Late one evening last October I was visiting an old friend. Offering me food, he spoke the immortal words:
"I have fruit and juice and milk, if any of those appeal."
I wasn't paying attention, so I asked him to repeat it: "Say that again ...but backwards!", I added, because I like to seem whimsical and interesting.
After a short while I noticed he still hadn't replied. I looked over to find he'd opened a text editor and was busy figuring out how to pronounce the sentence phonetically reversed.
Of course, I immediately flipped open my laptop, exclaiming: "We can automate this!"
Aside: if you read xkcd, you might now mention this comic:
To which I would reply: shush, I'm having fun.
Hence followed a great evening: I hacked away in IPython Notebook, while Benjamin explained diphthongs and IPA and pronounciation.
Once our code worked, we tried speaking the result into Audacity, reversing it, and playing it back. We even sent the reverse-IPA to Nathan-from-the-internet—"could you record yourself speaking this?"—to make sure we weren't cheating somehow. (It made him very confused!)
The results were surprisingly understandable. Though there's definitely a certain trick to it making it sound accurate: you have put the emphasis in different places. You need to lower the pitch of the first word, not the last.
It's a weird effect, though! Foreign yet familiar. Apparently there's a scene from a horror movie (I don't like horror movies!) where they actually use this technique: the actors learnt their lines backwards, and then reversed the film.
The best part of all this was trying to get Benjamin to sing "Happy Birthday" backwards, tune and all...
I threw together this webapp as the result: speakbackwards.herokuapp.com
You can also see the IPython notebook we ended up with.