During an otherwise routine panel at the Television Critics Association Winter press tour this week, NBC research president Alan Wurtzel dropped a bombshell: He knew—or at least had an idea—how many people were watching Netflix's original series. It was a sit-up-and-pay-attention moment. The head of research for a broadcast network was pulling back the curtain on viewership numbers that had long eluded TV reporters everywhere.

It's no secret that television networks have long wanted alternatives to the traditional Nielsen ratings. What Wurtzel revealed was that NBC had found one—Palo Alto-based Symphony Advanced Media, which had viewership numbers for Netflix and others. It drew the data from tech that was still "in beta," Wurtzel said, but it nonetheless showed Jessica Jones averaging 4.8 million viewers aged 18-49 while Master of None had 3.9 million adults in the same group.

Until now, no one has been able to approximate the audience for shows available exclusively on streaming services. Netflix’s numbers—other than subscriber figures it reports each quarter—are shrouded in secrecy, even for show creators. As it stands, Netflix will share data on its successes—noting that Beasts of No Nation was viewed 3 million times in its first two weeks of release, for example, or that The Ridiculous 6 is the most-watched film in Netflix history—but not much beyond that. Symphony—which touts Charlie Buchwalter, who spent 13 years at Nielsen, as its president and CEO—helps put an unofficial number on streaming viewership.

Collecting Data, Shazam-Style

Symphony launched its VideoPulse service in September, with NBC, Viacom, Warner Bros., and A&E as beta testers. Buchwalter says the system was designed to catch the "30-35 percent of viewership actually happening beyond" the live-plus-seven rating (L+7) that tracks a program's viewership during the seven days after it airs and is the standard used to determine advertising fees. VideoPulse then tracks the mobile streaming habits of users, who are paid $5-$13 based on how many devices they set up, to calculate viewership.

VideoPulse's sophisticated audio recognition technology lets the software run passively on a mobile device, identifying a television program through its microphone to log viewing habits. Instead of the set-top box Nielsen families use, Symphony created an app that tracks what users are watching in much the same way Shazam identifies a song playing at a party.

"We have a partner that has access to all 210 national channels in the US," says Buchwalter, "and every piece of content that comes over those channels has an audio fingerprint included in them, which has to do with a particular episode of a particular program on a particular network." When the service launched, it tracked all broadcast and cable programs. But throughout October and November, Symphony added tracking for high-profile, critically-acclaimed streaming service shows like Orange Is the New Black, Transparent, and Master of None.

For streaming shows, Symphony's app tracks the number of people who watch any episode of a particular series over a 35-day period, then averages that total to determine a per-episode rating. For example, Narcos averaged 3.2 million viewers aged 18-49. Amazon's Man in the High Castle, which has been identified as the highest-rated Amazon Prime original, averaged 2.1 million viewers.

Symphony is one of a few companies attempting to fill the perceived gaps in how Nielsen collects viewer data. And right now it’s going about it by forming a diversified user base from which larger demographic information can be extrapolated. "We have our own panel of around 15,000 mobile device users," says Buchwalter, who also notes that Symphony's app works with cell phone and Wi-Fi networks, as well as a GPS component to note where users are accessing media, whether it's "at home, in the car, or in the parking lot of a Target."

Looking Inside the Black Box of Streaming Viewership

Frustration with Netflix's secrecy about viewership numbers runs deep among TV executives, and Wurtzel, however obliquely, smashed the streaming service's black box viewership with his TCA presentation. To be fair, television executives have long complained that Nielsen ratings aren’t accurate and Symphony’s numbers are still in beta testing, but given how long everyone's been wondering many people are watching Netflix and Amazon original series, any data at all is eye-opening.

Netflix, for its part, remains unconcerned. A company spokeswoman declined to comment on the data Wurtzel mentioned, but said in an email that "generally speaking, these kinds of traditional ratings don't matter in a world where success isn't measured by specific time slot. They are especially irrelevant on a subscription service that doesn't sell ads. We measure success by subscriber numbers and hours people watch, and we do release those figures quarterly."

You could argue Netflix needn't worry about ratings because it doesn't have to worry about setting advertising pricing. But other subscription networks—HBO, Showtime, or Starz, to name a few—receive Nielsen ratings, which are a barometer of how their original content is received. Those numbers justify the cost of producing original programming. And considering Netflix has said it hopes to double the number of original series in the next year, it will be valuable to know whether or not the company is investing shrewdly in content, or just producing an endless stream.