the paper presents the results of an investigation on the acoustic performance of vertical profile parallel barriers with quadratic residue diffuser tops and faces. a 2d boundary element method (bem) is used to predict the barrier insertion loss. the results of rigid and with absorptive coverage are also calculated for comparisons. using qrd on the top surface and faces of all vertical profile ...

the paper describes an investigation about the application of the new multiple-impedance discontinuities model for optimizing profile diffuser barriers. the new multiple-impedance discontinuities model is much faster than the numerical method, thus it is used in an optimization process. the a-weighted insertion loss was used for the traffic noise spectrum. the result of optimization, which is d...

Room acoustic diffusers can be used to treat the acoustics of critical listening environments to improve speech intelligibility and to make music sound better. The development of the modern sound diffuser can be traced back to the pioneering work of Schroeder, who developed the phase grating diffuser. These consist of a series of wells of different depths separated by fins. The order of the wel...

We find that the minimum distance of the binary [137; 69] quadratic residue code is 21.

A previous paper [Applied Acoustics 66, pp.709-730, 2005] has shown that adding a quadratic residue diffuser (QRD) to the top of a T-shape barrier can provide better barrier performance than an equivalent purely absorptive barrier. In here, we extend the study to look at the performance when a QRD is made absorptive. This paper presents an investigation on the acoustic performance of a few well...