You've probably heard that when proofing your book it's best to read it aloud. I think this is excellent advice. In the "old days," Robin and I would do the proofing of my books by taking turns reading aloud to one another. Why did we do it as a team? Well, because we often don't read what's on the page, we read what we "think" is on the page, which means we insert missing words or remove duplicated ones. Having both of us would usually catch the error because one person was following along and seeing where the other "auto-corrected."
When my wife got her first Kindle, it had text-to-speech built into the device. Then Robin started doing the proofing herself because the computerized voice doesn't skip or "auto add" words. It says EXACTLY what is on the page, and she can find those errors quickly and easily. Robin's Kindle is battered and beaten, and the headphone jacks no longer work. Plus, she can't plug her Kindle into the car radio and listen to the book while driving. Another solution was needed. Enter NaturalReader.
"NaturalReader is a Text to Speech software with natural sounding voices. This easy to use software can convert any written text such as MS Word, Webpage, PDF files, and Emails into spoken words. NaturalReader can also convert any written text into audio files such as MP3 or WAV for your CD player or iPod."Now Robin imports the book's doc file, converts them to .mp3 files, and puts them onto her iphone so she has them wherever she is and can even listen while driving.
Natural Reader has a few different pricing levels, including free.
We use the "Personal Edition" and it has worked very well for us. The great thing about Natural Reader is you can choose from a number of voices, which sound much more realistic than the standard "Steven Hawking" version used by most text-to-speech software. Plus the ability to turn them into mp3 means we can listen to them from virtually any device.
Given its low cost, I think it's well worth the investment. Give the free copy a try, and if it works out for you think of upgrading. I'm sure you'll find it pays for itself in the mistakes it finds.