Thank you! I'm glad that you like the atmosphere of the game! ^^
There's no explicit hint at that part, but if you're stuck I can provide one here. (Spoiler)
After checking the radio again, a new item can be interacted with, so it won't be something that you've seen a message for before. (Look for something in a room that is suspicious or odd!) When you find that new item/message, there will be another message attached to something you have checked before to let you proceed.