For big-screen TVs, surround sound is a must. But, since very few modern living rooms host perfect acoustics, you'll have to be willing to make compromises. In this article, we'll give you the background know-how as well as some tips and tricks.

It takes some determination, but even large open spaces like this luxury villa's living room can have decent acoustics.

The reverberation time should be less than 0.5 seconds, so you need to sufficiently dampen the sounds. You can calculate the time using a software tool from Jörg Hunecke.

Maximized direct sound and minimal reflections should originate from the front speakers. Reflections from behind are generally not a problem.

Make the sound come from a soft place to a hard one -the front of the setup should be installed near few reflective surfaces.

Try to use solidly constructed furniture, reducing vibrations and other interferences.

Wherever possible, bring home the device and try it out before you buy. Do not simply rely on how it sounds in the dealer demo room.

If you're just planning your home-theater experience and need some basic information about home-theaters, it may be worth checking out our "Home-Theater Guide", which advises on projectors, TVs, and other components.

	If possible, position the TV, center speaker, and front speakers on the short side of the room.

If you're building your own home, you'd likely include a home-theater. But this article applies to the majority of us who are tied to a fixed floor plan. Ideally, you should choose the smaller side of the living room for the front of the home-theater. This gives you plenty of space between the viewer and the screen and plenty of room to position the speakers. As much as possible, the right and left front speakers should be the same distance from the listening position. The same is true for the rear speakers, whether you have two, three, or four of them. This eliminates gaps in the surround sound.

This spacious living room doesn't have a short side, but the solution provides the necessary characteristics: a dividing wall for the home-theater and a dampening chimney housing to the left, which also houses the subwoofer.

	You can dampen undesired reflections from the front speakers using soft fabrics such as curtains.

The era of square-shaped, box-rooms houses is over. In many cases, everything clusters around a central living area, which opens in a number of directions: down a set of stairs to the basement, up to a dormer window or mezzanine floor, and sideways to a kitchen or dining area.

For example: The room has a large glass frontage on the left, and cupboards and shelving to the right with open, irregular surfaces. One side strongly reflects sound from the speakers; the other side dampens the sound to a similar extent. If the movie-viewing area is open on one side, you get a similar effect. This disturbs the homogeneity of the sound and upsets the listener's ability to localize noises.

The front side of the living-room home-theater, where the screen and speakers stand, should be fairly soft. So, there should be no hard walls behind the speakers, but rather something that will dampen the sound, such as a fabric cover. This reduces the reflections from the front that arrive only slightly after the direct sound, and are therefore extremely irritating. Conversely, a hard wall behind the listeners has a diminishing effect, since the ear more easily blocks posterior sounds.

The key to great acoustics: The ratio of direct sound (from the speakers) to reflections (from a wall, for example) should favor the speakers. It helps to angle the speakers inward, toward the listening position - or simply move them closer to the audience.

You can also dampen the reflections. With a window, hang curtains or even Venetian blinds made with a soft fabric. Bear in mind: You only need to dampen the region producing the reflections in the listeners' direction - as a rule, this is where the incident angle of the sound is equal to the angle of reflection. Admittedly, it's impossible to be able to entirely eliminate reflections.

Luxury does not always make life easier: The bass can get caught in adjacent rooms or staircases and start to produce booming effects.

Now let's tackle the bass: In open-plan living areas, it can get caught in staircases or corners, just as in a loudspeaker's bass reflex port. The result: The bass will produce booming effects. No ingenious positioning will help here, since the deep frequencies will penetrate any obstacles, including curtains and dividing walls. The only solution: You have to find out which individual bass frequencies cause the droning, and remove them at the playback stage.

But this means you need a room calibration, either with the help of an expert, or using an AV receiver's automatic calibration. Since bass sounds always consist of a range of frequencies, you rarely notice the absence of the one responsible for the booming - but you will notice the absence of that irritating droning noise.

A further problem affects the surround. A homogenous field of sound relies on reflections from the walls, especially if you are using dipole speakers. If the walls are too far away, or missing altogether, uniform sound can be difficult to produce.

Direct radiators placed too close to the listeners can create odd effects, such as the sound of rain coming from only one corner of the room rather than all around. The farther the listeners from the surround speakers, the better.

Consider using the ceiling for reflections, but only if it‘s not too high. It can also help to switch from a 5.1 to a 7.1 setup, since this just has more sound sources. It is impossible to decide theoretically - or even using a measuring device - which is the best solution, or: Trial and error is the only way to find out.

