• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.252-256
• /
• 2001

Scattering of surface materials has been known as one of the most important aspects in evaluating the acoustics of concert halls are designed. One of the methods that can reduce the errors in estimating the reverberation time and other acoustic parameters through computer modeling is to calculate scattering coefficient of surface materials. However. so far, no objective and reliable methods measuring scattering coefficient has been suggested. In this situation, ISO has suggested the method of measuring the random-incidence scattering coefficient on surfaces in diffuse field, whereas AES has introduced a method on directional-incidence in free field. In this study, the scattering coefficients of five kinds of hemispheres (1.5, 2.0. 2.5. 3.0. 3.5cm) were measured by using the ISO method in 1：10 reverberation chamber. It was found that 3.0cm hemisphere has the highest scattering coefficient satisfying 95％ reliability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.29-32
• /
• 2008

In this study, acoustic diffusers were designed as to the ISO method, which measured the random-incidence scattering coefficient of surfaces in a diffuse field. The diffusers which were made of GFRG (Glass Fiber Reinforced Gypsum), consisted of the cubes with different height and width. The height was from 50 to 250 mm and the maximum height was at the center of the diffusers to provide the early reflections. The surfaces were irregularly designed in order to add the lateral reflections. The scattering coefficient of the diffusers was measured in a 1;10 reverberation chamber, but the absorption coefficient was measured in a real scale reverberation chamber. The result of the scattering coefficient was compared to the hemisphere diffusers and the absorption coefficient was compared to ISO 354 data. To validate the measurement results, the scattering coefficient of the diffusers will be measured in a real scale reverberation chamber.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.983-986
• /
• 2007

The absorption power of a surface depends on the surface irregularity which has been known as an important factor in determining scattering coefficient. This study investigates the effect of increase in surface area on the absorption and scattering coefficients of a diffuse surface. The surface irregularity or surface pattern can be compared to the wavelengths and the random-incidence scattering coefficient of surface is measured by ISO 17497-1. The scattering coefficients of increasing the surface area in linear pattern of v-cut groove on rubber plate were measured in 1:10 scale model reverberation chamber. It is found that the scattering and absorption coefficients increase with increasing surface area. At 60% of increased surface area the spacing between the hemisphere diffuser and the v-cut groove acts similar with results of absorption coefficient. The results show that absorption coefficient depends on surface area and the spacing where as scattering coefficient depends on surface area and texture.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.3
• /
• pp.162-168
• /
• 2003

The degree of diffusion, characterized by the "scattering coefficient" of surface materials, has been known to be one of the most important factors in determining the acoustical qualities of concert halls. Based on the suggested ISO method, which measures the random-incidence scattering coefficient of surfaces in a diffuse field, the scattering coefficients of different sizes and densities of wooden hemispheres and cubes were measured in model-scale reverberation rooms. As a result, wooden hemispheres with a structural depth of more than 15㎝ have the highest average (500㎐∼4㎑) scattering coefficient. It was also found that the scattering coefficient becomes higher when the diffuser density reaches about 50% for hemispheres and 30% for cubes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.979-982
• /
• 2007

The effect of a scattering wall surfaces on sound diffusion can be assessed by determining the scattering and diffusion coefficients in the laboratory. However, the sound field in a concert hall including scattered reflections is different from the laboratory measurement condition. Therefore, there is a need for objective investigation of diffusion in real sound fields. In this paper, possible acoustical parameters of in-situ measurements are discussed.