Scarlet says she was shocked to hear the voice in the 4o demo, and they had requested her consent (for the 2nd time) 2 days prior to the demo. If that demo voice was the same as the existing Sky voice, this wouldn’t be happening.

It was essentially the same, the new one is definitely more human like. I have been calling it Scarjo since then.

    Sam Pullara @sampullara
    If you have the ChatGPT app, set it to the Sky voice and talk to it. It is definitely a clone of ScarJo from Her.
    6:21 PM · Dec 13, 2023

https://x.com/sampullara/status/1735122897663094853

The voices were available for some time for the ChatGPT TTS model, but it seems that they reused them for the 4o audio output, which sounds significantly more human-like. I’ve heard the Sky voice before and never made the connection. I did think of Johansson though during the live demo, as the voice + enhanced expressiveness made it sound much like the movie Her.