Numerical study of sound wave modulation for floor noise mitigation

Abstract

Floor noise inducing constant public complaints as well as serious violent has been an inevitable social phenomenon in an urban area where multi-dwelling housing accounts for the majority because households share a wall and a floor. The multi-dwelling housing is particularly vulnerable to floor impact noise, which is the main source of floor noise, classified into light-weight impact noise and heavy-weight impact noise. Heavy-weight impact noise, which is generally caused by heavy impacts such as a running child and a jumping man, has raised most of the public complaints and has remained unresolvable since the beginning of the issue. In order to achieve reduction of heavy-weight impact noise, fundamental theories necessary for developing a noise modulation concept are examined and verified in a numerical way. Then, with the noise modulation concept, the hard panels with the optimized pattern capable of reducing sound wave energy by refracting and reflecting the sound waves, resulting in mitigation of floor noise, are developed. By the use of a finite element method tool, Ls-dyna, numerical analyses of the hard panel verifying their performance in reduction of floor noise are conducted against four different impact sources, two types of dwelling impact sources and two types of standard impact sources. The hard panels achieve the significant performance in terms of sound wave energy mitigation against the two types of dwelling impact sources, but they show the ineffective performance against the standard impact sources. The hard panels are capable of mitigating floor noise caused by heavy-weight dwelling impacts such as a running child and a jumping man as well as impacts with similar characteristics to the dwelling impacts. Therefore, application of the hard panels to multi-dwelling housing with the aim of mitigating floor noise is practicable.