EDIT: very unhappy with the update for Firefox 56. NO OPTION TO DOWNLOAD the audio for later listening. Will not update my other computers for Firefox 56 on 64-bit. Will no longer donate either, until this problem is fixed. (Their Chirpy equiv for Chrome is much worse.) I would gladly pay for a standalone for browsers and for Android.
The UK female voice is the best of any I've found anywhere, Ivona's 'Amy'. Only docked one star cuz the male voice is the same as used in Go Animate, not quite good enough; but ViJo's UK male voice in his Speechify is far better.
BUT THIS program itself is better. You paint the text, right-click or use the add-on bar or the icon in Customize (which you can move anywhere), to 'Speak It'. Some minutes pass while the thing renders, and when the voice starts, you;'ll notice you can DOWNLOAD the thing as mp3. Max running is about 90 minutes. You can convert a pdf to txt and it reads best that way. I did it with John Skylitzes (medieval historian of the Byz empire) and many scholarly docs. So I can lay back and listen, think. VALUABLE, this program.
I use it a lot, sample here: http://brainout.net/frankforum/viewtopic.php?f=44&t=706&p=3598#p3598
I hope ViJo will upgrade this, instead of using Speechify, as frankly this thingy is a gold mine. Or should be.
I contributed, and will keep on doing so, especially if the UK male voice in Speechify is ported to Text To Voice.
NOTHING like it on the internet, I've been searching for years.