Auralex Acoustics Room Analysis Kit

Auralex Acoustics Room Analysis Kit
by Barry Rudolph<

The Auralex Acoustics Room Analysis Kit provides all the tools needed to acoustically analyze any listening space without knowledge of acoustics, electronics or monitor speaker setup. Essentially this is a way to get a professionally trained acoustician's assessment of the sonic characteristics of your studio control room, rehearsal space, home theatre or live venue at a fraction of the cost of an on-site acoustics specialist.

Key to this process will be Auralex's expert guidance on the resolution of your room's acoustical problems through the recommendation of the installation of their products. New construction (remodeling) might be advised where superior results are demanded from rooms with extreme problems.

Auralex's in-store retail Room Analysis Kit is based on the company's existing on-site professional Room Analysis Plus Program. More is at information at www.auralexelite.com/resource_center/room_analysis.asp.

The $499 Auralex Acoustics Room Analysis Kit was created based upon the need for a more thorough, in-depth diagnosis of room problems. By using this especially designed field kit, the precise capture and recording of empirical acoustical datum is more tightly controlled resulting in an accurate "picture" of your room's sonic characteristics.

It is important to stress that while there are working electronic room correction systems available that attempt to analyze a room's response in the frequency and phase domains and then apply a corrective inverse filter, it is impossible to correct room problems electronically in the time domain.

Resonant room modes (or nodes) caused by sound waves interacting between sidewalls (tangential), floor to ceiling (axial), or from the front to back (longitudinal) are only ameliorated by placing effective acoustic materials in certain proscribed locations on wall and ceilings.

I own a KRK Ergo Room Correction System but, first of all, I wanted to get my space acoustically "together" as close as possible using acoustical treatments. The KRK Ergo's filters will then work more accurately and with less concomitant processing artifacts in an acoustically-corrected room.

The Auralex Acoustics Room Analysis Kit

The kit comes with an omni-directional measurement microphone, a USB thumb drive with 20Hz to 25kHz swept sine signals (in .aif format) at a variety of sample rates up to 96kHz plus both a complete instructional guide and room analysis questionnaires for three types of listening spaces.

The standard form for production spaces and studios is at: www.auralexelite.com/resources/pcf.pdf

The home theatre/residential form is at: www.auralexelite.com/resources/HTRAF.pdf

The large room analysis form is at: www.auralexelite.com/resources/LRAF.pdf

Analyze This!

The Response Curves Before Acoustical Treatment

This graph shows the low frequency area in need of correction.

The response up to 1kHz

This is an overview of the response from 30Hz to 10kHz

This detailed questionnaire about your listening space requires information such as: the height/width/length room measurement, the distance to and from all walls to the exact position of the monitor loudspeakers, the listening position, walls and ceiling construction materials, existing room treatments, type(s) of monitor loudspeakers, budget allotment for room treatments, kinds of (genres) of music produced in your room, and the exact nature of the acoustical problems you're experiencing.

An additional piece of graph paper (.pdf) is provided for drawing out a floor plan of your room. You should include architectural details such as exposed ceiling joists, windows, drapes, and doors--anything that would affect the room's response. Auralex encourages taking and sending pictures of your space so their engineers can see exactly what they are up against.

It's very simple. I used my RTZ Professional 9782 microphone pre-amp for the phantom-powered measurement mic that came with the kit. Auralex recommends a solid-state mic pre-amp as oppose to a tube pre that might "color" the frequency response of your analysis recording. Use the flattest and most neutral sounding pre-amp you can get.

To "ping" your room you must be able to play the sweep tone and record it playing out of your left monitor speaker at the same time. This is no problem for any DAW program and once you've done that, simply render the digital audio as an .aif format. I played the tone at a loud level and wore earplugs. The sweep tone starts so low that my main monitors didn't even reproduce it.

My Crude Drawning Of My Room Plan

I e-mailed the recorded file and questionnaire (or you can send everything in the mail) directly to Auralex's acoustical engineers to analyze.

Frequency response, impulse response, waterfall plots and reverberation time (RT) values were generated and a written report returned within five to seven business days outlining the acoustical issues and the recommended acoustical treatments that will solve them.

The engineers at Auralex took on my studio as a special challenge and as a great test of the Room Analysis Kit for two main reasons. Firstly, my Pro Tools mixing space is a three-wall alcove--with no back wall behind the listening position--it opens up to my living room. Secondly, it is a small, 10 X 10 X 10 foot box I've already loaded with Auralex products on the ceiling and walls.

As anybody who has mix music in a small space will tell you, the main sound issue is low frequency response irregularities--buildup and cancellation caused by peaks and dips at certain frequencies.

Years ago when I first set up Tones 4 $ Studios, the sound was glorious coming from my Adams 2.5A monitors--even my Yamaha NS10m monitors sounded fat.

Of course that's the problem: outside of my room, my mixes sounded thin because, while mixing, I was hearing so much low end and excessive level in the 300 to 500Hz region, I would instinctively roll it out of nearly everything. Outside on any system, vocals and guitars were thin sounding and overly mid-rangy and as for the drums and bass, people complained: "where's the beef?"

