 Why are there hidden microphones?
And in all of New York's millions, there had been only a hundred cases of intoxication during the previous year. He'd done that once and gone through a mountain of red tape to get another—everyone was required by law to carry a CPA ID card and show it upon request. When you try to get a job, they ask to see your ID before they even tell you if there's an opening or not. If your CPA ID says you're a DCT, you're SOL and they tell you there's no openings. jobs like all DCTs get. I've been a garbage man, street-cleaner, ditch-digger—" On the other side of the room, the jukebox came to life with a roar and a group of teen-agers scrambled to the dance floor. Feeling safe from hidden microphones because of the uproar, he leaned across the table and whispered in the girl's ear, "That's what I want to hire you for. A civilization weary of murder, robbery, kidnapping, counterfeiting, blackmail, rape, arson, and drunkenness had originated the CPA—Crime Prevention Association. There were no longer any prisons—CPA officials had declared loudly and emphatically that their job was to prevent crime, not punish it. They had made crime almost impossible, and during the previous year, only a few hundred men in the whole country had been convicted of criminal acts. Instead, he was sent to a hospital where all criminal tendencies were removed from his mind by psychologists, shock treatments, encephalographic devices, a form of prefrontal lobotomy and a dozen other methods. An expensive operation, but since there were few criminals—only ten in New York during the past year—any city could afford the CPA hospitals. The CPA system was, actually, cheaper than previous methods because it did away with the damage caused by countless crimes; did away with prisons and their guards, large police forces, squad cars and weapons. He was a hero to the millions of men and women who had suppressed impulses to kill someone, beat their mates, get drunk, or kick a dog. And therefore, an EX (a convicted criminal who received the treatment was commonly called an Ex because he was in the strictest sense of the word an Ex-criminal) ... The girl followed him across the room, around tables, through a door, down a hall, through a back door and into the alley.
 The hidden microphones are there to detect criminal activity, so the CPA can stop it before it starts.
 The hidden microphones are there because the girl is an FBI agent, looking to take down a mafia boss.  The hidden microphones are there to make sure the bartender keeps the drinks watered down.  The hidden microphones are there to detect criminal activity, so the CPA can stop it before it starts.  The hidden microphones are there as part of a drug sting.