Picture quality has improved enormously over the past decade. Sound has had a harder time of it, and the reason is physical rather than technical.
Speakers need air behind them to move. A television that is a few centimetres deep has almost none, and the speakers usually fire downwards or backwards rather than towards you. That is not a design failure so much as a consequence of everyone wanting a thinner screen.
So the question is not whether built-in sound is compromised. It is whether it is compromised enough in your room to be worth doing something about.
What people actually notice
Complaints about TV sound tend to be specific rather than general.
Dialogue is the big one. Voices sit at frequencies that small drivers reproduce reasonably well, but they get buried underneath music and effects, particularly in drama and film where the mix is designed for a cinema.
Then there is the volume swing. Quiet conversation needs the volume up, then an action scene arrives and it is far too loud. That gap is wider on a small speaker because it has less headroom to work with.
And there is bass, or the absence of it. Low frequencies need to move a lot of air, which a flat panel cannot do, so anything below a certain point simply is not reproduced.
Try the settings first
Before buying anything, it is worth checking what the set is already doing.
Most televisions ship in a sound mode designed to sound impressive in a shop. Standard or Music modes are often cleaner than the surround-style presets, which add processing that muddies dialogue.
Many sets also have a dialogue or speech enhancement option, which lifts the vocal range specifically. On a set that is otherwise fine, this alone sometimes solves the problem.
Night mode, sometimes called volume levelling, narrows the gap between quiet and loud. Useful for evening viewing in a flat, and it addresses the volume swing directly.
If those changes fix it, you have saved yourself a purchase. If they help but not enough, a soundbar is the next step.
What a soundbar changes
A soundbar is a single unit containing several drivers in a cabinet with actual depth, positioned to fire towards the room rather than away from it.
That gets you three things. Dialogue that sits clearly above the mix, because there is a driver doing that job properly. A wider stereo image, so effects have somewhere to sit other than the centre. And real bass, either from drivers in the bar itself or from a separate subwoofer.
Most bars come as either a single unit or a bar plus wireless subwoofer. The subwoofer makes the largest difference to how substantial things sound and is also the part most likely to annoy neighbours, so consider the building and not only the room.
Connecting it
This is where it gets slightly technical, and it is worth knowing before you buy.
HDMI ARC, or Audio Return Channel, is the option to look for. One HDMI cable between the television and the bar carries sound back from the set, and it also lets the TV remote control the bar's volume. Check which HDMI port on your set is the ARC one, since it is usually only one of them and it is labelled.
Optical is the common alternative. It works reliably and carries stereo and basic surround formats, though it will not pass the higher end formats and it does not handle remote volume control in the same way.
Bluetooth is available on many sets and bars. Convenient, though it can introduce a small delay between picture and sound, which becomes noticeable on dialogue. There is more on this in the guide to TV and Bluetooth.
Matching the bar to the room
Bigger is not automatically better.
A large soundbar with a substantial subwoofer in a small room produces sound that overwhelms the space and needs to be run at low volume anyway, which defeats the point.
As a rough guide, match the bar roughly to the width of the screen so it looks right, and think about the room size when deciding whether a separate subwoofer is worth it. A small living room or a bedroom is usually served well by a single unit.
Placement matters too. A bar sitting inside a closed cabinet loses much of what it was bought for. Directly under the screen, with clear space in front, is what these are designed for.
Where built-in sound is genuinely fine
Not every situation needs a bar.
A bedroom set used mainly for news and daytime viewing rarely does. Nor does a set in a caravan or motorhome, where the listening distance is short and space is at a premium.
Some televisions also handle audio better than the category average, with more capable drivers and tuning that prioritises speech clarity. Cello's Perfect Pitch Sound is built around exactly that, which is worth knowing before assuming an addition is required.
Deciding
Change the sound mode and turn on speech enhancement. Watch something you found hard to follow. If dialogue is now clear and the volume swing is manageable, you are done.
If it is still a struggle, a soundbar connected over HDMI ARC is the straightforward fix, and it does not need to be an expensive one to make an obvious difference.
You can browse the range at Cello Electronics or read more in the Knowledge Centre.