• Record echo with a balloon pop or a snare hit

• Find the echo time

• Derive the echo path length

• Put some absorption or diffusers on the wall that matches the path

Some acoustic panels on the walls / ceilings would greatly help to reduce that echo. I recently made a video on how to make such panels, if that would be of interest to you: https://www.youtube.com/watch?v=eb-AOFzfiXA

You"ll definitely want to hang 2/3 above the stairs on the wall and 2/3 on the wall behind the drum set.

I don't know who told you that, but acoustic panels are not a last resort.

I think you should elaborate/describe what you call an echo.

Echoes are audible, single or multiple repeats.

In a room as small as this, single reflections usually cannot be disciminated from the direct signal, but multiple reflections are audile. Late reflections are audible as reverberation.

If your problem is actually a single or multiple reflection, follow the advice of u/jordanlcwt, if you cannot locate a problematic wall by simply claping your hands and listen (which usually works very good).

To reduce reverberation, you need absorption, Rugs only provide sound absorption at high frequencies. Thicker absorbers work better,

Run two steal cables / wires the length of the room then just place the acoustic panels on top - kind of like a plank bridge.

The panels will absorb sound on both sides as there’s no hard surfaces - so anything bouncing off the ceiling and from below.

I would suggest: as even a distribution of acoustic treatment as possible throughout the space. This would mean applying wall panels to the black beam sections, the end wall and perhaps along the top of the wall with the artwork/screen to the right. Go for as high a Class as you can for wall panels, Class A if poss. FYI you can get wall panels that are screen printed with custom photos or art...

Ideally, you would also put hanging baffles or rafts below the ceiling and in such a way that the ventilation is not compromised. Baffles/rafts would be the most effective as they provide relatively high areas of absorption, but appreciate this will be difficult to do yourself.

You may be OK treating the walls only, as you have a carpet and large open spaces to the left, but the ceiling may end up being the limiting factor if you cannot treat it.

Make things that are hard into things that are soft. I don't want to say "carpet the walls" but next time you are in a movie theater walk over to a wall and examine it. It's fabric over foam.

Hang rockwool panels from the ceiling parallel to the walls.  It should control a decent amount of echo.

Something like this (I described the solution, AI generated the photo):

https://imgur.com/a/miuBX0b

Presumably you’re only interested in reducing reverberation for speech and general noise, not turning into a music listening space? If so that’s a benefit because it means you don’t need to worry about low frequencies too much, which makes it easier as thinner treatment will still do want you want.

Hiding treatment can work, but you still need some space between the treatment and the nearest surface to allow sound to propagate. So the underside of a table is great, that would absolutely help. Underside of cabinets are less likely unless there is at least 8-10 inches between the cabinet bottom and floor.

Rugs and soft furniture really help too albeit they might not go with the minimal aesthetic it sounds like you are after. Alternatives include acoustic plaster, which is expensive but really works and looks like a normal slightly textured plaster. Doing your whole ceiling in acoustic plaster would do the job.

Also wood slat walls look good and modern and if you fill a whole wall they don’t look like ‘treatment’. https://akuwoodpanel.uk/collections/wooden-wall-panels?utm_source=google&utm_medium=cpc&utm_campaign=woodenslatwall&gad_source=1&gbraid=0AAAAApZboL-bPjSQMQN8NoIHYPz_S_sSy&gclid=EAIaIQobChMI9oaalKTPjAMV8pdQBh0OzxqOEAAYASAAEgL0hvD_BwE Acoustically they tend to have quite a thin layer of absorption so not that great for music spaces but would work well for general domestic noise.

Hope that’s useful.

You need mass in the room.

If you have shelves or cupboards you could put rockwool blocks on top of them.

You could get a new rug.

You could hang a tapestry on a wall.

Could you hang a cloud panel from your ceiling.

You could buy some of these sound isolating panels. They come in white, too. It is not necessary to fill the room. But with 4 or 5 in each wall the echo would go down significantly. You could even ask for personalized advise in some hardware stores near you. Face to face is sometimes easier to help you. The panels are something I would go for.

Aside from it you can just put those styrofoam plates on the wall, it is cheaper and can reduce the echo, too. Put them high enough for your cats to not reach them. Any painting you would like to hang there would do it, too. Any shelves, too.

Fabric absorbs sound. So carpets, tapestries, framed canvas pictures, that sort of thing. Some chunky curtains may help too, light blocking curtains are also frequently sound blocking, so even if they’re hung up on either side of the window it could absorb some of the sound bouncing around.

Definitely a large rug will take care of that problem. Get the biggest you can fit in there. No point in getting a dinky little rug for a pretty small room.

Start with a rug then add pictures to the walls

The echo is caused by hard parallel walls in a box. The sound bounces from one wall to the other. You need something that will absorb sound. Your best solutions are carpets and drapes. Fabrics will deaden the sound.

