I’m not seeing the issue, but have you tried rebooting the speakers post update and retuning the room? If so, and the problem persists with either Trueplay on/off, then maybe try unbonding/rebonding the surrounds and Trueplay tuning again.

As a final suggestion, adjust the ‘TV Level’ slider control over to the left in the Arc ‘room’ surround audio settings.

Still no joy, then after playing audio where you notice the issue, within 20 minutes of the issue occurring, submit a Sonos diagnostic report from the ‘Settings/Support’ area of the Sonos App. Make a note of the reference generated, and when practicable, contact/chat to Sonos Support Staff about the matter via this LINK and see what they can suggest to resolve the matter.

I’m not the only person with this issue after 14.18:

https://www.reddit.com/r/sonos/comments/y9qtav/surround_too_overpowering/

https://www.reddit.com/r/sonos/comments/y7qp01/1418_surrounds_are_noticeably_louder_for_nondolby/

The rear speakers are so loud that, when playing a game, the same dialog coming from the rear sounds twice as loud as the front speakers.

Did you try the suggestions (power-cycle & retune the room)? Also, does the ‘TV Level’ slider-control in the App not resolve the issue for you?

What Ken is saying is..go to system, then tv room, then “surround audio” under Sound listing, then  tv level and adjust it. 

I think you are joking with that to adjust rears? That is not the fix .. i have experienced the similar btw, like many out there (reddit example)

Why a joke? This depends on a number of factors, like whether or not, the room was rebooted and Trueplay tuned (post 14.18 update) as some users felt that helped.  Also there are ‘surround’ distance settings in the App that can be adjusted when Trueplay isn’t enabled.

The surround speakers should, when they are ideally placed, be behind and to the side of the listening position, but sometimes people place them elsewhere, close-by and to the side …and with/or without the balancing aspect of Trueplay, the TV Level slider control is one of many tools available in the Sonos App to assist with manual customisation. Why have such a tool to adjust the TV/surround level if it’s not used when needed? …and by some accounts of the few here, they say they need such an adjustment - so it is legitimate to try it and see if the manual customisation may work for them. Not every Sonos default setting suits every environment and we all hear things differently too.

Its a valid option to try in the App, at the very least.

It might also be helpful to know exactly what “type” of signal the game is sending to the Sonos system. Is it in fact Dolby Digital, or something else? You can open up the controller, go to Settings > System > About My System and look at the Audio In line for your Arc, to see what is being passed to it. 

And frankly, not all sources “balance” their output similarly. Some movies require me to adjust the surround levels in order to achieve the same “balance” as other movies. It boils down to the mix provided to the Sonos. 

Years ago it was folk complaining that their surrounds were too quiet and the same suggestion was mentioned back then, to "fiddle with the surround settings":

There is likely no way to please everyone with their various HT setups and different audio sources - However a ‘balance’ has likely been drawn to suit the majority …and for everyone else there are the customisation tools in the App.

However if there is a software ‘bug’ here with some types of audio codec, then the next best step is certainly to submit a Sonos diagnostic report from the ‘Settings/Support’ area of the Sonos App. Make a note of the reference generated, and when practicable, contact/chat to Sonos Support Staff about the matter via this LINK and see what they can suggest to resolve the matter.

The more data that Sonos can gather the more likely it informs them to resolve the issue and find the best output level for the HT setup, but I suspect with all the factors at play, there will still always be the need for the manual customisation tools in the Sonos App.

Same here. I have an Arc and two Ones as surrounds.  I don’t have a sub but for kicks i redid teueplay after 4.18. Now my surrounds are way too loud. DD and Atmos the same. I need to run them at -5 to sound right.  Eddie they were good with default setting of 0. Something definitely changed. 

I’ve noticed this as well. I’ve completely powered off all speakers for a few minutes, powered back on and retuned with Trueplay. The surround speakers are louder than the other speakers. I’m noticing what others have mentioned as well in regards to Trueplay resetting the Surround speaker distance to More than 10ft and my speakers are not that far. They should be the Under 2 ft option. What I want to know is if turning off Trueplay and changing the surround speaker distance, and turning Trueplay back on, will this affect the audio in any way besides noticing it being less overpowering, or would it be better to manually turn down the Surround volumes via TV and Music options?

I’ve also submitted Diagnostic: 677708686 after completing the complete reboot and retune.

I also had this issue but 2 nights ago I thought my sound was off again so went into settings and truplay had gone as in it was not setup.

I know it was there and switched on I had run it 4 times trying to get the sound right 

OK so I reran it and shock horror the surrounds were OK set on 0 rather than the -4 I was using also treble wasn't grating anymore, I had treble set at -6 now it's also on 0 

I have no idea what changed other than truplay wiping itself from my system but now it is much better 

I am still wary of it and won't auto update anymore but it's sounding better than 14.12 though not back to 14.10 glory days 

Wish I knew wtf happened so I can recreate it if any problems reoccur but I am happier than I was

Hope your system gets the same gremlin that fixed mine....

That is really strange. Could you tell me what the greyed out Surround speaker distance is set to for you? The audio has been great since the 14.18 update with Trueplay. Besides the surrounds being much louder than they should be and improper reading of distance.

@slongChez 

It's set at more than 10 feet

Got it, thanks for letting me know.

This is still not solved, is it? When playing video games the surrounds are way too loud making people standing behind me sound like they’re right on my back. I was stupid enough to re-tune my system with TruePlay after getting a rug because I thought it’d make a difference and here we are, worse sound. Prior to that I’d consider it as good as it gets. 

Why don’t you just adjust the ‘TV Level’ slider control in the HT room ‘surround audio’ settings - it’s the reason that (user) customisation control is there, to let you shift the audio level away from (or towards) the surrounds? 

Hey Ken, thanks for the answer and the suggestion. I understand why you would suggest that but it’s still annoying to update a system only for it to show different behaviour after the update although the content isn’t supposed to change surround functionality with true play. It feels like Sonos is shifting working out the details of true play to the end users and if I didn’t want a “plug and play” solution, I wouldn’t have bought Sonos.

I can only add that the tools in the Sonos App are there to provide a level of manual customisation by a user, for example my ‘old’ ears now prefer a little more treble than the ‘default’ setting, so I adjust some of my speakers treble-slider up a couple of notches, even after Trueplay tuning a room.

Some HT surround speakers can be placed a few feet away from the listener, or of course much further away and Trueplay tuning will do its level best to balance the speakers in their environment at a chosen spot and given the room acoustics and speaker distance you may go onto find the surround level it selects in the environment does not suit your own taste, so you would adjust the TV Level slider accordingly… I have several locations in my HT room, where I (or others) will choose to sit, so in my case I will make some manual adjustments to try to fit the setup to suit all those present in the room (it’s often a compromise), but that in some instances may mean shifting the audio away from the rear speakers. Regardless of ‘plug n play’ these tools are there to be used for our different room acoustics, listening positions & personal preference etc. Trueplay is v/good, but I doubt it will ever be a case of "one size fits all” - there are too many variables for that. 

So I would just use the TV Level slider control - and with some compromise you might get to the point where you can simply "set and forget" that setting.

My only wish here, is that I would personally like to see a TV Level slider control for both the left and right HT audio channels (a left/right HT balance control)… which I have put forward in the past to Sonos as a feature request.