The program Tomas is listening to is a montage of recordings; private conversations of Czechs recorded on secret bugging devices and brought back to Prague.
Tomas says that it all started with Jan Prochazka, a 40-year-old Czech novelist who in the 60s was outwardly criticizing public affairs. After the Russian invasion, the press tried to silence him with a smear campaign, but this just made the people like him more. Finally, the radio broadcast Prochazka's private, bugged conversations in which he made fun of many of his friends.
Tomas is disgusted and thinks that such a violation of privacy could only happen in Prague. But Tereza tells him that, when she was fourteen, she kept a secret diary. Her mother found it one day and read it aloud to all her friends during lunch.