Acoustic Treatment For Your Listening Room: Part I

The construction of three new studios in the AIX building is almost complete. After over 6 months of work, the solid maple floors are installed, the sound proof laminated glass is in place, the door frames sealed with rubber gaskets, and the walls are getting covered with insulation and fabric. The only major things left was to complete involve the wiring, the ceiling cloud, setting up the equipment and furniture, and the actual “room tuning”. It’s been a long haul but as you can see in the pictures below, the room is looking really great.

The sonic characteristics of your listening environment are among the most important factors in determining the enjoyment of your sound system — and the quality of sound you experience. The size, the shape, the ceiling height, and the treatment of acoustic reflections and resonances are much more important than cables, clock regenerators, and the sample rate/format of your delivery format. I see a lot of pictures on Facebook showing rooms where audiophiles enjoy their music. Generally speaking, they are living rooms, entertainment spaces, bedrooms, basements, and occasionally dedicated listening areas. If you’re in the fortunate position to be able to custom build or modify a room in your house to maximize your audio listening pleasure, more power to you. I feel extremely fortunate to be able to enjoy and work in my dedicated, professional, acoustically tuned, audio studio. But this is what I do for a living.

So let’s turn our attention today to exploring how you might improve the sonics of your space. There are three things to be aware of when considering acoustic treatments: isolation, diffusion and absorption. I’ll be covering the basics over the next few posts but you might want to check out the chapter in my book “Music and Audio: A User Guide To Better Sound”, where I’ll be going into much more detail.

Isolation means that sound from one space or location will not impact any other spaces. Studios like the three new ones in my building must be designed and constructed to minimize “leakage” from the control room, isolation booths, main live room, drum booth, or machine room. While isolation is a very important concept in professional studios, it’s not as critical in consumer environments. Most homeowners or renters don’t have the resources or interest in building double walls, floating floors, or installing double glass, acoustic windows.

Diffusion breaks up radiating acoustic energy by breaking up the sound in terms of timing, phase, direction, and intensity. This is done by placing acoustic “diffusers” in strategic places in the room. For example, my main studio has a solid maple floor in the center monitoring area. I built a large, ceiling mounted diffuser to break up any sound that might bounce or resonate from the floor.


Figure 1 – The view of the AIX main control room showing the diffuser located above the main mixing spot.

Absorption deadens the reflectivity of a listening space. Professional studios are generally very “dead” sounding. Engineers want to avoid having the room place a large part in the ultimate sound that is being heard as they mix. Therefore, the walls are covered with fabric or sound absorptive panels. Acoustic energy hitting the walls doesn’t bounce back and distortion sounds coming directly from the monitor speakers.

We’ll take a closer look at these concepts and I’ll share some of the approaches we’ve used in the design and construction of the new rooms.

To Be Continued…


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

9 thoughts on “Acoustic Treatment For Your Listening Room: Part I

  • June 25, 2016 at 1:28 pm

    Hey, Mark

    Your e-mail newsletter provided me a wrong hyper-link to your website.

    ERROR 404

    Please have it checked out.


    George Lien

    • June 26, 2016 at 10:52 am

      Sorry George, which link was it? The one that goes to the book site worked…

      • June 26, 2016 at 11:55 pm

        This one at the bottom of the email Mark,
        “If you would like to leave a comment on this article, you can do so at the site at the bottom of this article page. Click here to visit that page.”

  • June 26, 2016 at 12:34 pm

    Now these are the kind of posts I like reading. I’m sure I’ll learn something in the next few newsletters.
    Thank you!

  • June 26, 2016 at 3:19 pm

    Hi Mark, the broken link in the email is in the last paragraph

    “ site at the bottom of this article page. Click here to visit that page.” The link is to which gets the 404 not found.

    I found this post particularly interesting, your comment about needing to mix in a “dead” space piqued my interest so much so that I read it to my wife. Her reaction was interesting. Our last theater was quite well isolated using inch thick drywall on the walls and 5/8 Firebar dry wall on the ceiling. Behind all the dry wall was R30 fiber glass insulation. The floor was concrete. Then we’d finished the rough construction it had at least a 15 second reverb time.

    To tame that, we put heavy carpet on the floor over thick rubber underlay. The walls were treated with 2 inch thick Bonded Acetate Fiber with two different cloths running the length of the walls above and below the chair rail. That was my wife’s idea and the result looked fabulous. The door into the theater was treated with 3/4 sheet of MDF glued and screwed to theater side of the regular door, and that was given a matching treatment of BAF, Fabric and chair rail. The ceiling was left painted without any acoustic treatment.

    It became a very quiet space to sit in. Not quite anechoic, but close.

    Net result was a fabulous listening room. Accurate positioning of instruments or sound effects in the sound field. Dialog was clear and effortless to listen to for hours.

    So now that I’ve moved I think I’ll pay very close attention to this set of posts and figure on repeating our previous design.

    • June 27, 2016 at 11:05 am

      Thanks, I’ll double check the link and revise it.

  • June 30, 2016 at 3:35 am

    What was your design target RT as a function of frequency and what are your measured results?

    • July 1, 2016 at 12:18 pm

      We will be adjusting the acoustical characteristics from a relatively “dead” room. Lots of absorption so far, and then some diffusion. Sam Berkow, a very well know acoustician, will be coming back to tune in the final sound.


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