They produce an extremely wide range of sound frequencies. It far exceeds that of vocalists such as Mariah Carey, Axil Rose or Prince. The sound range of the bats is unusual.
It was filmed for the first time directly how they produce their extraordinary range of sounds. The study is in the journal ‘PLoS Biology’. Bats use the same technique as human death metal singers. Or the members of the Tuva people of Siberia and Mongolia who sing with their throats.
Singing bats
The University of Southern Denmark, led by Professor Coen Elemans, did the study. They saw what happens in the larynx of a bat when it produces a sound.
“They can make low-frequency calls, using their so-called “false vocal cords.” Just like human death metal singers do,” they explain. They are so called because they look like vocal cords. But they are not used in normal human speech and singing. Only death metal growlers and throat singers in some cultures around the world use their false vocal cords like bats.
Bats emit grunts when they enter or leave a densely populated roost. It uses its false vocal cords to produce low sounds in the range of 1 to 5 kHz.
High speed
“Some look aggressive. Others may be an expression of annoyance, and others may have a very different function. We don’t know yet,” they say. When bats hunt insects in the dark, they use echolocation. They send out very short, very high-frequency calls. And they listen for echoes reflected from objects in the environment to find and capture insects.
For the first time it is known how bats are able to make their echolocation calls. They do so by vibrating very thin vocal membranes. These are structures that we humans also had, lost in our evolution.
“To show their vibrations we had to film at extremely high speeds. Up to 250,000 frames per second. According to the research team, the normal vocal range of a bat spans 7 octaves. “This is extraordinary. Most mammals have a range of 3 to 4, and humans about 3. The sound range of bats is remarkable.”