Those cheap foams only affect the highest frequencies, what you want are some proper acoustic panels, 2" thick at least.

There is a free software you can download called REW, that allows you to measure the room's response. You will need a USB mic connected to a laptop or similar. Then take some readings to understand what exactly is going on in your room. This will allow you to treat the issues more effectively, since you now know what you are trying to cure. Start with optimizing seating and speaker position. Get that dialed first then measure some more and start treating. As others pointed out, insulation material is you friend. Thicker and at room boundaries (corners) for bass, first reflection points for echo, etc. Don't ignore the type of furniture either. Some things like TV screens or glass coffee tables are reflective and can make things worse. You might enjoy the book called "Get Better Sound" by Jim Smith. Lots of good information to get the most out of your system.

foam doesn't do much. check out gik acoustics or ats. they use various types of insulation, rockwool, owens corning etc

You can buy sound absorbing foam from hardware store chains like Home Depot. If recording studios use acoustic foam, then you know they must work.

I have bookcases right across my back wall. Mixing up the book sizes makes an excellent diffuser to scatter the echo. I also brought each successive unit forward about an extra 15mm to simulate a slightly angled wall to stop reflections just going back and forth. No idea how well each element works, but the results are very good to my ears. But it’s a bit livelier than my cinema room, more like a performing space. That said, as the room’s filling up more the difference is less.

Putting literally anything up on the walls and floors will help a lot; Tapestries, hanging sculptures, rugs - Literally anything

If you've got a budget, simply call any one of the "acoustic companies" and they'll outfit you with some very fancy and appealing wall decor that should take care of things - will run you couple thousand, though.

- And where's the lunch so I can come?!

Cheers

Heavy molton curtains on the wall(s) and acoustic panels on the ceiling is the way to go on these kind of spaces.

Acoustic treatment on the walls and/or ceiling. Get something that looks acceptable or people will notice.

Absorption panels are your best bet. The tile is going to be a pain to deal with, so you'll probably need absorption panels on the ceiling as well.

The panels can be strategically placed to have maximum impact, keep in mind that a room that size will require a good amount of panels so it may get expensive.

Kintetics noise control (www.kineticsnoise.com) offers the best products for commercial and industrial spaces that I am aware of. Do remember that finishes are often the most expensive components of surface treatments. Companies like GIK offer good looking products for home use, but the prices for covering large walls effectively can put them out of range for a lot of larger venues.

Soft furnishings and a bookshelf. If you get acoustic panels please check they’re fire rated.

Couches, big cushions, carpets etc help absorb soundwaves. Since you don't have a lot of space you can try cork mats, on the floor or on the walls.

Definite plush carpets and maybe some kinda acoustic board where you speak

your rooms a box, hang a fleece blanket from walmart on the back wall, but hang it on a 10-15 degree angle....(as in it will be flat on the wall near your door but come out 6-10 inches on the wall near the window, You'll have to move your clothes closer to the window because some of the room is going to be eaten. Make sure it's a king sized blanket so it covers as much of the wall as possible... that should help quite a bit for like $20.

If you want to go crazy get another one that is all white so the light can go through it, and pin it to the 4 corners of your ceiling and allow it to droop in the center.

Not going to be the best way to do it... but it will be the cheapest and quickest

You need to fill up those walls

A mix of absorber and diffuser will do you good, but be mindful and understand that not all item sold as acoustic treatment will work across all frequencies. So you need to understand the range of frequencies that is problematic to you.. all in all if it’s too much of a hassle, you can always try and get closer to your speaker..

Also are you sure it’s not echo-y because of a setting that introduce echo or something? Honestly I don’t have a soundbar so I don’t know if that’s a thing.

But your description said it’s echo, not reverbation, which isn’t really supposed to happen unless you have gigantic room

Should be a lot of info about room acoustic treatment if you search this sub. You'll want to get a large area rug if you have hardwood. Treat your first reflection points which can be found by sitting in your main listening position while someone slides a mirror across each wall until you can see your speaker. Treating your rear wall will be important also as that can help with dialog clarity. Ceilings will help too but not always as practical.

Don't use cheap Amazon foam and just slap that on your walls expecting that to help even if you put it in the right spots. Plenty of info here on good materials to use, typically sound absorbstion insulation like rockwool. Can buy good products online or DIY it. You have a soundbar not a home theater so while I'm sure acoustic room treatment will help you may always have some limitations with dialog quality.

Leaving aside that your hardware questions are r/soundbars territory...that you have a silly soundbar trying to be clever in a massive, funky shaped space to mimic real surround sound is adding to the woes.

Look up acoustic treatment. Lots of soft furnishings to reduce reflections. Pay particular attention to the first order wall reflections, ceiling reflections, and floor reflections if hard floors.

Different treatments are needed for different sections of the frequency spectrum, so I think you have some reading / Youtubing ahead in your future. ;)