There are strange sounds in many of the Stanley Cup playoff streams. They sound like modems in the background.
My investigation thus far:
https://community.frontrowcrew.com/t/strange-noises-in-nhl-stanley-cup-stream/3482
@rym I'm pretty certain this is audio watermarking. Five years ago, the Spanish soccer league La Liga's official app got busted for this. If the app detected the user was in a public place that didn't pay for a license to show the game, the app would turn the user's microphone on to listen for the game's broadcast audio. https://arstechnica.com/tech-policy/2019/06/spanish-soccer-leagues-app-caught-eavesdropping-on-users-in-anti-piracy-push/
These leagues probably send a different watermark to each broadcaster. The watermarks have to be loud enough to survive re-encoding, so it's noticeable.
