QRD734™ 

Quadratic Root Diffusor

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Acoustic Data - Diffusion Coefficient
At the moment there are two working groups involved in establishing methods to measure and characterize scattering surfaces. The AES Working Group SC-04-02, chaired by Dr. Peter D'Antonio and vice-chair Dr. Trevor Cox, is proposing a method to determine the uniform diffusion coefficient. This coefficient, which is bound between zero and one, is derived from the circular autocorrelation of the 1/3-octave angular responses. The diffusion coefficient can be used to evaluate potential diffusing surfaces

Diffusion Coefficient
Hz	QRD® 734	Reflector
125	0.71	0.67
160	0.71	0.66
200	0.73	0.68
250	0.73	0.70
315	0.64	0.70
400	0.77	0.68
500	0.88	0.70
625	0.83	0.68
800	0.81	0.64
1000	0.80	0.59
1250	0.70	0.47
1600	0.69	0.42
2000	0.69	0.42
2500	0.68	0.41
3150	0.62	0.35
4000	0.56	0.31

 
RPG is a member of the Working Group ISO/TC 43/SC 2/WG 25, chaired by Dr. Jens Rindel, to study a method to evaluate the random incidence scattering coefficient, used in computer modeling programs. The ISO 17497-1 standard has been recently published and work continues. The scattering coefficient is obtained by a comparison of the reverberation times, obtained from phase-locked average integrated impulse responses, for a stationary and rotating sample in a reverberation chamber.

Scattering Coefficients

Scattering Coefficient
Hz
125	0.06	0.00
162.5	0.04	0.04
200	0.16	0.11
250	0.15	0.06
312.5	0.39	0.18
400	0.42	0.26
500	0.45	0.21
625	0.68	0.21
787.5	0.91	0.22
1000	0.95	0.21
1250	0.83	0.22
1562.5	0.99	0.23
2000	0.88	0.16
2500	0.89	0.21
3125	1.06	0.24
4000	0.91	0.39