Brian Steinberg Senior TV EditorAdvertisers still want TV to deliver big audiences, but they are also increasingly demanding new abilities to find smaller ones.NBCUniversal on Tuesday used an annual technology conference to keep demonstrating new technologies that help Madison Avenue track all the discrete consumer niches that may be found within the broader audiences watching TV programs. One new effort, an artificial-intelligence engine known as a “harmonizer,” aims to help marketers “make sure we are finding consumers at the right moment based on specific behavior,” says Josh Feldman, global chief marketing officer of NBCUniversal’s ad-sales unit.Using NBCU’s data about how viewers watch programs on the company’s streaming site Peacock, he says, advertisers might be able to assign an ad specifically created to “welcome” a new subscriber to the service, or feed particular commercials to customers who often watch programming late at night — even if they are tuning in at other times of the day.