You don''t have to look at the screen anymore.
Open the app for Preferences or add the home widget to enable/disable reading.
The preference dialog has a basic view to quickly change reading options. It also has an advanced view for more personalization.
With the home widget you can quickly switch through the most frequent reading options. Just tap on the widget and it cycles through silent setting, announcing names only and reading out the full text.
By default only the sender/caller name is enabled (for privacy reasons).
Note: this app is distributed as is, I don''t have the time anymore to add new features. It''s pretty stable though, so it does what you need.