FOX Sports MLB Postseason Audio Aims To Make Officials’ Calls More Accurate

A1 Joe Carpenter hopes to bring some ‘baseball CSI’ to the ABS ump-cam system

FOX Sports will ride the 9%-viewer-bump of its ALDS broadcasts into the ALCS, which started yesterday, and then onto the World Series. But the audio won’t be resting on its laurels. A1 Joe Carpenter will still try to stretch a single into a homer by deploying a few new tricks, often a rarity for marquee postseason games. One trick could help the officials make close calls.

“We never stop trying, man; we take risks,” he says. “If anything, I tell all my guys I don’t ever want you going into this trying not to make mistakes. We just go for it. It’s the only way you get anywhere.”

FOX Sports’ Joe Carpenter: “Umpires have told me that they go by audio cues a lot, especially with catcher interference.”

For this year’s MLB Postseason, that will mean enhancing audio sources that have been taking on new importance in recent years. For instance, FOX Sports was among the pioneers putting microphones into bases, picking up the unique SFX of a stolen-base slide or the occasional conversation between teammates or even opponents.

“It’s great when you can get the third-base coach on a wire and hear him on the replay send the runner home,” he says. “That’s really exciting.”

Close-In Sound

The 2025 season marked the arrival of the Automated Ball-Strike (ABS) system: the umpire calls balls and strikes, but pitchers, catchers, and batters can challenge a call with high-resolution video, via Sony’s Hawk-Eye cameras, but no audio component. Carpenter plans to try to change that this postseason.

In a process he developed over several regular-season games in September, he will make a digital copy of certain key close-up audio sources — such as the base microphones or the parabolics along first and third baselines or behind home plate — on the Calrec Apollo aboard the NEP ND1 truck assigned to the ALCS games, placing them on a secondary layer of the desk. They can be called up on replays to isolate and highlight the unique sounds of a ball into a first baseman’s glove or the runner’s foot touching the bag.

“You would never hear any of that normally unless you had the [overall] gain structure cranked way up,” Carpenter explains. “I’m putting the second copy in a different layer of the console so you can crank those elements up after the fact, and you might be able to hear something that you wouldn’t normally hear, or determine something that just happened.”

And that’s where it could become the sonic complement to the ABS system, adding audio cues to the video to more precisely determine the true outcome of a very close play.

Audio Cues for the Ump?

“Umpires have told me that they go by audio cues a lot, especially with catcher interference,” he says, noting that the idea was sparked when a contentious regular-season game play at first was followed by a challenge on replay. “There was a bang-bang play at first, and, in the audio, you could definitively hear that the ball was caught in the glove before the stomp on the base. And I didn’t even have mics in the bases at the game!

“Now that we have mics in the bases,” Carpenter continues, “it’s definitive, like the snap of the glove. It’s a totally different sound. The way we [mike] our bases, you can definitely determine by the sound whether he beat the throw. If we can crank up those individual play sounds, you can tell if the ball or the foot gets to the bag first.”

Getting the audio precisely synchronized with the video is critical for making this pairing accurate. In this instance, that involves the use of a sync-audio beacon to verify synchronization of multiple devices or streams, using inaudible, ultrasonic signals. It’s a technique he has also tried out on golf shows, where the soundscape can go from near utter silence to a roar in seconds. Using cloned digital-signal paths offers a way to isolate critical SFX and recall them for replays instantaneously.

“Things that would have been drowned out by the crowd can now be brought up to the front and heard clearly,” he says, adding that, when paired with the ABS video, they make even the most difficult close calls that much more accurate.

Sound Everywhere

Other audio candy on postseason shows will include using outfield mics to pick up the unique sounds that each stadium’s foul poles make. Carpenter’s benchmark for that technique is Fenway Park’s “Pesky’s Pole”: the right-field foul pole, named after ’40s-era Boston Red Sox shortstop Johnny Pesky, makes a highly distinctive “thonk” when struck. Given foul poles’ criticality in determining a fair or foul ball, that kind of sonic cue could bolster officials’ decisions.

Those are the kinds of sounds that Carpenter and submixer Joel Groeblinghoff will be capturing at Toronto Blue Jays’ Rogers Centre Stadium. They’re crossing their fingers that the weather lets them keep the roof open and avoid the venue’s notorious standing waves, which have generated complaints about its acoustics since the ballpark opened.

He’ll also have a couple of Shure’s new DCA901 planar-array microphone systems to try out, possibly around home plate or along the lower first and third baselines.

But the idea of adding a sonic dimension to the increasingly surgical analysis of close plays in baseball is what hypes Carpenter the most this time.

“If I can get some sound clips together, we’ll be able to definitively prove some of these plays,” he says. “It’s evidence. It’s baseball CSI.”