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 and you can't tune them out, this could explain why people are irritated," she said in an interview。

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

　　Worldwide, there are about 4.6 billion cellphone subscribers, 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。

　　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 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。

　　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。

　　康奈尔大学的科研人员称，无论在办公室、火车还是汽车上，只听到一半的手机谈话比听两个人的完整对话更耗费注意力和精力。

　　将在《心理科学》杂志上发表的研究报告的撰写者之一劳伦•艾伯森说：“相对于倾听一段完整的谈话，只听到一半的谈话让我们更难以转移注意力。”

　　她在采访中说：“‘一半的谈话’的确更易让人分神，而你又不能不听，这可以解释为什么听别人打手机会心烦。”

　　据美国无线贸易组织电信工业协会的数据显示，去年美国人打手机聊天的时间达2.3万亿分钟，比2000年增加了九倍。

　　据联合国国际电信同盟的数据显示，目前全世界约有46亿手机用户，占全球总人口的三分之二，手机用户几乎遍布世界的每个角落。

　　美国中央情报局的数据显示，中国的手机用户最多，达6.34亿，其次是印度，为5.45亿，美国位居第三，为2.7亿。

　　艾伯森说，在听别人打手机时，人们总想弄清说话人所说的只言片语的意思，并预测说话人接下来会说什么。

　　她说：“当你只听到一半的谈话时，你得到的信息较少，也不好去预测，所以需要更多的注意力。”

　　艾伯森和研究报告的共同撰写人迈克尔•戈德斯坦让41名大学生做了一项注意力练习，比如让他们在听一个人或两人在进行手机谈话时追踪移动的小圆点。他们的研究发现基于这项测试。