Improving AI Conversations: Seeking Tips for More Natural Voices

Has anyone had any luck with getting the ai to sound more human - im testing a couple platforms out. I like the build capabilities and integrations with thoughtly but the conversations are not natural like some of the other platforms. Ive played with the settings in the conversations and tried a bunch of voices but none of them are sounding as natural as I like. Would we just have to api in a voice that we like? Open to suggestions here if people have it figured out