Here's how you can use the built-in text to speech feature on the iPad, iPhone or iPod Touch. 1. Open the Settings app. 2. Tap the General icon. 3. Scroll down and tap Accessibility. 4. Tap the Speak Selection option. 5. Toggle the Speak Selection option to On. 6. You can adjust the speaking rate by using the Speaking Rate slider under the Speak Selection toggle switch. 7. To hear text read to you, highlight the text and tap the Speak option that appears in the menu.
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Enabling text-to-speech on iOS devices | iLounge