听力原文：L: Hi, Howard. What are you working on? H: Hi, Lisa. I've just finished a piece of background music. L: Background music? Oh, like the music they're playing here now. H: Yes. You hear it everywhere — in restaurants, airports, supermarkets... L: In banks too. I noticed it while at the bank today. H: You're not supposed to notice it. It's just in the background. It's supposed to put you in the right mood. L: I'm not sure I like that idea. H: Well, it seems to work. Companies pay millions of dollars every year for background music. It's supposed to give you a better feeling about yourself and the people around you. Factories use it a lot. It makes the workers happy, and they work better that way. In one factory, music increased production 4.5 percent. L: Now that I think about it, I can't remember when there wasn't background music in restaurants and stores. H: Yeah, I know that hamburger places play fast music. When they started playing faster music, they found that a customer spent only seventeen minutes eating. The time was twenty-two minutes before that. L: So they have more people coming in and out to buy hamburgers. H: Exactly. And that's good for business. You can see why music has become so popular. In Los Angeles, for instance, thirty different companies are selling background music services. L: I still think there's something about it that I don't quite like. H: I know what you mean, but lots of people would not agree with you. Howard is probably