The explanation on the radio

The next day, the radio invited the woman in to explain what had happened. She sang the chorus and left. The studio microphone went with her, or maybe not. Some clues in this case come as riddles. If one stumps you, a hint will solve it. The clues no longer hand you everything on a plate.

Suspects

• Augusto, the radio director: He explained live on air that the woman wasn't from the radio. Then he explained that the microphone was.
• Belinda, the show's producer: She invited the woman to explain what happened. She's still waiting for the explanation.
• Crispim, the sound engineer: He cut the microphone halfway through the chorus. The country kept singing without it.
• Deolinda, the listener who always calls: She phones in to every show. That day she turned up in person, to make sure they heard her.