Nielsen will officially be introducing out-of-home ratings next April. Using its sample of 75,000 portable people meters across 44 markets, Nielsen will start to give clients a more scientific look at who’s leaving their humble abodes to watch NFL games and “Empire.”

These out-of-home numbers won’t be integrated into the ratings used in ad deals (the “currency”) until “a later stage,” according to Nielsen. The data that will be released to clients starting in April will include numbers stretching back to January, with more batches including data from September through December of this year to follow.

Out-of-home viewing wasn’t being entirely discounted by the TV industry this whole time, though. Particularly when it came to sports, advertisers all knew a certain percentage of their viewership was coming from bar, airports, and other places without Nielsen meters, and wasn’t showing up in the official Nielsen tally; the percentage was being guessed at and baked into the pricing of the spots bought.

But one of the big beefs with counting out-of-home viewing is that environments like bars and airports can be hellish audioscapes, and for advertisers, if someone can’t hear an ad, it doesn’t count. With the portable people meters, only ads that the meter can “hear” will be counted.

And now that ESPN has actually found a major agency to tack the out-of-home numbers onto guarantees (though likely at a discount), there’s a real impetus for Nielsen to push this product into the marketplace at large.

“This new service gives us the ability to capture out-of-home viewing precisely as it happens, and helps us double down on the power and delivery of live sports, while transacting on new, valuable audience segments for advertisers,” said Artie Bulgrin, ESPN’s senior vice president of global research and analytics.

ESPN had resurrected talk of including out-of-home in guarantees at its upfront event in May. It was seeing lifts of 9% for certain college football games, and up to 16% for other programming. In a world of skyrocketing sports rights fees and shrinking subscriber numbers (ESPN has seen its subscriber base erode to under 90 million homes), the ability to show where those eyeballs are going — and what they’re watching — is important.

Not that these out-of-home numbers will be some sort of panacea. They’re unlikely to truly lift ratings for primetime NFL games out of their current funk, and by the time the data has been rolled out in April, the season will have long been over. But it is one more piece of Nielsen’s “Total Audience Measurement,” an attempt to create a full picture of viewers on all devices (and their ad-watching behavior) that will be available for use in transactions on March 1.

Turner recognizes that today’s audience measurement requires constant innovation to capture the full scope of audience behavior,” said Howard Shimmel, Turner’s chief research officer. “For brands like CNN and Turner Sports with huge and valuable out-of-home audiences, we need to be able to measure consumption regardless of the platform, screen or location.”