约五分之一12岁及12岁以上的美国人有至少一只耳朵听力受损

　　About one in five Americans age 12 and over suffers from hearing loss in at least one ear that is severe enough to interfere with daily communication, US researchers said Monday.

　　The estimate is the first to cover the entire United States instead of select populations according to location or age, said the study authors from Johns Hopkins University.

　　The findings, published in the November 14 issue of the Archives of Internal Medicine, a publication of the Journal of the American Medical Association, are higher than previous estimates of 21 to 29 million people with hearing loss.

　　The researchers took data from the National Health and Nutritional Examination Surveys (NHANES)， which has tracked Americans' health since 1971, and analyzed data from just over 7,000 hearing tests between 2001 and 2008.

　　Forty-eight million people, or 20.3 percent of people 12 and over in the United States, have hearing loss in at least one ear; while 30 million, or 12.7 percent of the population, has it in both ears, they found.

　　The researchers defined hearing loss as being unable to hear speech sounds of 25 decibels or less, which is the World Health Organization (WHO) definition for hearing loss.

　　Hearing loss becomes more frequent as people age, but the researchers found that it tended to happen less often in women than in men, and was also less frequent in blacks than whites.

　　Researchers are not sure why, but they suggested that the potential protective effects of the female hormone estrogen and the skin pigment melanin should be investigated as potential reasons.

　　According to the WHO, about 278 million people worldwide suffer from moderate to profound hearing impairment, or about four percent of the world population.

　　Hearing loss can be caused by a variety of factors, including infectious disease, loud noises, injury and simple aging. About half of all cases are preventable through prevention and early diagnosis, the WHO said.

　　据法新社11月15日报道，美国研究人员14日表示，大约五分之一12岁及12岁以上的美国人有至少一只耳朵听力受损，并且严重到足以干扰日常的交流沟通。

　　这次的估算还是第一次涵盖了全美而不是根据地区和年龄选择部分人口做调查，来自约翰霍普金斯大学的研究报告作者这样说道。

　　该研究成果发表在11月14日的《内科学文献》上，这是美国医学协会出版的一份杂志，结果显示出听力受损的人数超出了之前所预计的2100万到2900万之间。

　　美国国民健康与营养调查(NHANES)从1971年起开始追踪美国人的健康状况，研究人员从该调查中获取数据，并分析了2001年到2008年间超过7000份的听力检测数据。

　　研究人员发现，全美12岁及12岁以上人口总数的20.3%，也就是4800万人，至少有一只耳朵是听力受损的；而其中12.7%人口大约3000万人则是双耳都有问题。

　　研究人员所定义的听力受损是指听不见25分贝以及25分贝以下的谈话声音，这也是世界卫生组织(WHO)对听力受损的定义。

　　听力受损的情况随着年龄的增长更加频发，但是研究人员发现，这种状况往往在女性身上发生的几率比男性低，在黑人身上发生的几率比白人低。

　　研究人员还不能确定为何会出现这种情况，不过他们建议，应该把雌激素和皮肤黑色素的潜在保护作用作为可能的原因进行调查。

　　根据世界卫生组织(WHO)调查，全球大约有两亿七千八百万人患有中度到重度的听力障碍，相当于世界总人口数的4%。

　　听力受损是由多种原因引起的，包括传染性疾病、噪声、外伤或者仅仅是由于老化。世界卫生组织声称，大约有一半病例通过预防和早期诊断治疗得以阻止发病。