Your phone has been able to talk to you for years, but it started out sounding like a computerized toaster with laryngitis. Google has improved its text to speech (TTS) voice over the years, and a new version is rolling out now. The change is fairly dramatic, with the new voice sounding much more natural and pleasant.

You can hear the old voice above on the right phone and the new one on the left. As far as we can tell, the new version is being delivered as a silent update in the background. No APK update is needed, and devices using the old voice appear to get updated to the new one after just a few minutes of testing.

There was an update to TTS recently that added new voice options, so it's possible the updated version was just flipped on. At any rate, you don't need to worry about installing anything. The new voice should appear soon if it hasn't already.