Bluefin Labs wants to know not how many people are watching a TV show, but what they’re saying about it. This week, the company, based in Cambridge, Massachusetts, launched its first product: Bluefin Signals, a tool for monitoring and analyzing audience reaction to TV shows, which it collects by simultaneously monitoring television and social media feeds.

Bluefin has spent the past three years building up the infrastructure, algorithms, and computing power needed to process the enormous quantities of data generated by social media sites including Twitter and Facebook. Currently, the platform processes more than three billion public comments each month.

For years, the success of a television show has been assessed using an estimate of the number of people watching a show provided by Nielsen, a company that gathers information using set-top boxes and diaries. But advertisers and producers increasingly also want to know who’s talking about a show, and what they’re saying. Bluefin Signals is designed to measure this side of an audience’s reaction using social media.

Bluefin faces competition from a growing field of startups, including Netbase and Viralheat, which also mine social networks for reactions to products and media. Other companies, such as GetGlue and Tunerfish, are building social networks around television content, and gathering data in the process. Bluefin executives say that the massive amount of data they collect and analyze sets their product apart. The most serious potential competition could ultimately come from Nielsen. The ratings giant has not yet announced a strategy for monitoring social media, but it is working on connecting its existing data to social media analysis.

Bluefin tracks which shows are scheduled to be shown on TV and also uses analyzes broadcast and cable television feeds from all over the United States frame by frame using fingerprinting to confirm that a particular show or advertisement is on screen. The company simultaneously crawls through social media feeds for mentions of television shows, and links those mentions to specific shows and commercials.

Many advertisers and television networks already monitor Twitter, Facebook, and other similar sites to learn how a show’s audience received it. But executives struggle to understand the implications—if a show gets 2,000 mentions on social networks, is that number was impressive or small compared to similar shows? “That’s one of the core problems we’re looking to solve for people doing this type of analysis,” says Tom Thai, vice president of business development at Bluefin. “Not only give them the numbers, but also the universe of context.”

Bluefin Signals provides two main ways of measuring an audience’s reaction. The first, called Response Level, tallies up the number of people commenting on a given show. It converts this to a 10-point scale so that people can assess that number in relation to other shows aired at other times. The second, Response Share, determines how much attention a show got while it was on the air.  Bluefin found that the NBA finals got about 45 percent of the response to television on social media on the night of May 24, compared with only 6.1 percent for American Idol. Bluefin Signals allows users to get a finer look at the data, by comparing shows within the same genre.

Thai says Bluefin’s product is most useful for assessing whether less popular shows are a good advertising buy. Many of these have similar audience numbers, so social media response could make certain shows stand out. He adds that eventually Bluefin can even reveal which shows get the best response to particular types of advertisements on social media.

A product like Bluefin’s could help fill in some key gaps for advertisers, says Jon Kleinberg, a professor of computer science at Cornell University who studies the social and information networks that underpin the Web and online media. “One thing that has made advertising work very powerfully in domains such as Internet search is that you know a lot about the person receiving the ad–what they’re doing at the moment, through their query or other activities on the site, and sometimes what they’ve done in the past as well,” Kleinberg says. “For other domains–broadcast media such as TV, for example–it’s traditionally been harder to form a picture of the ad’s recipients, at the moment they receive it.” Bluefin has the opportunity to “fill in the missing details” by measuring and reporting how audiences react to broadcast content in real time.

Bluefin is studying other fine-grained data, such as the success of commercials when paired with particular shows, and it plans to release additional products and features that make use of this sort of data.