【文章內(nèi)容簡介】 ssage.Every year television stations receive hundreds of plaints about the loudness of advertisements. However, federal rules forbid the practice of making ads louder than the programming. In addition, television stations always operate at the highest sound level allowed for reasons of efficiency. According to one NBC executive, no difference exists in the peak sound level of ads and programming. Given this information why do mercials sound so loud?The sensation of sound involves a variety of factors in addition to its speak level. Advertisers are skilful at creating the impression of loudness through their expert use of such factors. One major contributor to the perceived loudness of mercials is that mush less variation in sound level occurs during a mercial. In regular programming the intensity of sound varies over a large range. However, sound levels in mercials tend to stay at or near peak levels.Other “tricks of the trade” are also used. Because lowfrequency sounds can mask higher frequency sounds, advertisers filter out any noises that may drown out the primary message. In addition, the human voice has more auditory (聽覺的) impact in the middle frequency ranges. Advertisers electronically vary voice sounds so that they stay within such a frequency band. Another approach is to write the script so that lots of consonants (輔音) are used, because people are more aware of consonants than vowel (元音) sounds. Finally, advertisers try to begin mercials with sounds that are highly different from those of the programming within which the mercial is buried. Because people bee adapted to the type of sounds ing from programming, a dramatic change in sound quality draws viewer a attention. For example, notice how many mercials begin with a cheerful song of some type.The attentiongetting property of mercials can be seen by observing oneto twoyearold children who happen to be playing around a television set. They may totally ignore the programming. However, when a mercial es on, their attention is immediately drawn to it because of its dramatic sound quality.31. According to the passage, the maximum intensity of sound ing from mercials ________.A) does not exceed that of programsB) is greater than that of programsC) varies over a large range than that of programsD) is less than that of programs32. Commercials create the sensation of loudness because ________.A) TV stations always operate at the highest sound levelsB) their sound levels are kept around peak levelsC) their sound levels are kept in the middle frequency rangesD) unlike regular programs their intensity of sound varies over a wide range33. Many mercials begin with a cheerful song of some kind because ________.A) pop songs attract viewer attentionB) it can increase their loudnessC) advertisers want to make them sound different from regular programsD) advertisers want to merge music with mercials34. One of the reasons why mercials are able to attract viewer attention is that ________.A) the human voices in mercials have more auditory impactB) people like cheerful songs that change dramatically in sound qualityC) highfrequency sounds are used to mask sounds that drown out the primary messageD) they possess sound qualities that make the viewer feel that something unusual is happening35. In the passage, the author is trying to tell us ________.A) how TV ads vary vocal sounds to attract attentionB) how the loudness of TV ads is overeC) how advertisers control the sound properties of TV adsD) how the attentiongetting properties of sounds are made use of in TV adsQuestions 36 to 40 are based on the following passage.In the United States, the need to protect plant and animal species has bee a highly controversial and sharply political issue since the passage of the Endangered Species Act in 1973. The act, designed to protect species’ living areas, and policies that preserve land and forests pete with economic interests. In the 1990’s, for example, the woodcutters in the Western United States were challenged legally in their attempt to cut trees for timber in the Cascade Mountains. The challenge was mounted to protect the endangered spotted owl (貓頭鷹), whose remaining population occupies these forests and requires the intact, ancient forest for survival. The problematic situation set the interests of environmentalists against those of corporations and of individuals who stood to lose jobs. After months of debate and legal battles, the fate of the woodcuttersand the owlswas still undecided in mid1992.Similar tensions exist between the developed and the developing nations. Many people in industrialized nations, for example, believe that developing nations in tropical regions should do more to protect their rain forests and other natural areas. But the developing countries may be impoverished (使窮困), with populations growing so rapidly that using the land is a means to temporarily avoid worsening poverty and starvation.Many of the changes to Earth that concern scientists have the potential to rob the planet of its biological richness. The destruction of Earth’s ozone layer (臭氧層), for example, could contribute to the general process of impoverishment by allowing ultraviolet rays to harm plants and animals. And global warming could wipe out species unable to quickly adapt to changing climates. Clearly, protecting will e only through coordinated international efforts to control human population, stabilize the position of the atmosphere, and preserve intact Earth’s plex web life.36. Why does the author say that the protection of endangered species is a highly controversial issue?A) Because people can’t agree as to what species to protect.B) Because it is difficult to find an effective way to protect such species.C) Because it affects the interests of certain groups of people.D) Because it is a major problem involving a series of legal procedures.37. According to the passa