We users are limited in what internal data we can see but Support, if sent a diagnostic can see much more.

Wait for the glitch and within a few minutes, sooner the better and not more than ten minutes, send the diagnostic. Note the number and contact Support. Do not post the number here.

A few ideas to try to identify the source:

 - You could also try listening just through the tv speakers and see if it happens?

 - Does it happen if you’re streaming music from Spotify, Amazon or the like or only when going from a tv source?  
- Does it happen if listening to a radio station on the tv?

Hello. I sent diagnostics and contacted support more than once. Now I will try to record a video and send it so that they can look at the problem. They asked for a video, not audio.

Hello everyone. I haven’t been able to record and send the video to Sonos by email yet, but I have conducted a few more tests to help resolve the issue:

1. I disabled the Wi-Fi signal repeater just in case, thinking it might be causing interference.

2. I turned off the Sub Mini and the two Era 100s, leaving only the Arc Ultra.

3. I swapped the power outlets.

4. I rearranged the power, internet, and HDMI cables connected to the Arc Ultra so that they wouldn’t touch each other — again, thinking this might reduce interference.

5. I disabled eARC.
   
   But once again, nothing helped.

And again I’ll ask:

 - Have you tried listening just through the tv speakers to see if it happens?
 - Does it happen if you’re streaming music from Spotify, Amazon or the like or only when going from a tv source?  
- Does it happen if listening to a radio station on the tv?

1. There’s no problem when using the TV speakers.

2. Tried streaming music from Spotify via AirPlay. There's a clicking sound.

Things can be strange at times. At one point I was working in a club lab on an air force base, repairing a tape deck for a friend. While testing the deck after the repair, I suddenly noticed a periodic, rather loud buzz — unlike any noise I had ever heard. After a while, out of the corner of my eye, I noticed the noise occurred as a radar antenna swung in my direction.

It’s possible that a high energy radio frequency source in your area is causing the problem. This could be due to direct radiation, as was likely in my case, or the energy could be transmitted through the power line or connecting cables. A well designed piece of equipment will be able to withstand a certain amount of this trash, but there are limits to this resistance.

Do you experience these noises if you are playing a music while there are no external connections to the ULTRA except the power cord? Are you using a high quality surge suppressor? Cheap “surge suppressing” power strips need not apply.

At this point we cannot rule out a physical defect in ARC that has reduced its effectiveness at blocking external interference. If ARC alone exhibits this interference, can you temporarily move it to a different location and power circuit?

Keep written notes because you may discover a correlation with other events in the area.

Here is the video with this strange clicking sound:

https://youtu.be/xmsSvEAfjl4?si=qrqdTAshRcFQwFdm

My Sonos Setup: LG 55” C1 OLED TV, Bit Stream input, Passthrough output, eARC, Sonos supplied HDMI cable. No speech enhancement enabled. Sonos Arc Ultra, 2 ERA 300 surround speakers, Sub Gen 3 and Sub 4.  

After trying many different options, I have found a permanent fix that has been working perfectly for me over the last five days and about 20 hours of TV usage.  Hopefully this easy fix works for others as well.  Here is my fix:

(1) Disconnect Sonos HDMI cable at Arc Ultra end and then firmly reconnect to Arc Ultra. 

(2) Disconnect Sonos HDMI cable at TV end (eARC HDMI Input) and then firmly reconnect to TV.

(3) Remove Arc Ultra power cable for 30 seconds and then reconnect and let Arc Ultra completely reboot.  You may also want to disconnect power cable from your TV, but I did not need to do that.  Use your TV and Arc Ultra and enjoy!

Good luck to everyone and I hope this easy fix works for others.  I’ll repost here if my clicking/popping sound reoccurs, but hopefully my problem is now fixed! 

Sonos support told me that the soundbar needs to be replaced. I asked two different specialists, so it's not that simple. I've disconnected and reconnected the HDMI and power cables many times. In my case, that didn’t help.
Do you have exactly the same clicking sound as in the video I posted above in the comments?

I experienced a similar but not identical clicking/popping sound from my soundbar, which generally occurred only after about two hours of continuous usage.  Also, when I paused my DVR, the clicking/popping noise would still occur. It is very likely that there are multiple root causes of this clicking/popping noise, some of which could be defective hardware.