Rav Ovadia Yosef is lenient for recordings IF the man does not know what she looks like.
When it comes to speaking voice (Kiddushin 70), I learned that the Gemara is talking about going out of one’s way to hear a speaking voice – and that is Assur. Normally, we exchange information when we speak and that is Mutar. But talking for the sake of enjoying her voice becomes Kol Isha.