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Kinetics Noise Control – High Tones:A True Quadratic Residue Diffuser
High Tones from Kinetics Noise Control is a true Quadratic Residue Diffuser (QRD).While a published comparison between High Tones and another QRD described howHigh Tones varies from theory1, these evaluations were performed on a prototypeversion of High Tones and are not reflective of the current version of the product.
The QRD was invented by Dr. Manfred Schroedor in the 1970’s2. He found that a seriesof wells based on a quadratic residue numerical sequence diffused sound in apredictable manner. A few books have described the methodology for designingQRDs3,4.
High Tones was based on the quadratic residue sequence of {0,1,4,2,2,4,1} created withthe prime number of 7. To create this quadratic residue sequence, High Tones wasdesigned with well depths of 0”, 3/16”, 3/4”, 3/8”, 3/8”, 3/4”, and 3/16” that are separatedby 3/16” wide fins. The 0” deep well was split between each side of the High Tones tocreate a symmetrical pattern. The 0” deep well was separated from the 3/16” deep wellby 3/16” to maintain a constant fin width between wells. These dimensions can beverified on our production version of our High Tones and from the High Tones submittaldrawing, shown below. The drawing is also available on-line at KineticsNoise.com.
To confirm the design, Kinetics Noise Control used independent third-party labs tomeasure the scattering of our High Tones by the International Standard Organization(ISO) international standard method5, and the diffusion by an Audio Engineering Society(AES) informational document method6. These reports are attached. These twomethods measure the non-specular reflections from an acoustical device in very differentways.
The AES informational document method uses an acoustical goniometer to measure thereflection of sound from a small test sample at discrete angles of incidence andreflection. This method will determine the acoustical diffusion coefficients of a sample.Diffusion is defined as how evenly sound is reflected over all angles from a surface. The
Kinetics Noise Control – High Tones: 2 of 2A True Quadratic Residue Diffuser
Kinetics Noise Control, Inc. 6300 Irelan Place Dublin, OH 43017-0655Telephone 614-889-0480 FAX 614-889-0540 Email [email protected] www.KineticsNoise.com
more uniform the reflected sound, the higher the diffusion coefficients. The mainadvantage of this method is that it shows how evenly sound is being reflected off asurface. The disadvantages of this method are that it typically only measures a smallsample size, does not account for the acoustical absorption of the sample, and theresults are not used in commonly available acoustic room modeling packages.
The ISO international standard method uses a rotating turntable and a large samplearea to measure the average sound energy absorbed and reflected in a specularmanner. This method will determine the scattering coefficients of the sample.Scattering is defined as how much (or little) sound is reflected in a specular matter. Theless sound reflected in a specular manner the higher the scattering coefficient. Theadvantages of this method are that it uses a large sample to more accurately representinstalled field conditions, takes into account acoustical absorption of the sample, andthe results are used in all commonly available acoustics room modeling packages. Theonly disadvantage is that is does not determine how evenly sound energy is beingreflected off a surface.
As the reader can clearly see from the attached reports, Kinetics Noise Control HighTones produces significant scattering in the 4000Hz 1/3rd octave band, and significantdiffusion above the 2500 Hz 1/3rd octave band. Thus proving it’s effectiveness as a QRDdiffuser.
Finally, it should be noted that Kinetics used third party labs to measure the response ofHigh Tones with both the ISO international standard method and the AES informationaldocument method, the manufacturer who wrote the now outdated comparison1 only teststo the AES method which they perform in-house.
