| 查看: 375 | 回复: 4 | ||
| 【奖励】 本帖被评价4次，作者ltl3s322增加金币 3 个 | ||
| 当前主题已经存档。 | ||
[资源]
[科学美国人-60秒科学]（09-04-22）一分钟新闻【已搜索无重复】
|
||
一分钟的科技新闻PDF+mp3，语速中上，有兴趣的可以下一下。五一发一小贴，估计都在放假 http://g.zhubajie.com/urllink.php?id=50177665ve27ync5qzok17i http://g.zhubajie.com/urllink.php?id=50177665ve27ync5qzok17i 下面是全文预览 April 22, 2009 Ear Cells Actively Amplify Sound A study in the journal Public Library of Science ONE reveals that the ear's hair cells act like tiny motors and respond to sound by swaying and driving electrical currents that cause positive feedbacks, which amplify sound. Karen Hopkin reports. Just when you thought you’d heard everything, scientists have found that the reason you can hear everything—including things that are very quiet—is because your ears have tiny tubelike motors that mechanically amplify sounds. You’ve probably heard that it’s the hair cells in your ears that allow you to hear. These cells sport tufts of spiky hairs that are like little molecular mohawks. When sound waves enter the ear these hairs vibrate, and that motion then gets translated into an electrical message that tells your brain that there’s something worth listening to. But the movement of those hairs is not passive, like tall grass swaying in the breeze. The electrical signals they produce feed back on the system, causing the hairs to tilt even more. It’s that so-called “flexo-electric effect” that basically boosts the audio signal and amplifies the sound, findings published in the April 22nd issue of the journal Public Library of Science ONE. The scientists behind the study also note that the length of the hairs in different species explains why animals like bats can detect such high frequency sounds. It doesn’t, however, explain why your kids can hear their cell phone vibrate two rooms away, yet they never seem to hear a word you say. —Karen Hopkin [ Last edited by ltl3s322 on 2009-5-1 at 20:38 ] |
回复此楼» 猜你喜欢
288求调剂 一志愿哈工大 材料与化工
已经有31人回复
-
一志愿北京科技大学085601材料工程英一数二初试总分335求调剂
已经有5人回复
-
085801 总分275 本科新能源 求调剂
已经有17人回复
-
324求调剂
已经有6人回复
-
学硕化学工程与技术，一志愿中国海洋大学320+求调剂
已经有7人回复
-
材料调剂
已经有5人回复
-
初试301，代码085701环境工程，本硕一致，四六级已过，有二区一作，共发表5篇论文
已经有6人回复
-
化学308分调剂
已经有15人回复
-
346求调剂
已经有3人回复
-
环境285分，过六级，求调剂
已经有6人回复
太快了，基本跟不上。 
5楼2009-05-13 18:07:13
简单回复
2009-05-02 11:32
回复
fanxs883楼
2009-05-03 15:44
回复
ttzzhang4楼
2009-05-11 20:20
回复
