Flutter Echo

Saturday, June 4th, 2011 | by

What is flutter echo?

It is a series of rapid, repeated reflections caused by soundwaves bouncing around between parallel reflective surfaces. It can happen in any untreated space, but any smallish room with a hard floor is especially susceptible to it.

My den has it bad. Standing near the center of the room, I recorded a series of handclaps. This is what a flutter echo sounds like:

Flutter echo, full speed

I used compression on this sample to bring out the sound of the echo. It sounds like a metallic ringing. In this particular room, the echo actually moves around, up and away, into one of the corners as it fades.

(In case there are any mic nerds in the audience 😉 , I must note that I recorded this with an Avenson Audio STO-2Avenson Audio STO-2 omni condenser, pointed at the ceiling in the center of the room.)

If this sound is present in your tracking room, it will color the recorded tracks. And if it’s present in your mixing room, you’ll be fighting to EQ out a sound that isn’t in your mix, but only in your room.

Here’s the same flutter echo sample as above, at half-speed. You can more easily hear the individual echoes this way:
Flutter echo, half speed

If you have flutter echo, how can you fix it? In short, you need to break up the parallel reflective surfaces. Acoustic panels or foam, diffusors, drapes, furniture… there are a thousand ways to do it, and a thousand acoustic treatment vendors willing to help. The nice thing about fixing acoustic reflection problems is that once they’re gone, all your gear will sound better.

Posted in Acoustics | 3 Comments »

3 Responses to “Flutter Echo”

  1. Randy Copinger

    June 7th, 2011 at 8:17 pm

    This is a helpful post with clear audio examples Matt. Thanks. The good news is, flutter echo is the easiest of all acoustical problems to fix. Sometimes all you need to do is hang some pictures, add a few hanging plants, or otherwise just clutter up the path of the reflections with something you might like to see instead of a bare wall. Yes, you can purchase expensive acoustical products for the greatest efficiency in eliminating the echoes, but I wouldn’t.

  2. Aaron Lyon

    July 22nd, 2011 at 9:39 am

    Another cheap solution: If you have bookcases on your walls, you can make a diffusor by arranging the spines of the books very randomly!

  3. Steve Hebert

    January 31st, 2012 at 9:52 am

    Love the bookcase idea. Thanks

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