Regardless of how I set the voice speed when using OpenAI Realtime API (4o or 4o-mini) the voice speed is identical. Is the Vapi Dashboard voice speed setting being properly translated to the realtime API's settings?

dont think openai realtime api has a paramater for speed adjustment so not surprise trying to adjust the speed paramater ui doesnt work. Maybe they forget they remove it from the ui when using realtime

Lennui, you cannot control the speed of Realtime model and these fields are left over there for backward comparability.