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This is Scientific American’s 60-Second Science. I’m Cynthia Graber. This will just take a minute.

That’s a sound that inspires fear around the world: the dentists’ drill. And fear of that sound itself could play a part in keeping some people from getting their regularly-scheduled check-up. Now, a solution to this “sound effect” may be in sight, because researchers in London have developed technology to cancel out the drill’s unpleasant high-pitched whine¹.

Noise cancelling headphones usually do away with low pitches. So the scientists designed a variation that a dentist could keep on hand. The device fits between any MP3 player or mobile phone and the patient’s own headphones. The patients could still hear the dentist or listen to their own music. But the microphone and chip in the device sample the incoming sound and produce an inverted² wave that cancels out just the sound of the drill. As the drill’s frequency changes, the waveform quickly adapts to maintain the silence.

The researchers have built and tested a prototype. They hope that it could eventually finally provide a definitive³ answer to the question, “Is it safe?”

Thanks for the minute. For Scientific American’s 60-Second Science, I’m Cynthia Graber.

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收听单词发音

1 whine
v.哀号，号哭；n.哀鸣
参考例句：
You are getting paid to think,not to whine.支付给你工资是让你思考而不是哀怨的。 The bullet hit a rock and rocketed with a sharp whine.子弹打在一块岩石上，一声尖厉的呼啸，跳飞开去。

2 inverted
adj.反向的，倒转的v.使倒置，使反转( invert的过去式和过去分词 )
参考例句：
Only direct speech should go inside inverted commas. 只有直接引语应放在引号内。 Inverted flight is an acrobatic manoeuvre of the plane. 倒飞是飞机的一种特技动作。来自《简明英汉词典》

3 definitive
adj.确切的，权威性的；最后的，决定性的
参考例句：
This book is the definitive guide to world cuisine.这本书是世界美食的权威指南。 No one has come up with a definitive answer as to why this should be so.至于为什么该这样，还没有人给出明确的答复。