Labyrinths were used in a lot of medium-level equipment with smaller-than ideal speaker enclosures, to try and make them give a better bass.
But it was a surprise to me seeing one in a vintage radio. Maybe I am not so old, after all.
Soviet-made Elektronika stereo record players of the ´80 vintage had plastic labyrinths inside the speaker enclosures. I saw one once and the labyrinth was not even fixed to the cabinet. Nice noises it made.
The one I saw was junk, so maybe it came from the factory correctly fixed to the enclosure, and later someone opened the enclosure, unscrewed the labyrinth and ended with some "extra" screws.