This feature is available in the Simplified Chinese, Traditional Chinese, English (U.S.), and Japanese language versions of Microsoft Office.
When speaking to others, you're usually understood whether you whisper or shout, or talk fast or slow. However, a computer understands speech best when spoken to in a more predictable way.
For example, the computer has a hard time understanding phrases such as, "This (pause) is (pause) another (pause) example (pause) sentence."
Because we don't usually need to think about how to speak, it can seem a little awkward at first to speak to a computer. However, with a little practice, speaking to a computer will become more natural.
If your work environment has a lot of noise or if the noise level varies during the day, try creating different speech recognition profiles for different times of day. If you work in several different environments, create different profiles for each environment.