1. Auralex Acoustics. “The Importance of Placement of Auralex® Acoustical Products.” YouTube video, 6:50. Posted June 8, 2010. Accessed November 10, 2014. http://www.youtube.com/watch?v=I3q5kQjMAbc.
Terry, an employee of Auralex Acoustics, walks the viewer through the first steps of treating a room. If you have never attempted to acoustically treat a room, this YouTube video is a great place to start. I honestly think that this demonstration is a little basic, but many first-timers will find the video useful. The materials used are Studiofoam Wedges, LENRD Bass Traps and T’Fusor Sound Diffusors. Terry suggests mostly covering the back wall where the mixing position is fixed. The “mirror trick” is discussed as a basic means of treating reflections. Bass traps are covered in all four corners of the room and an array of diffusors are placed in an alternating patterns to increase the randomness of scattering of sound waves. A major flaw in their demonstration is the lack of sound comparisons. They chose to show before-and- after photos. While that may be fine, the video really does not leave the listener aurally satisfied.
Bartlett, Bruce, and Jenny Bartlett. “Sound, Signals, and Studio Acoustics.” In Practical Recording Techniques: The Step-By-Step Approach to Professional Audio Recording. 5th ed. 27-32. Burlington, MA: Focal Press, 2009.
In the Bartletts’ book, they cover mostly recording techniques. However, they do cover a small section of the book about acoustics under the heading “Controlling Room Problems with Acoustic Treatments.” It is essential to know when one needs to acoustically treat a room, so they list several instances that would cause the need for treatment. They discuss different types of treatment that treat certain frequency bands. For example, a bumpy foam mattress from the store can treat some high frequencies. They suggest different thicknesses for other frequency bands. A diagram showing an ideal acoustic treatment setup is included. Because there are audiophiles that cannot afford legitimate treatment products, the Bartletts give examples of cheaper alternatives, including sleeping bags. They discuss many ways to absorb bass frequencies on a budget because bass frequencies are the hardest to treat in a room.
Bregitzer, Lorne. “Creating a Great Recording from the Start.” In Secrets of Recording: Professional Tips, Tools & Techniques, 3-4. Burlington, MA: Focal Press, 2009.
It is crucial that, when recording, the acoustic space be absorbed. Bregitzer discusses the basics in the heading “Acoustic Treatment of the Control Room.” He advises wood as a great alternative to the more expensive treatments; wood is a semi reflective surface that also retains a neutral environment. He also recommends when to use a dead space as opposed to a slightly reverbed space. Tiled surfaces, that cause some reverberation, can be beneficial when recording drums, but it is not recommended when recording vocals. For vocals, it is okay to have a completely dead room to record. This source is useful for “portable” musicians that need to transport equipment. Bregitzer shows us a figure of a portable gobo that isolates specific instruments in a room. These prevent extraneous room noise from being captured by the microphone.

2. Ciletti, Eddie. “Acoustics on a Limited Budget.” Mix 26, no. 7 (June 2002): 138-143.
As the title suggests, this source is useful for those not seeking the high-tech acoustic treatment for their studio. Ciletti teaches us about monitor placement within a room; the setup should be symmetrical and many producers fail to do that. He suggests drawing a setup plan and indicating positions of many things to make the process easier. Most of the acoustical detail can be obtained by hand clapping, and that is one the best ways to go about treating a room. Ciletti provides suggestions on monitor placement and absorption. He covers the reflective qualities of certain materials and what to use to tame certain frequencies. A table depicting reverberation times of certain frequencies in a specific room is shown. He lists the dimensions of the room and many additional details. As far as treatment is concerned, the Type 703 Rigid Fiberglass insulation is recommended. This treatment comes in many thicknesses and it is very dense. Other dense treatments can treat low frequencies because absorption of low frequencies require more mass.
Clark, Rick. “Studio Design, Room Tuning, and Wiring.” In Mixing, Recording, and Producing Techniques of the Pros. 2nd ed. 283-298. Boston, MA: Course Technology PTR, 2011.
In this informative chapter on acoustics and design, Clark provides interviews with numerous leaders in the music industry, including George Augspurger, Bob Hoda, Bret Thoeny, Chris Huston, Cookie Marenco and Michael Rhodes. Augspurger warns producers of electrically equalizing a room as a substitute to acoustic treatment. Doing so can produce a bad mix. Hodas discusses his thoughts on how to fix things acoustically when he walks into a room. He discusses bass trapping in addition to diffusers. Thoeny emphasizes different brands of studio monitors, Huston differentiates between acoustics in home listening rooms and studio control rooms, Mareno discusses patch bays and wiring and Rhodes informs us on studio design and planning. It’s a great source for those seeking opinions of leaders in room tuning and studio design.
