How Animals Hear(动物如何听到声音)
1. When we talk about ears, we usually mean the oddly wrinkled appendages on the sides of our heads.
2. We are aware that at the end of the central hole in this outer ear there is something called the middle ear, with an eardrum and a few little bones. Even deeper lies the inner ear, the organ with which we "hear".
3. Animals such as dogs and cats also have conspicuous outer ears, but few of us probably ever stopped to think whether there might be such a thing as a middle and inner ear beneath those pointed tips. Yet, we know very well that these animals hear.
4. Birds are even more mysterious, because here we do not even see an outer ear. The same is true to still a larger degree of such animals as frogs and fishes, although in the frog we can at least see an eardrum.
5. Again, at one time or another, you may have found that all such animals hear. Hunters know that birds are attracted by artificial calls, and fishermen emphasize that you should be as quiet as possible if you don't want to go home empty handed. And if you ever hunted frogs in your childhood, you know how softly you had to tread! Moreover, it seems absurd that birds should sing and frogs croak, if they could not even hear their own voices.
关键词: 职称，考试，辅导，资料 编辑时间: 2013-8-25