http://www.nuance.com/naturallyspeaking/Here is the PC Magazine review:
Speech recognition has never been this good. Dragon Naturally Speaking 8 Professional, the latest incarnation of the popular speech-recognition engine from ScanSoft, is better at turning speech into text than any other commercial product on the market we've seen. And though it still makes its fair share of mistakes, correcting those mistakes is remarkably easy. If you've been disappointed with speech-recognition tools in the past, Dragon 8 could turn you into a believer.
We tested the rather pricey Professional edition ($795 direct), but the same engine underpins more consumer-friendly Standard ($99) and Preferred ($199) versions (see www.scansoft.com/naturallyspeaking for a rundown of the differences). During ad hoc testing at PC Magazine Labs, after roughly 20 minutes of training, Dragon was about 95 percent accurate, and this improved after more training and more practice. By comparison, IBM ViaVoice 10, the one-time Dragon archrival (now also sold and marketed by ScanSoft), was only about 70 percent accurate. Granted, Dragon can still be frustrating—especially in the beginning, when you're still getting used to it—but thanks to a slick tutorial wizard and a clever interface, it's far less painful than you might expect.
Training the app is easy—even fun. After about 5 minutes of reading something as enjoyable as Lewis Carroll's Alice's Adventures in Wonderland, the app will have a pretty good idea of your speech patterns; if you like, you can ask it to analyze your e-mail messages and Word documents, so it can get a good idea of your writing style as well. This typically takes somewhere between 5 minutes and half an hour.
After that, you'll need another 15 to 20 minutes to run the tutorial wizard, which explains each of the app's primary features and lets you practice along the way. You will find that practicing tasks with the wizard is a bit easier than using the product on your own, but don't let that bother you. After just a few more minutes of dictation, you should have things down.
More:
http://www.pcmag.com/article2/0,1759,1818453,00.asp