If a computer hasn't yet seized an opportunity to speak to you, get ready: Ma Bell is joining the legions determined to put computer conversation in your life.

In a "cost avoidance" move, C&P Telephone and other Bell companies around the country are switching to an operator-computer partnership for directory-assistance calls.

Audio Response Unit, as the computer service is called, will come on the line after the operator answers to take the request. The computer will recite the requested number in either synthesized or human voice patch--that is, either a voice created by a computer or a recorded human voice patched together by computer to give the requested information.

Bell projects that the innovation will save its seven regional telephone companies between five and nine seconds a call, which average 22 to 34 seconds, by reducing the time that customers and operators talk to each other. C&P says the calls now cost roughly a penny a second. Last year Bell operators answered nearly 4.7 billion directory-assistance calls.

"Anytime we can cut off that customer-operator interaction, especially with technology, for cost avoidance, we're going to," said C&P spokesman Alan Holder.

An IBM Audio Response Unit system was tested here between March 14 and May 6. Sixteen of the 300 Washington local operators were given a 45-minute training session to learn to operate the system, which disconnects the operator and brings on the computer to give the requested number.

"It's a hi-tech item, so operators don't really have to learn very much," said Martin J. Nilson, C&P's manager of operator services engineering. "It's almost rote."

Eventually all C&P operators will be trained to switch to the audio response. And according to Holder, "It allows us to delay adding additional operators."

C&P expects to put the computer on the line in downstate Virginia next month, in West Virginia in December and in the Washington metropolitan area by May.

Indiana Bell is the only system in the country that has switched completely to computer voice synthesis for directory assistance. When customers complained--and Bell says people in some areas of the country object to hearing synthetic speech--the sound chip was reprogrammed.

All regional Bell companies are in the planning or implementation stages of computer-controlled answering, and are scheduled to switch to it by 1985.

Bell's ambitious computer exercise might be the most pervasive example, but computers that talk are becoming common consumer fare.

In a recent "On the Road" CBS broadcast, a perplexed Charles Kuralt furrowed his brow while waiting in a supermarket checkout line as the cash register carefully recited the price of each item. He frowned at an alarm clock as it calmly told the time, and wrestled in frustration with a seat belt and door as his car politely reminded him to buckle up and close the door.

Computers almost always say, "Thank you."

A chatty Coke machine moved into Washington National Airport a couple of years ago. Now one also entertains at Union Station. They never forget to say thanks.

Minolta is introducing a 35-mm camera that in a feminine voice tells users whether the lighting and distance are correct for the shot. A local camera salesman, obviously piqued at what he considers bothersome chatter, complained, "Thank God it has a button that lets you shut that thing off."

Such is not the case in elevators that announce the floors or in stores where synthesized voices greet customers at the door.

Refrigerators now scold over-eaters. Casio offers a calculator/clock that not only tells the time and date but reminds you to walk the dog.

Jeanne Dietsch, a market analyst with Talmis in Chicago, laughs as she thinks of the possibilities of a wrist device that takes the wearer's pulse and soothingly cautions to "slow down, relax," if his pulse rate rises.

"Coke and so forth are doing this because it's a novelty and attracts attention from others in the market," she said. "I think you're going to see voices on all sorts of home appliances, talking coffee pots and so forth."

The biggest market is likely to be in home computers, particularly entertainment software for children and video games for both the home and arcade, she said.

A Bally "Star Wars" arcade game will replay sound from the movie.

"I would say voices on this kind of product has definitely got consumer appeal," Dietsch said. "It heightens the interaction, makes the character more real. If it's a good voice. If--it--does--not--sound--like--a--computer," she said, simulating a tinny, flat, staccato computer-synthesized voice.

Synthesized voices have a practical side. Reading machines have opened a new world to the blind. And machines that read the denominations of currency, as well as cash registers and other tools used to make a living have also made a considerable difference for the blind.

And some home security systems now have voices that can be telephone-activated so that owners of vacation homes can call their second home to check to see whether there has been a break-in.

But mostly, the computerized-products that talk are for fun. After all, who couldn't appreciate a computer that not only reminds you to change the oil in the car but thanks you for your trouble?