Nuance, the company that makes Dragon NaturallySpeaking for Windows, is in a pretty sweet position: It’s essentially a monopoly. One by one, its competitors in the speech-recognition business have either left the market (Philips ), gone out of business (Lernout & Hauspie) or turned over its product to Nuance (I.B.M. ). Even the sole Mac speech-recognition program, MacSpeech Dictate, can no longer be considered a kind of rival; Nuance bought it this year.

The NaturallySpeaking software points out matches when a word or phrase has been corrected.