Room with glass windows as a walls.

If acoustic treatments are not possible. Then the route to go would be to use very warm components and speakers, less resolving lowering treble.

       The densest/heaviest/least acoutically transparent ripple-fold curtains* you can find, with the deepest ripples available.

        Prevent sound waves from reaching the glass and being reflected back into the room, as much as possible.

         *https://vitaliainc.com/what-you-need-to-know-about-ripple-fold-drapery/

                                                          and:

                    https://www.acoustic-curtains.com/curtains/acoustic-curtains/

                                                  Happy listening!

@rodman99999 is correct. Also, the use of thick area rugs and overstuffed furniture helps. Anything to absorb some of the echo that will be generated in that room.

I would think curtains to be the obvious partial solution.

 Headphones.

A few of these placed strategically my help. Other options also https://www.ikea.com/us/en/p/mittzon-frame-w-cstrs-acoustic-screen-gunnared-beige-white-s39514683/

Darko also had a pice on the IKEA product. https://darko.audio/2024/06/cheap-easy-room-treatment-with-ikeas-new-mittzon-range/

Over-treat what you can treat, and use tone controls. Respect how others listen. Many just want to hear the notes and tempo and the concept of building a 3D acoustical space is unimportant to them.

Control directivity.  Small 2-ways with horns like the Hsu satellite speakers can be ideal.

Just play on low volume

Has your daughter complained or even noticed any problems?  Why try to solve problems that don't exist?

This video from Acoustics Insider says that windows are relatively similar to drywall. Approach reflection points in a similar manner.

I haven’t found heavy, lined drapes make any difference although I haven’t tried the "ripple fold" variety.

Synergistic Research sell small "room tuning" devices called HFT’s that could perhaps be utilized. Pretty sure you can return them if bought from The Cable Company. Might be worth exploring.

@rodman99999 

+1

@onhwy61  Yes, she definitely noticed the problem, but as I see she is too overwhelmed with adapting to the new place, organizing everything there, so sound system is not priority yet. Also she is trying to be more independent and I think she will not complain anyway but probably she will just limit her listening instead. 

@rodman99999  Thanks Rodman, ripple-fold curtains is way to go. We’ll definitely consider that.

@ozzy62  Yes, Ozzy a big fluffy area rugs is definitely under construction. I already told her to look this way and she took the advice. Tnx. 

I would use paravans. Obviously one doesn't live in a glass box to cover it up, there must be views. Having played with deflectors by my speakers, paravans may have the exact affect and a nice Japanese is decorative too 

@surfmuz -

         With the correct acoustic curtains; the window reflections will be almost infinitely tuneable, with the pull of a cord.

                                         Can't hurt!

                                     Happy listening!

Listen nearfield.

Absorbers, absorbers, nothing but absorbing material in a glass room like that. Diffusers definitely not needed. Tubes and all copper cables also a good approach. Try to aim the speakers with first reflection points at solid walls. She sounds like a cool daughter.

Lots of glass windows? Is this a loft apartment with high reflective ceilings, hard uncovered or untreated floors. Very little furniture to dampen reflective sound waves?

Large open dimensional space? Starting with the windows is most likely the real killer in the picture, but also, just a beginning. To properly condition a space like this (assuming I'm correct) is a nightmare for an amateur. Hiring an acoustical specialist would most likely present a cost beyond the value of the system.

Sounds like you'll be chasing this problem around without much true acoustical satisfaction, For a long time.

If your daughter is a "serious listener" as opposed to just a casual listener, the sublime answer may be a good quality pair of headphones. Less hassle and less expense in the long run.

Admittedly however, the drapery treatment, as several have mentioned, plus a lot of cushiony furniture will definitely help the situation, without going crazy. Listening at lower volumes will help as well. But don't rule out component placement. Especially the location and positioning of the primary satellite speakers. I'm certain that some experimentation is this area will yield a number of different results.

I don't know what caliber of equipment she has. If it's just "mid-fi" as I call it, trying to treat the listening space is probably not worth it. 

If sound really matters to her, the other consideration might be to move at an opportune time. Then choose you apartment listening space carefully as much as other living space considerations.

