RealTraps News - More Myth Busting
Expert acoustic advice from Ethan Winer

Acoustic Behavior Is Linear

Contrary to what some people believe, the acoustic properties of both objects and rooms is linear and behaves identically at all volume levels. Whatever frequency response you hear from your speakers in the room, that response is the same whether the speakers are playing soft or loud. The same applies to time-based effects like reverb and ringing. Reverb time is defined as how long it takes for sound to decay by 60 dB, and it takes the same amount of time at all volume levels. A waterfall plot showing low frequency ringing in your room will have the same shape no matter how loudly the frequency sweep was played while measuring.

The Fletcher-Munson Curve changes the perceived frequency balance we hear at different volume levels, with the response sounding more flat at louder volumes. This is a well-known effect, but that's just how our hearing works - it doesn't change what actually happens in the room. Likewise, at a low volume reverb can decay below audibility or below the noise floor before it has dropped by 60 dB. So it might sound like the reverb time is shorter at low volume, but it's not really.

The only exception occurs at very loud volumes, like ten feet away from a jet airplane engine. At such high volume levels the air itself compresses slightly from the extreme pressure. But that will never happen in your home studio or hi-fi listening room. Another exception is doors or windows might buzz and rattle only at loud volumes. But that too is a different issue and is related to friction.

This room response would be identical whether the speaker played softly or loudly while measuring. Note that this low frequency response is typical for a room without any bass traps.

Room Correction Revisited

The first product I'm aware of that claimed to correct room acoustic problems electronically is the original Audyssey MultEQ system. This very expensive equalizer claims to flatten the response and reduce ringing over a usably large area of the room. But basic physics dictates that the more EQ you apply to flatten the response, the smaller the physical area that's improved. Not only are other nearby locations improved less, many are made even worse!

So I was skeptical of the Audyssey claims, and with the help of a local friend I measured his Audyssey MultEQ system. That was in 2007, and I shared my findings in this Audyssey Report on the RealTraps web site. As you’ll read there, most of Audyssey's claims were shown to be untrue. In the years since, several other companies have jumped on the bandwagon offering room "correction" products, and a few loudspeaker manufacturers now incorporate room EQ into their active models with claims ranging from modest to physically impossible.

When I link to my Audyssey Report in audio forums people sometimes counter that room correction has evolved and works much better now. So clearly it was time to test again. This time I assessed Dirac and Acourate, and published the results on the professional recording web site ProSoundWeb. As you'll read there, the laws of physics still apply.

New Install at Clemson University

And finally, RealTraps recently treated the audio learning lab at Clemson University with MegaTraps, MondoTraps, and RFZ Panels. Their choice of gray panels with black frames looks stunning. But more important, lab director Hamilton Altstatt wrote to tell us, "We installed everything and it works and sounds great; definitely improved the acoustics, and looks really slick and matches the furniture!"

That's all for now. Until next time I remain your faithful RealTraps friend and advisor.

Ethan Winer

RealTraps was founded in 2003 by Ethan Winer and Doug Ferrara, and is now owned and managed by longtime employee Sean Kollar. Sean handles the day-to-day operations at the factory, and Ethan still pitches in to help customers with technical and pre-sales advice by phone and email. Ethan is well known throughout the audio industry for his technical articles in audio and computer magazines, and his popular book The Audio Expert published by Focal Press is now in its second edition. Sean is amazing whether playing the drums or the electric guitar.

General product information: http://realtraps.com/
Contact by email: Ethan Winer
By phone 10:00 am to 5:00 pm eastern time: toll-free 866-RealTraps (866-732-5872, local 860-210-1870)

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