“It’s unbelievably better than it was five years ago,” said Dr. Michael A. Lee, a pediatrician in Norwood, Mass., who now routinely uses transcription software. “But it struggles with ‘she’ and ‘he,’ for some reason. When I say ‘she,’ it writes ‘he.’ The technology is sexist. It likes to write ‘he.’ ”

Meanwhile, translation software being tested by the Defense Advanced Research Projects Agency is fast enough to keep up with some simple conversations. With some troops in Iraq, English is translated to Arabic and Arabic to English. But there is still a long way to go. When a soldier asked a civilian, “What are you transporting in your truck?” the Arabic reply was that the truck was “carrying tomatoes.” But the English translation became “pregnant tomatoes.” The speech software understood “carrying,” but not the context.

Yet if far from perfect, speech recognition software is good enough to be useful in more ways all the time. Take call centers. Today, voice software enables many calls to be automated entirely. And more advanced systems can understand even a perplexed, rambling customer with a misbehaving product well enough to route the caller to someone trained in that product, saving time and frustration for the customer. They can detect anger in a caller’s voice and respond accordingly — usually by routing the call to a manager.

So the outlook is uncertain for many of the estimated four million workers in American call centers or the nation’s 100,000 medical transcriptionists, whose jobs were already threatened by outsourcing abroad. “Basic work that can be automated is in the bull’s-eye of both technology and globalization, and the rise of artificial intelligence just magnifies that reality,” said Erik Brynjolfsson, an economist at the Sloan School of Management at the Massachusetts Institute of Technology.

Still, Mr. Brynjolfsson says artificial intelligence will also spur innovation and create opportunities, both for individuals and entrepreneurial companies, just as the Internet has led to new businesses like Google and new forms of communication like blogs and social networking. Smart machines, experts predict, will someday tutor students, assist surgeons and safely drive cars.

The Digital Assistant

“Hi, are you looking for Eric?” asks the receptionist outside the office of Eric Horvitz at Microsoft.

This assistant is an avatar, a time manager for office workers. Behind the female face on the screen is an arsenal of computing technology including speech understanding, image recognition and machine learning. The digital assistant taps databases that include the boss’s calendar of meetings and appointments going back years, and his work patterns. Its software monitors his phone calls by length, person spoken to, time of day and day of the week. It also tracks his location and computer use by applications used — e-mail, writing documents, browsing the Web — for how long and time of day.