	Modern living rooms' hard, bare surfaces increase reverberation and harm overall sound. Acoustic plaster or absorbers can help reduce reverberation.

Reverberation time is integral to a room's acoustics. Ultimately, it depends on the surface of the walls, floor, and ceiling. In a room with a long reverberation time, sounds appear very loud; while short reverberation times make sound appear swallowed, reducing the perceived loudness. Professionals clap their hands when they enter a room and listen to see what happens - if anything at all.

An indoor swimming pool is a great example of long reverberation times. For movie sound, these conditions are simply awful, so it seems stupid that current interior design trends are headed the same way, with their relatively large number of hard, bare surfaces. Acoustic-friendly textiles such as plush or velvet and thick carpets are currently very much out of fashion.

Technically, the reverberation time, or the time taken for a noise to fall to 60 decibels, should be less than 0.5 seconds. You can calculate this approximately, for example, using a tool developed by Jörg Hunecke, an acoustician from Munich. The user inputs the size of the room, the properties of the walls, the furniture, and the intended use; the program will then quickly indicate the problems areas.

The Acoustics Calculator by Jörg Hunecke calculates your living room's reverberation time. Seen here: the version for drywall.

There are numerous options to improve the situation, but these are not always easy. For example, there is special acoustic plaster that dramatically reduces reverberation. If the walls are made of glass and concrete, a ceiling covered with this special plaster is often the only way out. In terms of dry construction methods, you can buy appropriately optimized drywall sheets, for example.

Improving your acoustics retroactively, is more difficult. Traditional acoustic absorbers do not fit in the living room, but there are variants available, such as those from Thomas Fast in Stuttgart (Fast Audio), specifically intended for this kind of integration. These have special surfaces with a choice of images printed on them. Alternatively, you can hide the absorbers behind a bookcase, a sofa, or a painting. The picture will hang a couple of centimeters away from the wall, but you'll hardly notice.

A way out of the crisis: Absorbers will reduce the reverberation. Alongside professional absorbers for the recording studio, Stuttgart's Fast Audio offers a version sporting chic designs that look more at home in the living room.

	You should use the heaviest, best-made furniture possible. Lighter objects can vibrate or rattle, ruining your movie experience.

An empty room is an acoustic catastrophe, no matter what shape it is. When you think about it from this point of view, furniture isn't the problem - it's the solution. More than anything else, room furnishings dampen the reverberation, making acceptable sound actually possible. More furniture and textiles generally improves dampening - it is just a question of placement.

When direct sound from a speaker and reflections from the floor or wall are close together properly positioned furniture may be the answer. It could be a rug in front of the speakers or a bookcase beside or behind them. The aim is to have soft, irregular surfaces nearby, which dampen sound more than hard, flat ones.

Not ideal for the home-theater: Flat-pack furniture, like this unit from IKEA, tends to drone, spoiling the sound. Better to stick it in the hallway.

Interior design, however, can also harm the sound - home-theater involves a lot of high-energy moving air. Everything that's not nailed down can vibrate, rattle, or drone - glasses in a cupboard, doors on a wall-unit, or even the windows. You can track these effects down using a "Sweep" test signal, which moves across the entire frequency spectrum. You can usually localize and eliminate the problem after a few passes. Generally heavy, well-built furniture will cause you no problems. With thin, light objects like flat-pack furniture, you're risking spoiling your movie.

	Help for the living room: An AV receiver with automated calibration eliminates at least the most obvious problems.

Newer AV receivers' automated calibration is a blessing for living-room movie-fans. It's no cure-all, but often helps eliminate the biggest problems, and requires no extra effort. First thing to consider: The bass playback, on which you can eliminate various basic problems. You could ask an acoustics professional to carry out the perfect corrections, but be prepared to pay.

Still, the point remains: Calibration systems can only repair specific errors. We recommend approaching fundamental acoustic problems differently. If you have the option, use acoustic absorbers rather than relying on electronics to cap problematic frequencies.

Even the best acoustics will only sound as good as your home-theater's components. If you want great sound in your living room, first your amplifier and speakers will have to do a decent job. If you then follow the basic rules of acoustics, you can experience excellent sound, even in the imperfect modern living room - without upsetting the design or comfort of your home.

It'll be fine: Even with such a huge glass frontage, you can still set up a respectable home-theater. Still, you will definitely need curtains over the window for true movie enjoyment.

PS: As a closing tip from our own experience: Make this a family project and get everyone involved. This could be a great reason to invest in some new furnishings or just give the room a little facelift. As always discretion and mutual respect will get you closer to acoustical perfection.