The text reading works (have tested it reliably) by prompting you to say listen for the text to be played. It does not default read the text. So the worst that would happen is you have a phone say "Text message from _____" However if you have the phone on silent, she wont say anything (yes I assign gender specific pronouns to my phones). So silence the phone (which you should do anyways on a flight) and there will be no embarrassment.