@axpert  No, it’s not a loft apartment with a huge open space, and no reflective ceiling, floors are laminate. It’s one bedroom apartment with office room and living room divided by structural wall, but that wall is actually not a full wall and not connected with a glass window wall on the side, the space between them is approximately one feet. The system and speakers are facing this structural wall and the other window glass wall is behind the speakers. 

I suggest heavy curtains, a dense rug and DSP! I place acoustic panels along my windowed wall while listening. Gotta work with you have!

Many years ago the acoustics company I worked for was the 4th company to try to put in a sound system in the newly built Crystal Cathedral in So. California. Clearly it was an impossible job and our Lead engineer said they would have to put in satellite speakers behind every seat. Well that was to expensive but ultimately concessions had to be made to the look of the interior to get the RT60 to something  close to intelligible. Sometimes you just can’t win?

Obviously, the easiest audiophile solution would be to move and build a new home with a dedicated listening room and its own electrical source. Other than that, I can be of no assistance. Or... just enjoy life and the accompanying soundtrack to its fullest extent.

sounds like a lot of people's wasted time on advising the OP, when OP did not describe the floorplan in the first place - which would have been key to avoiding all these rabbit holes for us.

In extremely reflective envrons there seems to be only two solutions, both mentioned here.   1) dampen the hell out of it (heavy curtains like theater curtains- very expensive) , 2) distributed low level nearfield playback that doesnt energize the room enough to hit the reflective surfaces (Donavabdears post). Also complicated and expensive.  Narrow dispersion can help but it has its own problems of being beamy with a very small sweetspot that is hard to find in both planes (vertical and horizontal). But if you can find it, that can at least provide some measure of enjoyment.  For most, rooms like this are usually a long process of experimentation and money that usually ends as "cannot be fixed".  The Crystal Cathedral story is a great example:  still sucks after hundreds of thousands invested.   Glass heavy rooms are the one case where being an audiophile and fussing over sound quality doesnt work out well. @winoguy17 is right!

DSP.

Your query reminded me of this video in which the speakers sound pretty damn good in what appears to be an acoustically awful room.

There was also another video (same speakers/room) with different music, but I could not find it.

Was the sound doctored, or did they actually achieve this sound @ the listening position?

https://www.youtube.com/watch?v=WGtXhRDpLJU

DeKay 

I also deal with (in my lessor set up) lot's of glass and a spouse who likes the shades open. Shades, curtains, rugs all help. And there's also DSP.

Flipping may help. Putting speakers near windows with some small treatment panels could help..

St Jude?

Glass walls are rough.  If there's ANY possible way for her to hang acoustic clouds on the ceiling, that would be my suggestion.  You can make them yourself for super cheap or order them from a company like GiK Acoustics.  Minimal issue, just need to cover the holes and paint that part of the ceiling when she moves if she's renting.  Also not sure if every single wall in the room is glass, but if you can get paneling up on any of the NON glass windows, that would be ideal. 

And one more suggestion would be, if she can stomach it, use adhesive or command strips and hang at least a decent size section at first reflection 4-6" thick of the thicker stuff on the window where her first reflection point is.  Or again, buy some panels from GiK for first reflections.  With clouds, and first reflections covered, and if her rear wall is not glass, putting some diffusion on there, would help massively!  Best of luck to you and to her!

@rodman99999 ‘infinitely tuneable’ - +1 : )

I respect that the OP has good intentions as are all the responders, but the situation getting absurd in that a bunch of old men, at least demographically speaking, are advising a young woman on how to decorate her apartment.  Are we next going to give her makeup and clothing advice?

Sometimes it best to let your children figure it out themselves.

I apologize in advance for sounding like an old, cranky guy.

lonemountain

In extremely reflective envrons there seems to be only two solutions, both mentioned here. 1) dampen the hell out of it (heavy curtains like theater curtains- very expensive) , 2) distributed low level nearfield playback

There is an another option. Get Wavetouch audio speakers. Unlike other speakers (more 1st reflection points on walls, floor, and ceiling), walls and a floor influence much less to WT speakers’ sounds.

One must find used WT speakers. I have no time for WT speakers for a long time. Alex/WTA

@onhwy61 very true, it's implied in his post that she doesn't care about these issues

I agree with the earlier DSP suggestion. Grab a Leagcy Wavelet and let it help tame things.

