In a book someone hears a woman voice and says:
As far as I know,
そう(な) is to say something seems based on visual information, and my grammars agree with this: things like
おいしそうなケーキ. If linked to something you heard,
そう is used to report what you said/heard, like
明日だそうだった, "I heard it's tomorrow".
Given the context, it seems to me that
そう is the first meaning, since the character isn't reporting something she heard.
そう the first meaning? If so, is that use wrong/unusual?