Cox, Trevor, and Peter D'Antonio. Acoustic Absorbers and Diffusers: Theory, Design and Application. 2nd ed. London: Taylor & Francis, 2009.
Any producer can find himself departing the mixing position and walking around the room only to find out that the mix sounds “funny” and unbalanced in certain areas. In such a case, the room is considered to be non-diffuse. Most producers will understand acoustic treatment panels and its use for absorbing sound waves and redirecting those waves in other directions away from the producer’s ears, but the word diffusion seems to confuse many. The authors dedicate a chapter on absorbers and a chapter on diffusers. They provide suggestions on how to calculate different reverberation times and solving echo problems in a room. It is crucial to keep in mind that reverberation and echo are two different things. Throughout most of the book, the authors discuss measurements of absorber properties and diffusion, restrictions of porous absorbers and uses of resonance absorbers, formulas used to predict the scattering of sound, and various shapes of absorbers and diffusers. They accentuate the quadratic residue diffusers (also known as the Schroeder diffuser) and primitive root diffusers as an alternative. Because this book provides many case studies and illustrations of installations, it is great for acousticians seeking an in-depth technical approach of the two treatments. It is also a great tool for producers seeking to redesign and experiment with acoustics in their studio. The first edition is reviewed in brief by Manfred Schroeder in Journal of the Acoustical Society of America 117, no. 6 (June 2005): 3343.

3. Everest, Frederick, and Ken C. Pohlmann. The Master Handbook of Acoustics. 5th ed. New York: McGraw- Hill, 2009.
Considered a best-selling book on acoustics for over twenty years, this handbook delivers all aspects of acoustics to a group studying in the field. Pohlmann stresses the importance of acoustics because it has transformed cultures and lives of people. Sound is an involuntary natural phenomenon that simply none of us can escape; try to imagine a world without it. Pohlmann discusses many topics including the fundamentals of sound, reflection, diffraction, refraction, diffusion, comb-filter effects, reverberation, absorption, modal resonances, controlling of noise, and the acoustics of various environments ranging from small home and recording studios to large halls. The author also presents many acoustical problems that arise in any recording environment when mixing audio and techniques that can be exercised to ensure optimal and accurate acoustics in these rooms. This book is an essential tool for the average person seeking a more pleasurable listening experience, but it’s a must-read for all levels of producers, including the most seasoned audio mixing and mastering engineers. The first edition is reviewed by Neil A. Shaw in Journal of the Acoustical Society of America 110, no. 4 (October 2001): 1714-1715.
Fett. “Sound Treatment, Then and Now.” Performing Songwriter 13, no. 92 (March 2006): 80-81.
Fett, a record producer and recording engineer based in Nashville, describes his own experience regarding acoustic treatment. He bought a lot of treatment from the company Auralex and applied it to several rooms that he asked to be constructed by a contractor. He spent $1,200 on just 2-inch wedges and he completely covered the room and most of the ceiling. He used this environment for his mixing needs as well as CD projects and demos. It became a disadvantage in the long run because he was missing natural reflections in his mixes. He attended an event and discovered the Studio Traps product. This material was made specifically for placing around microphones as “the early reflections are tuned to exactly the right musical decay time.” His problem was also that he used all absorption but no diffusion. He also discovered the StudioPanel, a material combing absorptive and diffusive qualities. He gained an appreciation when he tested it. Eventually, he decided to convert the room he used for nearly a decade. H applied what he learned to the makeover. He said it sounded natural. Mixes will turn out far better in a live-sounding room than a reflection-free, dead-sound room.
Hanson, Robert. “The Taming of the Room.” Mix 31, no. 6 (June 2007): 34-40.
In Hanson’s article, he reviews talks from five distinguished studio designers. They include George Hallowell, Chris Pelonis, Richard Schrag, Larry Swist and Carl Yanchar. Each discusses common errors when treating project studios, speaker placement issues, acoustic treatment placement issues and suggestions regarding the best-case scenario in any given room. Hanson includes a table of nineteen manufactures of acoustic treatment and their products and website information. Most of the article is based on talks by the studio designers, but Hanson provides tips for the D.I.Y. people in its own section. Swist narrows the process in four steps, including elimination noise intrusion (noise propagated by air conditioners, computers, etc.), creating a wide-bandwidth absorptive surface behind the monitoring position (or the front of the room), creating a more diffuse back wall (increasing the randomness of the scattering of waves) and treating the ceiling with absorbing material. Swist explains each tip in greater depth if you are looking to do things yourself.

