Someone, please ask OpenAI to stop artificially dumbing down ChatGPT by adding "um" to the audio output. I get that it is supposed to make it more human-like or something, but every time I hear it do that, I cringe and feel sad for humanity.
You can sign up and use their Voice Lab for free or maybe a few bucks and experiment with the slider for Stability and the other setting.
In my opinion, turning Stability down just a little bit to demo extremely realistic speech is a no-brainer. They could have turned it up and made it ultra-smooth, but that makes no sense. Why make your robot demo less realistic deliberately?