Room Size And Acoustics Explained

Room Size And Acoustics Explained
When you’re deciding which system to go for, this is probably the most important thing to consider.

It’s not just about a system being unable to fill a larger room, or a system that is too big swallowing the space in a smaller room and muddying the sound – not to mention taking up actual physical space with speakers and speaker wire. It’s what’s in the room itself.

Ideally, we’d all have a dedicated rectangular media room, with a listening position on a comfortable couch (with La-Z-Boy functionality and built-in cup holders, if you please), with walls that have been acoustically proofed, and speakers that are in precisely the right position. But most of us don’t. The vast majority of us don’t. For most people, the 5.1 or 7.1 system will be installed in a lounge or living room, and it will be filled with objects that will do funny things to the sound.

Bookshelves. Coffee tables. Vases. TV stands. Paintings. The bicycle that you’ve told your ten-year-old a million times not to leave in the living room. On top of that, there’s a pretty good chance your couch is probably pushed up against the wall, or at the very least, not exactly in the ideal listening position for the space. You might want to position rear speakers on speaker stands behind you, but they might very well get in the way.

Broadly speaking – and we really are talking very broadly, because acoustics is a vast science – there are objects that are good for sound, and objects that aren’t. A full bookshelf does good things to sound, because it absorbs the majority of the soundwaves, allowing you to hear what’s coming out of the speakers more precisely without it being muddied by reflections. Ditto for couch cushions, drapes, beanbags… Anything soft or uneven, really. On the other hand, walls, ceilings, paintings – anything flat and reflective – is going to complicate things as they reflect sound waves back into the room. In extreme cases, two parallel walls will create what is known as a standing wave: a low-frequency resonance that pops up as sound is reflected between them.

Ultimately, a good way to approach it is as follows. Evaluate the size of your room – anything up to 350 square feet (roughly) will be just fine with a 5.1 system, while anything above that would almost certainly benefit from a 7.1 system. Take a look at what you have in the room, and if possible, try to maximise bookshelves and soft furnishings (especially the bookshelves, because books are cool). Then pick the type of system that suits the size of the room.

And look: we know this is inexact. We understand that. Every single room is going to be different, and all we can do is provide some general principles. As long as you’re aware of them, and pay attention to your surroundings, you should be fine. If you’d like more guidance, check out these setup diagrams from Dolby.

A word on subwoofer placement. Placing the surround speakers is relatively simple: centre speaker under the television, front speakers on either side, and side speakers on the left and right of the listening position. Rear speakers behind it (for 7.1), roughly mirroring the position of the front speakers. But the subwoofer needs to go at floor level, Which opens up a whole can of worms.

Traditionally, the subwoofer is placed on one side of the TV, or in the corner, or in some cases along the side of one wall, pointing inwards. If you can, try to keep it close to the front speakers, which will help the illusion that the bass is coming from there. A good way to fine tune placement is as follows: put the sub, wired up, in your listening position – we know it’s weird – then, with something playing, walk around the room, or even crawl around at floor level. See where the bass sounds best. That’s where you want to put your subwoofer. And just remember: good base isn’t just loud, it’s also rounded, clear, and accurate. It shouldn’t blow your head off. Or your neighbours’.
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