Ever wonder why overhearing a cellphone conversation is so annoying? American researchers think they have found the answer.

知道为什么听别人打手机如此心烦吗？美国研究人员称他们找到了答案。

Ever wonder why overhearing a cellphone conversation is so annoying? American researchers think they have found the answer.

Whether it is the office, on a train or in a car, only half of the conversation is overheard which draws more attention and concentration than when overhearing two people talking, according to scientists at Cornell University.

"We have less control to move away our attention from half a conversation (or halfalogue) than when listening to a dialogue," said Lauren Emberson, a co-author of the study that will be published in the journal Psychological Science.

"Since halfalogues really are more distracting（分心的） and you can't tune¹ them out, this could explain why people are irritated（恼怒的，生气的） ," she said in an interview.

Last year Americans spent 2.3 trillion minutes chatting on cellphones, according to the US wireless² trade association CTIA -- a ninefold（九倍的） increase since 2000.

Worldwide, there are about 4.6 billion cellphone subscribers（订阅者） , according to the International Telecommunications Union, a U.N. agency. The number is equal to about two-thirds of the world's population, leaving few corners of the globe where public spaces are free of mobile-tethered babblers（爱唠叨的人） .

China has the most cellphone users with 634 million, followed by India with 545 million and the United States with 270 million, figures from the U.S. Central Intelligence Agency (CIA) show.

Emberson said people try to make sense of snippets（片段） of conversation and predict what speakers will say next.

"When you hear half of a conversation, you get less information and you can't predict as well," she said. "It requires more attention."

The findings by Emberson and her co-author Michael Goldstein are based on research involving 41 college students who did concentration exercises, like tracking moving dots, while hearing one or both parties during a cellphone conversation.