阅读理解 Every year television stations receive hundreds of complaints 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 commercials sound so loud? The sensation of sound involves a variety of factors in addition to its peak 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 commercials is that much less variation in sound level occurs during a commercial. In regular programming the intensity of sound varies over a large range. However, sound levels in commercials tend to stay at or near peak levels. Other "tricks of the trade" are also used. Because low-frequency 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 (听觉的) 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 (辅音) are used, because people are more aware of consonants than vowel (元音) sounds. Finally, advertisers try to begin commercials with sounds that are highly different from those of the programming within which the commercial is buried. Because people become adapted to the type of sounds coming from programming, a dramatic change in sound quality draws viewer attention. For example, notice how many commercials begin with a cheerful song of some type. The attention-getting property of commercials can be seen by observing one-to two-year-old children who happen to be playing around a television set. They may totally ignore the programming. However, when a commercial comes on, their attention is immediately drawn to it because of its dramatic sound quality.

单选题 According to the passage, the maximum intensity of sound coming from commercials __________.

【正确答案】 A

【答案解析】辨认事实题。题目询问根据作者的观点，广告的最高音量和其他节目音量的关系。根据文章第1段和第2段：联邦法令严禁广告的声音高出普通节目的音量，而NBC高层人员也认为广告和普通节目的最高音量之间并不存在任何差别，而且广告的音量通常都一直保持在最高峰值或接近于最高峰值。因此，A项是正确的，与文中之意相符。

单选题 Commercials create the sensation of loudness because __________.

【正确答案】 B

【答案解析】辨认事实题。题目询问商业广告能保持较高音量的原因。根据文章第2段：商业广告声音较大的主要原因是商业广告的音量变化比较少。在普通节目中，音量的变化范围较广，但技术人员却使广告的音量一直保持在最高峰值或接近于最高峰值。由此可知，A项“电视台总是以最高的音量播出节目”，但这种音量既指普通节目的音量，也指广告节目的音量，因而这一信息与题意不符；B项与文中之意一致，因而正确；C项和D项均与文中所陈述之意明显相背。

单选题 Many commercials begin with a cheerful song of some kind because __________.

【正确答案】 C

【答案解析】辨认事实题。题目询问很多商业广告都以某种类型的悦耳的歌曲开场的理由。根据文章第3段：由于人们都已适应了某种节目所特定的声音，所以节目的音质如果突然发生戏剧性的变化将吸引观众的注意，而商业广告即是其中的一例。因此，A项与文中所陈述之意不符；B项与文中信息相背；C项与文中的观点一致，因此正确； D项的信息在文中并没有进行阐述。

单选题 One of the reasons why commercials are able to attract viewer attention is that __________.

【正确答案】 D

【答案解析】推断题。题目询问商业广告吸引观众注意力的原因。根据文章第3段：商业节目的制造者采用与其他节目截然不同的音响效果制作商业广告以吸引人们的注意力。而最后一段也指出广告独特的音质能立即吸引人们的注意。A项“人类声音能产生更好的听觉效果”和C项“用高频率的声音掩盖主要信息量的声音”，文中只提及这些是使音量一直保持在峰值上下的技巧，因而与题意不符；B项“公众喜欢音质能发生戏剧性变化的悦耳的歌曲”，显然与文中所给的信息相背；D项“商业广告的音量变化使观众感觉到发生了不寻常的事情，由此可推断出，它能吸引观众的注意力，因此与题意相符。