美國人1/5聽力受損 會干擾日常交流

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.據法新社11月15日報道，美國研究人員14日表示，大約五分之一12歲及12歲以上的美國人有至少一隻耳朵聽力受損，並且嚴重到足以干擾日常的交流溝通。

這次的估算還是第一次涵蓋了全美而不是根據地區和年齡選擇部分人口做調查，來自約翰霍普金斯大學的研究報告作者這樣說道。

該研究成果發表在11月14日的《內科學文獻》上，這是美國醫學協會出版的一份雜誌，結果顯示出聽力受損的人數超出了之前所預計的2100萬到2900萬之間。

美國國民健康與營養調查(NHANES)從1971年起開始追蹤美國人的健康狀況，研究人員從該調查中獲取數據，並分析了2001年到2008年間超過7000份的聽力檢測數據。

研究人員發現，全美12歲及12歲以上人口總數的20.3%，也就是4800萬人，至少有一隻耳朵是聽力受損的；而其中12.7%人口大約3000萬人則是雙耳都有問題。

研究人員所定義的聽力受損是指聽不見25分貝以及25分貝以下的談話聲音，這也是世界衛生組織(WHO)對聽力受損的定義。

聽力受損的情況隨着年齡的增長更加頻發，但是研究人員發現，這種狀況往往在女性身上發生的機率比男性低，在黑人身上發生的機率比白人低。

研究人員還不能確定爲何會出現這種情況，不過他們建議，應該把雌激素和皮膚黑色素的潛在保護作用作爲可能的原因進行調查。

根據世界衛生組織(WHO)調查，全球大約有兩億七千八百萬人患有中度到重度的聽力障礙，相當於世界總人口數的4%。

聽力受損是由多種原因引起的，包括傳染性疾病、噪聲、外傷或者僅僅是由於老化。世界衛生組織聲稱，大約有一半病例通過預防和早期診斷治療得以阻止發病。