The STTS Mobile Unity Plugin is the unity plugin that can use STT & TTS on Android and iOS.
The SDK enables unity developers to easily use 'Speech To Text(STT)' & 'Text To Speech(TTS)' on Android and iOS apps without having to write Java or Objective-C Code. The plugin provides a C# interface for STT & TTS that is used by C# scripts in your Unity project.
The developer guide provides a STTS API information
To find bugs, make feature requests, or to suggest other improvements, please use github's issue tracker