Speaking backwards involves a lot of practice and repetition. You need a few things to start so we recommend a paper and pen, a mirror and some sort of recording device that has the ability to play forwards and backwards.
It is important to look at the words and how they are broken down into sounds. It is important to note that in speech, we don't say every letter but the combined sounds. This is essential to mastering the sounds to break down words so they can be replayed and make sense. Just like learning a normal language, it's is repetition and practice. Once you master this "alien language", you can amaze your friends and will be the bit at social functions or parties.
Of course, there are apps you can download or computer programs you can install that will play the words backwards but it is not the same as using your brain to form the sounds required. Writing backwards is easier than talking backwards. Some famous people who wrote backwards or mirror writing to avoid persecution included Leonardo da Vinci. Also many script writers or crime writings have written alien languages or hidden clues or a code for readers to figure out in their plots.
If you are trying to master the sounds of talking backwards, make sure you do it when not a lot of people are around as some of the noises made could sound offensive or inappropriate! Besides people may look at you funny if you were speaking a funny "alien" language. Another famous alien that spoke wisely but in a weird way was the famous little green Jedi, Yoda. Everyone delights in repeating his little quips.
If you are interested in learning more about "alien" languages or learning a backwards version of English, make sure you click the below link at 'About Entertainment' and enjoy!