4. Harvey, Steve. “Treatments for Small Space Acoustics.” Pro Sound News 35, no. 5 (May 2013): 1-30.
I should point out the article is roughly a page in length, not thirty. It starts on the first and is continued on the thirtieth. He jumps into the article by quoting Ethan Winer on the importance of bass trapping and avoiding reflections. He also refers to Winer’s book titled The Audio Expert. To give an idea of what special acoustic treatments look like when applied correctly, Harvey includes a photo of a mastering studio near Raleigh, North Carolina. One may notice that a particular room does not have to completely covered in treatment; the listening space may (or should I say, will) become unnaturally anechoic. The topic mainly covers four problems that should be considered; modal problems, speaker- boundary interference, comb filtering, and poor diffusion. Of course Harvey explains what to listen for and how to fix these problems in brief. If your mixing room has any kind of windows, then consider a specific acoustic treatment mentioned near the end of the article. Treating a room is easier said than done; it’s really not that easy. Harvey even says that “tuning in our rooms is moving things fractions of an inch.”
Heinze, Carolyn. “Special Treatment.” Electronic Musician 21, no. 5 (May 2005): 39-49.
A problem when mixing a project is that it will sound great in the studio but it will sound unpleasant on other playback systems. The problem is the room is not acoustically treated properly. It is likely not treated because of financial hardship (we’ve all been there), but you can successfully treat a room without breaking the bank. Heinze stresses the importance of analyzing, and investing in, the acoustics first before doing anything else. Most producers will go for the monitors first. She suggests treating low frequencies first. Examples of inexpensive remedies mentioned are sheet-rock and Plexiglass (to put over windows). Other materials high in mass will also work. She mentions software like Room Sizer and Room Optimizer. This allows the producer to analyze a room and model the space before buying what they need for the room. As far as spending, Heinze suggests a half-and-half split between acoustic treatment and recording equipment. The average dollar amount for a nice acoustically treated room is set at $1,000 and for true audiophiles that dollar amount ranges between $1,500 and $2,000. She also presents ways to treat a room with just $500.
Izhaki, Roey. “Monitoring.” In Mixing Audio: Concepts, Practices and Tools. 2nd ed. 80-85. Burlington, MA: Focal Press, 2013.
Izhaki only covers a small section on acoustics and the relevant aspects in small project studios. He states a common problem regarding going about treating a room; that is, standing waves. Standing waves occur when a frequency is amplified or attenuated within a room. These happen because that frequency’s wavelength is that of the parallel walls it is bouncing off. In other words, the wave remains in a constant position. He presents a formula on calculating resonant frequencies (room modes). If left untreated, mixing will suffer, so he demonstrates many options of acoustically treating these room modes. It all comes down to diffusion and absorption once again. Flutter echoes and early reflections are also common problems that Izhaki addresses in brief.

5. Kleiner, Mendel, and Jiri Tichy. Acoustics of Small Rooms. Boca Raton, FL: CRC Press, 2014.
Today many musicians utilize their own living space to create music. They may dedicate a room in a house, such as a bedroom, as their control room and mixing space. Chances are that the room is not big and does not exceed a few hundred cubic meters. Because acoustic behavior is substantially different in small spaces than large, a producer on a tight budget may not need expensive equipment to optimize the space. It would be unnecessary. The book discusses many concepts, starting with the basics in the first few chapters. They discuss sound absorption and diffusion in separate chapters. Because studio monitors interact with the room as well, the authors discuss its properties. Models of room acoustics and descriptions of room-measuring devices conclude the book.
Leone, Fabio. “Acoustic Panels Effect: Cheap Room Treatment.” YouTube video, 2:33. Posted October 2, 2011. Accessed November 19, 2014. https://www.youtube.com/watch?v=cp56A6TcL1E&list=UUQ3o6g_cliC2Odhk_M7aCzQ
In Leone’s video, he compares the acoustic behavior of a completely empty room with that of a more properly treated [same] room. He plays a simple rhythm on a snare drum. Notice how long it takes for the acoustical energy of the snare drum hit to decay to nothing at 0:03; it is very shocking. At 0:33, he plays a similar rhythm, but with eight bass traps attached at every corner of the room. Notice how much more quickly it takes for the sound waves to decay to nothing (RT60). More importantly, notice the attenuation of the lower frequencies. A small change makes a big difference. A more dramatic difference in acoustics happens at 1:06. He applies treatment to the ceiling, further decreasing the time it takes for the energy to diminish to nothing. At 1:35 he adds treatment to the walls. There is a more subtle difference in sound quality when compared to the clip at 1:06, but notice the drastic change with just treatment on the ceiling. The video received roughly 247,650 views as of Midnight on November 19, 2014. According to his description of the video, the sound was captured on a Panasonic Lumix DMC-TZ10 digital camera.
