Authority reversal
When the adults look to their child for entertainment in "I CAN SPEAK!" it is clear that they have neglected their role as authority figures. They have become passive agents, accepting the performance of their child. Then, they are astonished by their child. It's as if they are learning from the child what they were unable to accept in their own selves. The resulting inversion of authority is clear and ironic.
The human animal
The child in "I CAN SPEAK!" is obeying its instincts. When it starts to demonstrate instincts that frighten the parents, it is dramatic irony, because something about human nature is being revealed to them that was perfectly obvious to the child and (maybe) the reader. Humans are animals, and they are deeply amazing and sometimes frightening, but the parents forgot that because the entertainment they consume offers another version of human nature that they rehearsed so long they believe it.
The influence of mass media
The irony of mass media is that it is thoroughly effective. When they go to watch a film or movie, there are advertisements. When the grandfather tries to enroll his son in an artistic class, he accidentally leaves his child open for indoctrination by CBS. The "CommComm" world is literally shaped by the mass media, with what motivation? To make money for big businesses. Yet, to the people who exist in the clutches of the mainstream media, it is completely invisible. They tacitly accept whatever reality they are presented with.
Marketing as an evil
Although marketing is an essential aspect of a healthy competitive economy, it can go too far. For instance, the marketing that interrupts one's experience of art (like movies and television) are basically suggesting that art is about making money. This is sacrilege. Also, the way marketing shapes one's experience of self seems to be portrayed as ironically evil, especially in the nightmarish realm of "CommComm."
The sacredness of art
The irony that goes most skillfully concealed from the characters of the book is something the reader might be able to deduce. The author thinks that the sacredness of art has been defiled. He feels that art was supposed to be a holy thing, a religious endeavor into the truth of human nature and the human experience. Instead, art has been replaced by entertainment which serves to distract humans from the dilemma of their nature and death so that they spend money more wantonly. He feels this is literally evil, but he only argues that point through irony, showing the ad absurdum of advertising and marketing.
