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Word of the Week: Tympanum
August 07, 2020 by Magali Meagher

Welcome to Word of the Week! Stay tuned for a new word each Friday to amp up your nature vocabulary!

Photo by Andrew Yee

Tympanum [TIM-puh-nuh m](noun): The ear opening in many amphibians, reptiles and insects (in amphibians, normally covered by a circular membrane).

Which creature in the wetland makes the best drummer? Ba-dum-bum… The one with a tympanum! Amphibians like frogs, some reptiles and many insects use this protective circular patch of skin stretched over a ring of cartilage (just like a drum) to transmit sound waves to the middle and inner ear for interpretation by the brain. For a frog, the tympanum allows it to hear both in the air and below the water. What an important tool for sensing prey, locating predators and finding potential mates!

Don’t be fooled, this lack of an outer ear belies a very exciting internal relationship between the sound the frog makes and the sound it hears. In some species of frog, the size of the tympanum as well as the distance between its two eardrum membranes is relative to the frequency and wavelength of the species male call. To create this call, the lungs produce an air pocket in the vocal sac emitting sound that can be heard from kilometers away! You might wonder how the frog can handle hearing such a loud sound!

The interconnected air route between the tympanum and the lungs protects the frog from damage to the eardrum since the air pressure coming from inside the frog’s body is dampened by the tightly pulled membrane of the tympanum.

If you are walking near one of the ponds in High Park in the coming weeks, you may hear a sound reminiscent of a rubber band being snapped or banjo string being plucked. If you try to imitate it, I wonder if you’ll get a response?!

References:

http://online-field-guide.com/glossary.htm#Anatomy%20-%20T

https://www.burkemuseum.org/collections-and-research/biology/herpetology/all-about-amphibians/all-about-frogs

https://animals.mom.me/sensory-organs-found-frogs-head-3278.html

https://acoustics.org/pressroom/httpdocs/swa9501.html

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