Recordings and soundtracks contain the reverberation signature, or room tone, of the space they were recorded in (concert hall, recording studio). In a movie soundtrack, the recording contains the reverberation signature the director and audio designer conjured up. Either way, the reverberation has been provided for you, so it makes sense that a listening room that is overly reverberant will interfere with the sound the artist intended.
As sound spreads out from the loudspeaker it will eventually reach a wall and then reflect toward you. First reflections, also known as primary or early reflections, are the most powerful reflections to reach your ears; they are typically destructive. Secondary and later reflections are typically so weak they don’t pose a problem in a normal living space, but they do add to a general sense of space or ‘airiness.’ No one cares about the reflections they can’t hear, but the reflections they can hear will muddle up the direct sound, diminishing detail and the overall sonic clarity of the track you are listening to.
Sit in your chair in your prime listening position and look at your speakers (L-C-R), then look at the walls to your left and right. Somewhere along each wall the direct sound from the speaker bounces off the wall and heads for your ears – the first reflection. If the walls on your left and right are not the same distance from your speakers because of the way the room is laid out, the first reflection points will be different for each side. If one of the walls is relatively far from your position, reflections may not be an issue.
Sit in your chair in your prime listening position and look at your speakers (L-C-R), then look at the walls to your left and right. Somewhere along each wall the direct sound from the speaker bounces off the wall and heads for your ears – the first reflection. If the walls on your left and right are not the same distance from your speakers because of the way the room is laid out, the first reflection points will be different for each side. If one of the walls is relatively far from your position, reflections may not be an issue.
Keep in mind that there is a different first reflection point for every possible seating position. There are also four first reflection points for every seating position: the two walls (lateral reflections), the floor and the ceiling. Floor reflections are very rarely a problem because of their low angle, so your best practice is to simply place a carpet or rug on the hard-surface floor between you and your main speakers just in case. If the ceiling is high enough ceiling reflections won’t be an issue, but in a standard home listening environment, the same amount of attention should be paid to ceiling reflections as is paid to the lateral reflections.
Managing first reflections can go a long way toward making a vast improvement in how your system sounds and there is an inexpensive and easy way to find and treat them. All you’ll need is a friend and a mirror. Once you have secured a friend and a mirror, sit in the main listening position and have your friend run the mirror along the wall between the loudspeaker and you. At some point, you will see the loudspeaker reflected in the mirror – that’s the first reflection point. Mark it with a small bit of tape, move to the next seating location and repeat (use painter’s tape so it peels off easily). If your main listening positions are close to each other, you’ll find the first reflection points will all be somewhat close to each other. Repeat for the second wall.
Managing first reflections can go a long way toward making a vast improvement in how your system sounds and there is an inexpensive and easy way to find and treat them. All you’ll need is a friend and a mirror. Once you have secured a friend and a mirror, sit in the main listening position and have your friend run the mirror along the wall between the loudspeaker and you. At some point, you will see the loudspeaker reflected in the mirror – that’s the first reflection point. Mark it with a small bit of tape, move to the next seating location and repeat (use painter’s tape so it peels off easily). If your main listening positions are close to each other, you’ll find the first reflection points will all be somewhat close to each other. Repeat for the second wall.
Once you’re done, you’ll have a bunch of tape on the wall pointing out the first reflection points for each seating location. Simply get yourself a nice absorptive panel from a custom acoustic paneling company and hang it so that it covers the marked reflection points. If studio chic is not your aesthetic you can use that artisan wool macrame wall hanging thing you bought at a street fair years ago that you never really knew what to do with, or any other decorative item that is more absorptive than reflective. Anything that will absorb sound and not scatter it will work. Paintings, artisan wool macrame, or whatever creative idea you can come up with will do the trick. Mirrors, glass, wood ornaments and the like are not absorptive so avoid them in the first one-third of your room. Save the reflective surfaces for the rear two-thirds of the room to keep your room sounding lively and spacious.
That’s it, now that you’ve got your first reflections tamed, you’re one step closer to getting everything you can from your audio system.
That’s it, now that you’ve got your first reflections tamed, you’re one step closer to getting everything you can from your audio system.
By Jack Sharkey for KEF
