Yes, and it is annoying me to the extent that I wish I had picked a different company for my speakers.  Every time I launch my speakers I get a noisy commercial.  I get them in the middle of programming too.  Listening to the local public radio news station, the program suddenly stops, with silence for the next half minute or so, and then plays a noisy commercial.  Then it goes back to the program.  Meanwhile I miss the critical thing I was listening for.  
 

we pay enough for these speakers.  Sonos does not need to further monetize the system.  

To my knowledge, Sonos is not capable of inserting ads to a stream from Pandora. Pandora, however, is certainly capable of doing so. Have you checked with Pandora?

The Pandora stream just looks like data to Sonos, they wouldn’t know when a song starts or stops in order to give you an ad. 

Sonos would only be able to provide ads to their own radio service.

Sonos doesn't appear to care when a song starts or ends.  These ads just interrupt the programming wherever it happens to be, and when they return the programming resumes in the middle of whatever was playing.  It is especially maddening when it happens for example in the middle of music on public radio.

If you have the free Pandora account will get ads during playback. With the Pandora paid account ads are removed. Sonos does not insert ads into another company’s app or programming.

I listen to Minnesota Public Radio on Sonos speakers.  The people at MPR assured me that these ads are not theirs.  They have “sponsorship acknowledgements” which are somewhat like ads, but they do not interrupt programming in the way that these ads do.  We have compared specific examples.  They do not belong to MPR.  So who could be inserting them besides Sonos?

Pandora inserts ads.

I use TuneIn to listen to MPR on Sonos speakers.  Nothing to do with Pandora.  So the ads are coming from Sonos or from TuneIn.

How many times do you have to be told?  Sonos do not insert ads in another service’s streams!!!!

Is there a public statement from Sonos to that effect that I can hold them to?  I don't usually accept proof by dogmatic assertion, no matter how many times it is repeated.

You are the only one making this complaint. If this was something Sonos was doing people would be freaking out. 

Hi @Skauf

Welcome to the Sonos Community!

We do not insert ads into the streams of other music providers. Period.

I hope this helps. 

Thanks everyone for your thoughts and comments.  I have worked with Pandora extensively to understand why I hear ads when I have a premium subscription.  Sonos also said that they don’t insert ads.  What Sonos suggested was I delete Pandora from Sonos and re-install Pandora.  This may have worked.  Time will tell.