Questions11~15 are based on the following passageResearchers have shown that noise can adversely affect human in both physiological and psychological ways. Hearing losses in particular occupations such as shipbuilding and construction work are well -known . In fact, however, we all find hearing more difficult as we age . Young ears can distinguish a wide range of sounds from low to very high frequencies, while older ears lose the ability to distinguish high -pitched sounds. A comparison of people living in some industrialized and non-industrialized areas suggests that this hearing loss may not necessarily accompany old age . Furthermore, a closer inspection of other data reveals economic effects. For instance, an increased turnover in property ha s been observed in noisy areas near airports. Job performance can be adversely affected by loud noise, especially if accuracy and mental effort are involved. The use of outdoor areas for conversation is not possible for an estimated 5 to 10 million people who live or work in urban areas. When interference with television or speech or sleep is included, as many as 22 to 44 million people can be said to have lost part of the use of their homes and grounds because of noise. Thus noise pollution is a serious en vironmental concern. The indifferent attitude toward noise should be overcome considerable efforts should be made to alert people to the grave effects that may stem from an excessively noisy environment.We can learn from this passage that _______.