Arc microphone constantly turns off and off by itself

Mine was doing the same, can you disable it though the Sonos app ? 

I just removed the voice assistance, it looks like you can't disable the Mic it from the app. Also, try tapping into the Mic button on the bar but it doesn't work. 
 

This is something Sonos should resolved. I will be opening a ticket soon. 

If you’re still encountering issues with the mic on the Arc, then it maybe best to submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support Staff via this LINK  and see what the Staff can perhaps suggest to resolve the matter.

Did you ever figure out this issue? I am experiencing the same thing. I have a Sonos Arc hooked up to an LG C1 TV via HDMI eARC, and am using Alexa as my voice assistant. When audio is coming from the TV, I hear the microphone turning itself on and off. It happens randomly, usually every few minutes though.

Have the same issue, Arc connected to an LG C3 OLED via eARC, tried Alexa, Google Assistant and Sonos Voice Control but the mic switches itself on and off constantly, have spoken to Sonos customer care, diagnostic report sent, the response was, this is very rare, never heard of it before and theyll replace the arc. Very frustrating.

Same issue here. Arc arrived yesterday. Today started randomly saying Mic on, Mic off.

I called support and he got me to do a diagnostics. Immediately said it showed a problem with the mic, and I had to wait on the phone while he spoke to someone else. Came back to me and confirmed it's a hardware issue with the arc and I would need another replacement as there is no fix possible. Also said that it's a known issue.

So at least we have confirmation from Sonos that there is a known hardware fault with the Arc, maybe a bad batch that is causing this issue.

He said he couldn't say how long a replacement would take, once they collected the faulty unit. This is really bad.

This is my second Arc in a week. First one arrived with a dent on the end cap part of the bar, which looked like a defect in manufacturing, rather than a transit dent, if that makes sense. Returned that unit for a refund.

The Sonos guy also said, hopefully third time lucky. Which isnt what I want when spending thousands on a premium products with Sonos.

Debating whether to return the arc, sub and ones and go elsewhere. Just down to Sonos and their CS response really. What am I supposed to do, keep paying out £900 a time to get faulty products, then sending them back for refunds hopefully within 30 days, in the hope that eventually I get a good one.

Opened a ticket went through the troubleshooting process. However, I noticed that after disconnecting the sub the issue with the mic was not longer happening, as soon as I added the sub back the issue started again. They decided to send me a replacement unit. 
 

So, for people having the issue can you try removing the sub (if you have it)? 

Just to update. Appears definitely a touch control hardware issue, as if I turn off touch controls in the app all is fine. If I enable touch controls it's also fine until I start playing music. I wonder if vibration is causing the switch to be activated. If I remove the assistant obviously the mic is disabled and all is fine.

Having the same issue. Just received my arc this week.

Will try contacting Sonos support to have it replaced, not looking forward to it based on some of your earlier experiences…

I got a Replacement unit from Sonos, 2 days to get it since I opened the ticket so, they did it pretty fast and the most important thing, I am not longer having the issue.