References:1 D’Antonio, P. “Evaluation of the Kinetics High Tones Diffuser”. [Online] December 15,2007, URL<http://www.rpginc.com/products/flutterfree/KHTD_FF_FF_T_Comparison.pdf>
2 Schroeder, M., “Number Theory in Science and Communication: With Applications inCryptography, Physics, Digital Information, Computing, and Self-Similarity” 3rd ed.,Springer (1997)
3 Cox, T. & D’Antonio, P, “Acoustic Absorbers and Diffusers: Theory, Design andApplication” Spon Press, New York (2004)
4 Egan, M. D., “Architectural Acoustics” McGraw-Hill, Inc, New York (1988)
5 ISO 17497-1, “Acoustics -- Sound-scattering properties of surfaces -- Part 1:Measurement of the random-incidence scattering coefficient in a reverberation room”
6 AES-4id-200 “AES information document for room acoustics and sound reinforcementsystems -- Characterization and measurement of surface scattering uniformity”
NWAA Labs 25132 Rye Canyon Loop, Santa Clarita, CA 91355, Phone: (253) 973-1018
Email address…[email protected]
RANDOM- INCIDENCE SCATTERING COEFFICIENT TEST REPORT No. NW071807-1
Client: Kinetics Noise Control 6300 Irelan Place
Dublin, OH 43017-0655
Test Date: 18 July 2007 Test Specimen: Wooden Linear Diffuser INTRODUCTION The methods and procedures used in this test conform to the provisions and requirements of ISO Procedure 17497-1, Acoustics-Sound-scattering Properties of Surfaces, Part 1, “Measurement of Random-incidence Scattering Coefficient in a Reverberation Room”. Copies of the test standard are available at www.iso.org. The test chamber is a cuboid, 871.7cm long by 541cm wide by 609.6cm high, and volume is 275 cubic meters. There are six fixed surfaces and two movable/fixed surfaces oriented as diffusers in the reverberation room. There are two sources one in each corner consisting of two Dodecahedron speakers and two sub-bass cabinets for extended low frequency capabilities. We utilize 3 Earthworks M-30 Omni directional microphones to gather the impulse responses. This test report relates only to the item(s) tested. Any advertisement that utilizes this test report or test data must not imply product certification or endorsement by NWAA Labs. DESCRIPTION OF TEST SPECIMEN The test specimen consisted of wooden cut planks arranged in a circle with a diameter of 10.75 ft. The test specimen consisted of 33 planks, each of which was 4 inches wide by various lengths with linear extrusions. The samples had a solid core so it was not necessary to back fill the edge areas. The planks were arranged so the pattern was linear. The shape of the sample was circular and had a nominal diameter of 10.75 Ft. The pattern is shown in the included photo. Test Results are presented on the following page. Submitted by, NWAA Labs Inc ___________________________ Ron Sauro NWAA Labs Inc
Sample Name:
Time Temperature (in C°) Humidity
Start 6:37 24.82Running 24.83 Running 49.8%
Stop 6:54 24.84 50.0%
Time Temperature (in C°) Humidity
Start 5:20 24.86Running 24.86 Running 51.3%
Stop 5:38 24.86 51.0%
Time Temperature (in C°) Humidity
Start 6:12 24.65 49.0%Running 24.71 Running 49.3%
Stop 6:30 24.77
Time Temperature (in C°) Humidity
Start 4:50 24.85 52.0%Running 24.86 Running 51.8%
Stop 5:10 24.86
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Kinetics High TonesTemp and Humidty Worksheet
T-1
NWAA Labs25132 Rye Canyon LoopSanta Clarita, CA 91355
(253)-973-1018
Sample: Kinetics High Tones
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100Hz 0.02 0.01125Hz 0.00 0.00160Hz 0.07 0.00200Hz 0.00 0.00250Hz 0.00 0.00315Hz 0.00 0.00400Hz 0.03 0.01 NRC 0.03500Hz 0.07 0.00630Hz 0.11 0.03 SAA 0.04800Hz 0.08 0.011000Hz 0.02 0.021250Hz 0.01 0.041600Hz 0.02 0.012000Hz 0.05 0.072500Hz 0.09 0.053150Hz 0.07 0.134000Hz 0.12 0.435000Hz 0.14 0.496300Hz 0.10 0.278000Hz 0.09 0.37
10000Hz 0.03 0.26
NWAA Labs25132 Rye Canyon LoopSanta Clarita, CA 91355
(253)-973-1018
Kinetics High Tones
