SALT LAKE CITY, Nov. 2, 2011 When lions and tigers roar loudly and deeply terrifying every creature within earshot they are somewhat like human babies crying for attention, although their voices are much deeper.
So says the senior author of a new study that shows lions' and tigers' loud, low-frequency roars are predetermined by physical properties of their vocal fold tissue namely, the ability to stretch and shear and not by nerve impulses from the brain.
"Roaring is similar to what a baby sounds like when it cries," says speech scientist Ingo Titze, executive director of the National Center for Voice and Speech, which is administered by the University of Utah. "In some ways, the lion is a large replica of a crying baby, loud and noisy, but at very low pitch."
The study of lion and tiger vocal folds and how they produce roaring vocalizations used by big cats to claim their territory was set for publication Wednesday, Nov. 2, in the Public Library of Science's online journal PLoS ONE.
While the comparison was not part of the study, Titze says a baby "cries to have people come to help it. The lion uses similar attention-getting sound, but mainly to say, 'I am here, this is my territory, get out of here.'"
"In both cases, we hear loud, grating sounds that grab people's ears. When a baby cries, the sound isn't pretty. The sound is basically rough. The vibration isn't regular."
The same is true of roars by lions and tigers, and, like babies, their vocal folds (commonly called vocal cords) are "very loose and gel-like" and vibrate irregularly to make roars sound rough, Titze says. The main difference: Babies cry at a high-pitched frequency, while big cats have a low-frequency roar.
Roaring Frequency Dictated by Structure of Vocal Folds
The new study's key finding is that lions and tigers can roar loudly and deeply because their vocal folds have a flat, square shape and
|Contact: Lee Siegel|
University of Utah