If you are testing with ChromeBooks, you may have a student who turns on the text-to-speech feature called ChromeVox within the secure browser. They can do this with the keyboard command Ctrl-alt-z. You may find that you can't turn it off. The way to turn it off is to hit ctrl-alt-z right after you hear the tone that indicates ChromeVox is on just after you launch the secure browser. You should hear a second 2-note tone that indicates it is now off.