Puzzle #2511

There is a story of a talkative, highly-strung woman who hailed a taxicab in New York City. During the journey, the lady talked so much that the taxi driver got quite annoyed. Eventually he said, "I'm sorry, lady, but I can't hear a word you're saying. I'm deaf as a post and my hearing aid isn't working today." On hearing this the lady stopped talking, but after she had left the cab she realized the cabby had lied to her. How did she know?