Tones 4 $ Studios

Move Mouse Over Any Image To Pause--iPad and Smart Phone Users Can Refresh--

Auralex To The Rescue Before Analysis

Installed Recommended Ceiling Treatments

I frantically started installing bass trapping in the corners and at the boundary between the front wall and the ceiling using many Auralex LENRDS. Much to the chagrin of the engineers at Auralex, I also mounted Great Gramma panels (with foam side out) across and spanning each corner at the monitor's height. I also stuffed a LENRD behind them too.

My room finishes with six, 2 X 4-foot Auralex ProPanels---absorption panels on the walls and six SpaceArray Difusors on the ceiling directly above the mixing position. The two sidewalls each have panels of heavy Velour drapes and the entire space is carpeted.

This greatly improved my situation but it was not as good as I wanted. I measured my room following the directions and sent in the questionnaire and audio files. Soon a written assessment of the main problems came along with a graphical frequency response with 1/24th octave smoothing.

Auralex supplied this waterfall graph that shows the relationship of frequency, energy and time in my Tones 4 $ Studios.

Auralex Recommendations

Armed with this information and his experience, acoustician. Andy Teipen recommended adding six more LENRD bass traps to the sidewalls' horizontal corners (where the ceiling and side walls meet) to deal with the peak in the 85-100 Hertz range. There is a tangential mode at approximately 99 Hz causing this problem.

He also told me to remount all the ProPanels on the walls so that they stand off 3-4-inches off of the wall surfaces thus creating an air space between the panel and the wall. This would help with overall low frequency absorption and in particular, the side-to-side axial mode problems in the room. However, so far I have not done this step but I will soon and then I'll re-ping and update this report.

There is a floor to ceiling axial mode at approximately 80.7 Hz, which is contributing to a dip in that frequency range. The existing SpaceArray panels I have on the ceiling should be dropped down 3 to 6-inches and the gap behind them filled with Auralex EcoTech panels.

It was also suggested that I add a thick, dense curtain to "close off" the studio from the living area. It would definitely improve things, but it is not domestically feasible.

The Auralex "After" Picture

The large, four-color graph below shows the before and after curves plus the curves with the Ergo system working. I did a separate ping with Ergo running, as the Auralex engineers were interested in those results too.

The Response Curves Showing Before And After And With And Without The KRK System Running.

Auralex Comments
With the addition of acoustical treatments, significant improvement is seen in the 70-125Hz, 200-300Hz and 500-600Hz regions.
In particular the cancellation at 99Hz is improved by 10dB while cancellation in the 500-600Hz range is improved by 7dB.
The response in the 200-300Hz range improved from +/-5dB to +/-0.5dB
The flat response from 200-300Hz is phenomenal and the KRK Ergo System brings this range closer to the "average SPL"
Before treatment there was a difference of 24dB from the lowest dip to the highest peak across the spectrum.
After treatment, this was reduced by 17dB.
The response of the room was vastly improved after treatment was installed and the KRK Ergo System was utilized.

"Average SPL" refers to the -12dB line on the graphs. All observations are referring to the graphs with 1/24-octave smoothing.

Proof Is In The Mix

With my room treated now I find getting sounds and developing mixes to go much smoother. Standard mix processes like equalizing and compressing are much more hearable and defined while doing them. I also notice an immediate improvement of stereo imaging--in particular, I hear a stronger center image. I have no bass issues at all--whatever kind of low frequency "foundation" I'd like to build is possible and, as I expect, it comes without uncertainty or ambiguity as to its "size". In addition, I can work at whatever level I desire without worry of bass hype due to loud monitoring volumes. The best thing of all is that the mix holds up well and translates perfectly outside of my studio.

I had to go back and listened to those early (before Auralex treatment), old mixes that my clients complained about and, guess what? They were right! I had wrongly equalized vocals and guitars (and most other mid-range instruments) because I was hearing the 200 to 500Hz frequency range of those sources out of true proportion.

The biggest change to the sound of my room came from adding Auralex Acoustical treatments--even my earlier, primitive attempts by putting up different Auralex products worked somewhat. The key was hiring a professional by proxy--using the Auralex Acoustics Room Analysis Kit and following Auralex's recommendations.

Other Services

Auralex also offers Room Analysis Pro, an on-site analysis of room acoustics and sound quality conducted by any of Auralex's lead acoustical engineers. They will work directly with the dealer to coordinate the project details, create a quote based on job scope and site location, and schedule the actual on-site visit. Acoustical measurements will be taken and then analyzed in order to create an acoustical analysis report within five to seven business days of the on-site visit.

The cost of the Room Analysis Pro service is quoted on a per project basis. Most projects will fall into the range of $1,500-2,000 per day plus expenses. The per-day fee calculates how many days the engineer is physically away from the office for a particular project. Most projects will only involve one day of testing, while in some cases an additional day may be needed for long-distance travel.

Visit the Auralex Web site at www.auralex.com.

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