Select the General tab then Accessibility > Speech > toggle Speak Screen on.This works with iOS devices running iOS 8 and newer: The highlighting is also really hit or miss, and trying to switch voices often doesn’t do anything. It doesn’t start reading much of the time, and the only way to get it to work again is to restart the device. Note: This Speak Screen feature is super buggy from my experience trying to use it on an iPad Air. One thing I noticed about the Speak Screen feature is you can even switch to other apps and continue to have the ebook read aloud in the background. The Alex voice is pretty good but it’s not as good as IVONA TTS voices. It’s a lot better than the default voice but the file size is a hefty 869 MB. There’s an enhanced voice for English (U.S.) called Alex. The defualt voice is the typical female robot TTS voice that’s not very good.
There’s a speaking rate dial to adjust the reading speed. There are a bunch of different voices that you can set for different languages and dialects. You can also set it to highlight content as it reads, or set it to add a speak button when you select text, and speak aloud auto-corrections. The new Speak Screen feature will read aloud content on the screen when activated. It builds off of the more limited VoiceOver feature that could previously be used for TTS to some degree but it’s cumbersome to use and doesn’t turn pages with ebooks. It’s a new accessibility feature introduced with iOS 8.
The text-top-speech feature is called Speak Screen.