The software fix for Sonos Arc and Beam (Gen 2) soundbars is rolling out now worldwide and you should install it to avoid loud popping sounds with Dolby Atmos MAT 2.0 sources.
Since late 2020, users have been complaining about the issue and Sonos finally acknowledged it in august 2023.
It took an additional three months to deliver a fix for the loud popping sounds. All owners of Sonos Arc and Beam (Gen 2) can install the system update via the Sonos mobile or desktop app (must also be fully updated).
Corrupted Dolby MAT audio segmentsAs mentioned earlier, the issue seemed to affect Sonos soundbars connected to Apple TV 4K and Xbox Series X, two of the only devices that transmit Dolby Atmos over HDMI as uncompressed PCM with metadata (Dolby MAT 2.0) instead of a compressed bitstream.
In a statement to The Verge, Sonos confirmed that the issue was related to Dolby MAT and shared some additional background information:
During our investigation we uncovered a rare bug that impacts how Sonos Arc and Beam (Gen 2) in certain home theater configurations process Dolby MAT, a streaming technology which is used to deliver Dolby Atmos audio over HDMI. Occasionally a Sonos product will receive a corrupted audio segment from an external source and needs to filter out unwanted audio data. The bug we identified was allowing our Dolby decoder to play audible errors on certain home theater setups rather than concealing them. The solution we’ve built and tested improves our Dolby decoder so it better filters out corrupt audio data that can manifest as a popping sound. We’ll continue to monitor customer feedback closely after the fix has been released and ship additional updates if necessary.