missing a voice you're not sure you know — "often spoke on the show as…"
often spoke on the show as if she were talking exclusively to one person or character who was very important to her
Context
The era's characteristic intimacy: Mario grieves a radio voice on hiatus as if for a person, and the grief is real even though he's never met her and isn't sure he knows her. What makes the voice feel like a private address is that Madame Psychosis broadcasts as though speaking to one crucial listener — so each solitary listener takes the one-way transmission personally, a connection felt intensely and running in only one direction. The lonely reach for the voice that seems to be reaching only for you.