[单项选择]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
A. pop songs attract viewer attention
B. it can increase their loudness
C. advertisers want to make them sound different from regular programs
D. advertisers want to merge music with commercials