Sound Reduction Performance Research Articles

Trends for prediction methods of heavyweight floor impact sound

Trends of building structures of Japanese multifamily dwellings and prediction methods of heavyweight floor impact sound are introduced. Floor impact sound-reduction performance caused by human action like stepping and jumping is considered to be a vital function for Japanese apartment complexes. There are quite a few cases where the floor thickness shall be designed from 200 to 300 mm because of acoustical performance, to assure the required performance. The practical prediction method, the so-called impedance method, was been established in the 1970s, and it has been commonly used. Though there are many buildings that are out of the applicable scope of the ordinal impedance method with the rise of structural design technology, the outline shown is that of the revised practical prediction method that is under discussion by the working group of the Architectural Institute of Japan. And, examples of hybrid method are also introduced that substitute the impedances by numerical vibration calculation results using finite-element method for simplified calculation results of impedance method.

H-4 音響的ソフト境界を有するダクト消音器の実用化研究 : 試作モデルの消音性能

H-4 音響的ソフト境界を有するダクト消音器の実用化研究 : 試作モデルの消音性能

Condominium noise issues: Problem solving with flooring systems and solving flooring system problems

With increasing frequency, condominiums are being designed without suspended ceilings. At the same time, the popularity of hard floor coverings such as tile continues to grow. These factors combine to create significant problems with impact noise in these buildings. Architects and acoustical engineers have looked to the flooring industry for noise-reduction solutions, and the response has been the production of a wide variety of sound-reducing systems. However, not all of these impact insulation sound reduction systems are acceptable for hard-surface flooring. The total performance of the floor/ceiling system including acoustical as well as durability tests should always be carefully scrutinized, evaluated, and verified by acoustical consultants. Furthermore, strict adherence to proper installation techniques by contractors is essential to achieving the sound reduction performance that should be expected of a given product. Among the major topic areas addressed in this paper are the current flooring industry standards for underlayment systems; realistic expectations for sound reduction and durability from various types of flooring and underlayment systems; and recommended changes in architectural specifications for flooring. This paper also includes practical guidelines for evaluating and verifying the claims made for flooring systems regarding impact sound reduction and several problem-solving examples from real-world applications.

ACOUSTIC UNDERLAY MANUFACTURED FROM CARPET TILE WASTES

Abstract Carpet waste has successfully been converted into acoustic underlay materials that compete with commercial counterparts both in terms of performance and costs. This paper builds on an earlier paper [Miraftab et al, Autex Res.J.5(2), 96-105 (2005).] where granular/fibre mixing ratios, binder concentration and particle size distribution were shown to play a major role in maximising impact sound insulation capabilities of developed underlays. Product optimisation with respect to the particle size as governed by the aperture dimension and mean effective fibre length is further explored in this paper, and the developed underlay is compared with a selection of commercially available acoustic underlays. The results show that a 2mm-aperture screen at the granulating chamber output yields a waste stream with grains in the size range of 0.5-1.0mm and a mean effective fibre length of 2.75 mm which was most suitable to work with, and gave rise to samples with the best impact sound reduction performance. The optimised sample of 10mm recycled underlay (U2) appeared to perform better than most commercial systems tested. The manufactured underlay withstood, and in some instances, outperformed, during the standard tests as required within the BS 5808 protocol. The study concludes that recycling carpet waste to produce quality acoustic underlay with desirable impact sound insulation characteristics is technically feasible, and a viable alternative to landfill or incineration.