institute at Kyoto University.
Singing is particularly important to gibbons, which use loud calls and songs to communicate across the dense jungle. These gibbon songs can be heard from more than a mile away. Primatologists (scientists who study apes, monkeys and other primates) call these exchanges “duets.”
Making gibbons sing on helium may sound strange, but Nishimura said it was a logical way to test how the animals controlled their voices when the vibrations in their voices moved higher.
“Using the helium environment, we can easily see how the resonance works and how the gibbon makes its loud pure-tone calls,” he said.
His team used a captive white-handed gibbon to record 20 calls in normal air and 37 calls in a helium-enriched atmosphere to show how the animals could consciously change their vocal cords.
Helium causes that distinctive high-pitched sound because sound travels much faster through the gas than through air.