McCarthy, Bob. "Acoustics/Room Tuning." Sound & Video Contractor 28, no. 4 (April 2010): 34-39.
In this article, McCarthy discusses three types of acoustical treatment and their unique roles in the studio; they include absorbers, tuned resonators, and diffusers. Throughout the article, he includes close-up photos of the EcoSorpt, Tube Trap, MegaTrap, StratiQuilt, and Art Diffuser acoustical treatments. They are accompanied by a detailed description of the treatments’ acoustic values when applied in the studio, in addition to their dimensions, densities, and maximum noise reduction in decibels. Without accompanying close-ups, he also discusses the Elite ProPanel, Binary Amplitude Diffsorber, and AlphaSorb treatments in brief detail. Although these are all essential in the studio, McCarthy stresses the importance of discovering what one needs before going out and purchasing treatments left and right; one may not need an absorber or diffuser after all. To conclude, he discusses numerous spectral analysis tools that are capable of examining diffuse reflection patterns and reverberation decay timings in a room. Four great analysis systems mentioned are EASERA, 7841 DIRAC, SIM 3, and Smaart 7. This is a great article for true audiophiles seeking a neutralized mixing environment through technical study their room’s acoustic behavior.

6. Senior, Mike. “Using Nearfield Monitors.” In Mixing Secrets for the Small Studio, 16-30. Burlington, MA: Focal Press, 2011.
Many of the acoustical problems are discussed in regards to using near-field monitors in the room because they are the commonly used type. Right away he includes a diagram of a room and arrows indicating directions of sound waves from the speaker and the acoustic treatments. It is also suggestive to avoid completely covering a room with treatment. A term that may not be familiar to some is the boundary effect. He describes it in great detail. There are many producers that seem to neglect room resonances, or room modes, a problem that is hard to tackle. Senior does warn how expensive treating these may be. He suggest playing sine waves of certain frequencies and walking around the room to get a sense of what the room modes are doing to your mixes. He suggests avoiding mixing in rooms with heavy-weight walls; light-weight walls allows more low frequencies to escape the room, further enhancing the mixing experience. If heavy-weight walls are the case, he reviews mineral-fiber bass traps and limp- mass bass traps as practical remedies. He follows up on affordable alternatives of bass trapping if you can’t spend a lot of money.
Winer, Ethan. “Setting Sonic Traps.” Pro Sound News 33, no. 5 (May 2011): 34-36.
Many small mixing spaces are difficult to control because early reflections from close surfaces are more dominant than those from more distant surfaces. As a result, echoes are louder and bass frequencies worsen. Winer gives the reader helpful suggestions on what kind of treatment to use to absorb certain frequency bands, although the article focuses on low frequencies because they are the most difficult to treat. If a producer uses only one kind of broadband treatment (say, 2 inches thick) that treats mid to high frequencies, balance issues will occur and he will hear even louder bass frequencies. As far as bass- trapping is concerned, Winer points out a great absorber, the MegaTrap made by RealTraps. The trap is effective to treat low frequencies down to 40 Hertz. RealTraps also developed the Modular System, a stack of MegaTraps, for those who want their walls unscathed. They are able to be placed in the corners of a room without having to be secured to the wall. Winer concludes the article with another material of the Modular System, the RealTraps Diffusor.
Zhang, Wei. “Simulation and Experimental Study of Room Acoustics.” PhD diss., University of Ottawa, 2006. ProQuest (AAT 304918154).
In Zhang’s thesis, he explores strictly room acoustics and three major components within; the sound source, acoustics of the room, and the listening. When mixing music, it is crucial to understand how low, mid, and high frequencies propagate in an enclosed space. More importantly, the dimensions of the room play a large role in amplifying certain wavelengths or cancelling frequencies (comb filtering) if the room is not properly treated. He informs the reader of sound fundamentals and methods including wave- based, ray-based, ray tracing, image source and physical scale modeling methods. He incorporates computer modeling of different rooms to predict acoustic behaviors in a real-life situation. Following his findings, he discusses his experimental study with room acoustics in a real room using low frequencies. Zhang conveys his thesis in a more scientific approach, but it is applicable to a musician or producer.