Power your device with the magic of Google’s text-to-speech and speech-to-text technology.   Google Speech-to-Text functionality 
  Speech Services provides speech-to-text functionality to Google and other third party apps to  convert what you say to text. For example, it can be used by:
• Google Maps when you use your voice to search places
• Recorder App to transcribe your recordings on device
• Phone App Call Screen feature to get a real-time transcription of your caller
• Accessibility apps like Voice Access for operating your device through voice
• Dictation or keyboard apps you might use to dictate text messages through voice
• Apps that contain a search by voice feature so that you can quickly search for your  favorite shows or songs
• Language learning apps that recognize what you say as you practice a new language
• …and many other applications in Play Store   
  To use Google Speech-to-Text functionality on your Android device, go to Settings >  Apps & notifications > Default apps > Assist App. Select Speech Services by Google  as your preferred voice input engine.    
  Google Text-to-Speech functionality 
  Speech Services powers applications to read the text on your screen aloud. For example, it can  be used by:
• Google Play Books to “Read Aloud” your favorite book
• Google Translate to speak translations aloud so you can hear the pronunciation of a word
• Talkback and accessibility applications for spoken feedback across your device
• …and many other applications in Play Store   
  To use Google Text-to-Speech functionality on your Android device, go to Settings >  Languages & Input > Text-to-Speech output. Select Speech Services by Google as your  preferred engine.   
  Note, on many Android devices, Speech Services by Google is already available, but you can  update to the latest version here.

Speech recognition and synthesis for your device.