Bats have an amazing sense of hearing and can detect sounds far above the range of human hearing. These high pitched sounds are called ultrasounds. Even more amazing, bats use the echoes of their own sounds to navigate as they fly. This ability is called echolocation. Bats can direct their cries very precisely, in the same way that you can point a flashlight to shine a narrow beam of light. They send out streams of high-pitched sounds and listen for echoes bouncing off objects around them. It is like having a built-in radar system that uses sound instead of radio waves to “see” objects. By listening to these echoes they can learn about the texture and shape of an object as well as its size and location. They may even be able to tell which insects are good to eat and which are not.
Demonstrating how big ears help bats hear well (photo by Richard Hewett)
One thing that helps a bat hear well is its big ears. Large ears capture more sounds than small ears. Here is an activity you can do to demonstrate how this works. Cup your hands around your ears with your palm facing forward. Listen to the sounds around you. Do they seem louder? Take you hands away and notice the difference. In the picture above I was in a museum. I was pretending to be a bat. When I listened with the huge bat ears I could hear a pin drop on the other side of the room!HAPPY HALLOWEEN!
Note from a friend in Ireland about the origins of Halloween: As millions of children and adults participate in the fun of Halloween tonight, many will not be aware of its ancient Celtic roots in the Samhain festival. In Celtic Ireland about 2000 years ago, Samhain was the division of the year between the lighter half (summer) and the darker half (winter) http://www.newgrange.com/samhain.htm
