How animals holler

May 21, 2018, University of Utah

While humans can only broadcast about one percent of their vocal power through their speech, some animals and mammals are able to broadcast 100 percent. The secret to their long-range howls? A combination of high pitch, a wide-open mouth and a clever use of the body's shape to direct sound—none of which are factors that humans can replicate.

"Will humans ever be able to call to each other over long distances in an emergency situation, as wild-life has evolved to do well over millions of years?" asks Ingo Titze, director of the National Center for Voice and Speech at the University of Utah.

The research is published in the Journal of the Acoustical Society of America and was funded by the National Institute on Deafness and Other Communications Disorders.

Moving air efficiently

Animals produce sound by moving air from the lungs, through the throat, and out of the mouth. The slow-moving air has to be converted to rapid back-and-forth movement to produce sound. At each stage, some of that sound power is lost. Only about 10 percent of the aerodynamic power produced in the lungs makes it to the throat. And the soft tissues in the throat absorb sound further, Titze says. But then there's the radiation efficiency—the amount of sound that is transmitted out of the mouth.

It's this calculation that Titze and Anil Palaparthi, a doctoral student in biomedical engineering are introducing in this study. "We went back to mathematics that were available 100 years ago," Titze says. "We looked at a more modern way of computing it and came up with an efficiency formula."

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