@onhwy61 you right, youngsters needs their freedom, totally agreed with you, I’m actually proud of my kids being free and independent at their young age, however when you know your child and when you see that she is interesting in something you interesting too, you want her to keep running that good game and you want to be helpful that’s all. 

@grislybutter why you misinterpret my post!? Did it tell that she doesn’t care about the issue!?

@surfmuz

Does your daughter use ROON or JRiver for audio streaming?

If so, call Digital Room Calibration Services, Convolver, Headphone Filtersets (accuratesound.ca)

Mitch Barnett will setup DSP for your daughter’s audio space to make her system work.

You will not need any physical acoustic panels using the convolution files that Mitch will create. This guy is a genius Audio Engineer and written an impressive book on DSP (see Amazon.com).

The cost is $750, and he will create the DSP files remotely (with your daughters input). Your daughter first acoustically measures the room using a decent mic ($100), free software, and a laptop.

Doing DSP this way is way more effective than using any DSP features on any low computing audio gear.

Resources – Audio Digital Signal Processing - Accurate Sound

@ yyzsantabarbara No Roon or JRiver. She has access to my Qobuz Studio Family tire and she stream it via Teac NT-505.

@surfmuz Last I looked a JRiver license was about $75 while ROON is a lot more. However, if you think of those 2 as a piece of audio gear, it is not that much. I use a very cheap ($500) DELL PC to run ROON. The same can be done for JRiver and then connect to QoBuz. My cheap $500 computer is in a different room from my audio gear (a different floor too).

Not sure about the cost of ROON these days but I bought a lifetime subscription 10 years ago for $450. The best audio purchase I ever made.

What I suggested with the DSP done using convolution filters will 100% solve your daughters' audio room.

She actually understands all my explanations about acoustic issues at new place, but she doesn’t take it seriously.

You can avoid being interpreted in ways you don’t like easily. Don’t be vague. Describe the situation unambiguously. 

Use a pair of Magneplanars or similar dipoles which have less interaction with the sidewalls the room. That will at least mitigate reflection problems.

I have used the large Marigo dots for windows successfully for years. If she can accept 2 - 3 inch white dots placed towards the corners of the windows in the listening area, this may be the solution. 

@grislybutter do you think it would be helpful to describe it unambiguously when the situation is ambitious!?

I don’t mean to aggravate you @surfmuz but you can see people are trying to help but they are lacking basic info to understand what you need. Such as what matters to your daughter, the floorplan you later described, her interior design preferences, budget, etc. For instance, in my reading, you are trying to help her but she is...

somewhere between indifferent to not seeing this as a priority?

How do you help someone who is happy/fine with the status quo? I have helped (tried to help) my kids, friends and neighbors and ran into the same issue, people need to want to be helped for it to work.

Use a pair of Magneplanars or similar dipoles which have less interaction with the sidewalls the room. That will at least mitigate reflection problems.

Agree with the Maggie's having less sidewall reflection problems. I removed my acoustic panel for the first reflection when I had the LRS+ in my old office. I got a pair of Mini Maggies yesterday for this same reason but for an even smaller room than the LRS+.

My DSP solution with the convolution filters is a one and one solution without any visible cosmetic changes to the apartment.

@OP you can generate convolution filters for your daughter’s room yourself with REW (open source software, free) and the aforementioned $100 mic.

Then, instead of expensive roon or JRiver you can run Daphile (Linux-based, open source, free) on the same suitably minimally configured PC you would need to run roon on anyway, load your convolution filters in Daphile, and voilà.

Not sure about the cost of ROON these days but I bought a lifetime subscription 10 years ago for $450

It’s $830 right now.

Good advice from @yyzsantabarbara as usual.

$830 for Roon is one of the best things a hard core audiophile who is also a music lover can buy.  I did.   The DSP using convolution filters and all the rest can be best thought of as a priceless bonus feature!!!

I use multiple third party convolution filters for specific headphone models and several I created myself with REW for various rooms in my house where I listen.

@grislybutter 

they are lacking basic info to understand what you need.

What I need is clearly stated in my post, isn’t it. 
I was asking if anybody had experienced setting up a system in such conditions.