In case you are using this block in your course, please beware that it will remove your ability to hide activities and resources. This feature also does not work for quizzes. You can remove the block easily from your course.
The text-to-speech feature is meant to allow moodle to read text to the user. When it works, it works well, however there are some drawback. We are presently reviewing the usefulness of this particular feature in moodle. If you have a better solution in mind, please let us know.