How to eliminate reverb when recording sound in an echoey room

Feb 9, 2018

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

How to eliminate reverb when recording sound in an echoey room

Feb 9, 2018

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

Join the Discussion

Share on:

Some of you might think this is some magic bullet post processing trick to remove reverb from audio files. But it’s not. No, the only way you’re going to be able to get rid of that echo in your sound is to solve the issue at the source. That means treating the room to eliminate it completely. In this video, DIYCameraGuy, Michael Lohrum shows us some of the ways we can get fix a room so that echoes don’t happen.

YouTube video

The opening of the video is the perfect illustration of an echoey room. It’s an absolute worst case scenario, and you can hear it in the recording. It has a hard concrete floor, bare smooth painted walls and ceiling, with lots of surfaces for sound to bounce off.

Sound is a lot like light. If you bounce a flash of a smooth glossy white surface, it’s going to reflect right back. But if you shine that light at a rough black surface, it’s mostly going to be eaten up and not impact your shot. It’s the same sort of thing here. Smooth hard surfaces reflect back a lot of the sound, causing echo & reverb. Rough soft surfaces absorb and scatter the sound, minimising the amount of echo your microphone hears.

As Michael walks into the next room, the difference becomes immediately obvious. This is the room Michael plans to use as his recording studio, and it’s already had a little treatment. Michael admits it’s not perfect, but it’s a massive improvement already.

Michael says that the key to absorbing the sound in a room is to use items that have a good weight to them but allow air to pass through, bounce off a wall, and then pass back. Unlike a direct reflection off the wall, that sound is very diffused by the material in between. The echo eventually becomes almost non-existent. Or at least, it’s quiet enough that it’s not impacting your recording.

The ideal solution for something like this is sound blankets. They’re fantastic for location work as well as permanent recording setups. But, proper sound blankets are not inexpensive. At around $220 for a 6’x4′ blanket, you might need half a dozen or more to treat a relatively small room. In a pinch, Michael says that moving blankets will work. However, they’re much lighter, so they’re not going to be as effective. But they’ll still be better than a completely untreated room.

Heavy clothing and towels can also be good cheap substitutes for sound blankets. Again, they won’t be quite as good, but better than an untreated room. Or you can layer up multiple towels and make your own DIY sound blanket panels, as Nate Perks did. Nate’s panels are designed for a more permanent installation, but if you can find a way to mount them to stands, they can even work on location.

For more permanent setups like a home studio, or even just around your computer to record sound, acoustic foam is another option. These are available in varying sizes, styles and price points for dealing with different types of sound. Some deal better with certain frequencies than others. So, if you’re going the acoustic foam route, you’ll want to do some research to get the best results.

Ultimately, the goal is to intercept the sound so that it doesn’t reflect directly off hard smooth surfaces, and sometimes that can be as simple as opening a door. After all, sound can’t bounce off an open space. Just make sure it’s not too loud on the other side of that doorway first.

Some degree of reverb can be taken away in post, sure, but it’s problematic and the software can be very expensive. It’s going to be much less of a headache to just eliminate it from the equation altogether before you hit record.

Filed Under:

Tagged With:

Find this interesting? Share it with your friends!

John Aldred

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

Join the Discussion

DIYP Comment Policy
Be nice, be on-topic, no personal information or flames.

Leave a Reply

Your email address will not be published. Required fields are marked *

3 responses to “How to eliminate reverb when recording sound in an echoey room”

  1. Jimmy Harris Avatar
    Jimmy Harris

    Sound blankets aren’t the “proper” method to solve the problem. Broadband absorbing panels, like those made of Owens Corning 703 are. But they are even more expensive. A better option is to use the proper microphone so it ignores the reverbs and just pics up the source signal. Which mic will do this depends on the room and the needs for filming, so there’s not a one-size-fits-all solution here. You can also try blocking the reverb at the mic instead of in the whole room. This involves some broadband absorbers (called gobos, oddly enough) positioned around the mic to reduce off axis pick up. So rather than trying to kill all of the reverb in the room, you’re just trying to kill the reverb that the mic pics up. There are also other techniques that involve multiple mics positioned in different places in the room and adding them in phase to increase the source signal to reverb ratio, making the reverb less noticeable.

    Acoustic foam isn’t worth the cost. It ugly, expensive, and very ineffective. It’s only use is a sales gimmick to amateurs who haven’t done their research. I used to run a recording studio, so I’ve got a lot of experience with this stuff.

    1. Renato Murakami Avatar
      Renato Murakami

      Thanks for the insight Jimmy… let me ask you directly.
      Any tips for a cheaper, ghetto, acoustic insulation solution for a room?
      Long term plan I guess, but I’ve always been thinking of turning a spare room in my apartment not only to record stuff, but mostly to listen to loud music without bothering the neighbors… xD
      As far as I’ve heard, multiple layers of heavy blankets or something similar. That acoustic foam that you find multiple DIY videos talking about isn’t dense enough to insulate anything by itself, and if you can do proper acoustic insulation it’ll kinda take care of reverb by itself.
      The picture I have is that of… a padded room. :P Which wouldn’t be inadequate for me listening to loud rock and classical music in it anyways…

      1. Jimmy Harris Avatar
        Jimmy Harris

        Unfortunately, there’s no cheap way to insulate sound. Thick concrete walls, or building a second, smaller room inside the big room that is uncoupled from the outer room are about your only options. Any directly coupled surface or hole that air can escape through can transmit sound. So if you want to listen to loud music without annoying neighbors, I suggest headphones.

        As for the cheapest DIY method of blocking reverb, I’d suggest the padded moving blankets that U-Haul sells. And hang them up with wrinkles and folds, like curtains, to give them an irregular surface. Either that, or build some frames stuffed with Owens Corning 703, or Rockwool rigid fiberglass insulation and cover them in cheap fabric, bound with staples.