Hello everybody
Some of you were right the problem comes from battery doctor. With the new update the app comes with a new function called "super optimise". So to remove the text to speech notification which bothers us so much, you have to start the battery doctor app, on the main screen you'll se the battery's level and just under that, a button "optimise". This one is classic we know it. But once you push it it appears a list of applications running background and, depending on the phones, a little button called "super optimise" is now here and is either on or off. When you turn it on for the first time this is how you enable the text to speech notification. So turn it off say OK and restart your phone.
I hope I helped you!
From France with love