Lions' and tigers' fearsome roars are due to their unusual vocal cords, according to a study published in the Nov. 2 issue of the online journal PLoS ONE. The authors report that the big cats' vocal cards have an odd square shape and can withstand strong stretching and shearing. That shape "makes it easier for the tissue to respond to the passing airflow," allowing louder roars at lower lung pressure, says University of Utah researcher Tobias Riede, one of the researchers involved in the project.
These findings contradict a theory that lions roar deeply because the vocal folds are heavy with fat. Instead, the researchers speculate that the fat gives the vocal folds their square shape (as opposed to the more traditional triangular vocal folds found in most species), and may cushion the vocal folds and provide repair material when they are damaged.
"If you understand how vocal folds are structured and what effects that structure has on vocal production, then it could help doctors make decisions on how to reconstruct damaged vocal fold tissue" in people such as cancer patients, singers, teachers, coaches and drill sergeants, Riede says.
Citation: Klemuk SA, Riede T, Walsh EJ, Titze IR (2011) Adapted to Roar: Functional Morphology of Tiger and Lion Vocal Folds. PLoS ONE 6(11): e27029.doi:10.1371/journal.pone.0027029
Financial Disclosure: Funding for this work was provided in part by National Institutes of Health (NIH) Grants R01 DC008612, R01 DC04390, and 1R01 DC010275, and National Science Foundation (NSF) Grant 0823417. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interest Statement: The authors have declared that no competing interests exist.
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