Credit: Edward J. Walsh, Boys Town National Research Hospital.
An Amur or Siberian tiger roars, producing what is known as a long-distance advertisement call. A new study of vocal folds taken from six deceased tigers and lions shows that the frequency of their roars is determined by the shape of their vocal folds and by the ability of their vocal folds to stretch and shear, not by nerve impulses from the brain. The study was performed by scientists from the National Center for Voice and Speech at the University of Utah and University of Iowa, and the Boys Town National Research Hospital in Omaha.