A Study on the Insertion Loss of Noise Barrier with the Variation of Top Shape

방음벽 상단부 형상에 따른 삽입손실 연구

  • 정성수 (한국표준과학연구원 음향진동그룹) ;
  • 김용태 (한국표준과학연구원 음향진동그룹) ;
  • 이우섭 (아산정보기능대학 멀티미디어과)
  • Published : 2002.10.01

Abstract

The insertion loss of the noise barriers with several top shape is measured in an anechoic room by using a reduced scale model test. The insertion loss differences between a straight vertical barrier having 0.3 m height and several barriers with simple top shaped are compared. The results show that the latter is more effective than the former and absorptive barrier is more effective than the reflective one. Among the barrier types of 'T', 'Y', and '(equation omitted)', type 'Y' is the best one and the rest have similar effect. This result is well agree with Alfredson (PIOC. Inter-Noise 95, p. 381, 1995)'s but contradict to May (J. Sound Vb. 71, p. 73, 1980)'s. Therefore, it is difficult to determine which type is the best. In order to find out this discrepancy, boundary element method is adopted and the result shows one can have different result because each supposed different experimental conditions like height of noise barrier, positions of sound source and receiver, etc.

방음벽의 상단부 형상에 따른 삽입손실을 무향실에서 모형축척 방법으로 측정하고 상호 비교하였다. 높이 0.3m의 수직형 방음벽에 대한 삽입손실과 간단한 형상물을 상단부에 설치한 방음벽의 삽입손실과의 차를 비교하였다. 실험결과 단순히 높이를 증가시키는 경우보다 상단부에 간단한 형상을 설치한 것이 더 효과적이었다. 'T'형, 'Y'형 및 '(equation omitted)'형 방음벽에 대한 삽입손실을 비교한 결과 'T'형과 '(equation omitted)'형 방음벽은 비슷하였으며 'Y'형이 가장 좋은 효과를 나타냈다. 본 연구결과는 Alfredson(PIOC. Inter-Noise 95, p. 381, 1995)등의 결과와는 잘 일치하지만 May (J. Sound Vib. 71, p. 73, 1980) 등의 결과와는 상충된다. 따라서 어떤 형태가 가장 좋은지를 결정하는 것은 어렵다. 왜 이러한 상호 모순되는 결과를 얻게 되는가를 알기 위해 경계요소법을 적용한 결과 각 연구자들마다 다른 방음벽의 높이, 음원과 수음점의 위치, 높이와 거리를 서로 다른 실험조건을 가정했기 때문임을 알 수 있었다.

Keywords

References

  1. J. Acoust. Soc. Am. v.55 Diffraction of sound around comers and over wide barriers A.D.Pierce https://doi.org/10.1121/1.1914668
  2. J. Sound Vib. v.69 On calculation of sound fields around three dimensional objects by integral equation methods T.Terai https://doi.org/10.1016/0022-460X(80)90436-8
  3. J. Acoust. Soc. Am. v.86 The insertion loss of finite length barriers on the ground A.L'Esperance https://doi.org/10.1121/1.398337
  4. J. Acoust. Soc. Am. v.87 Model study of the sound propagation behind barriers of finite length R.Princhieva https://doi.org/10.1121/1.399177
  5. Appl. Acoust. v.1 Noise reduction by screens Z.Maekawa https://doi.org/10.1016/0003-682X(68)90020-0
  6. Appl. Acoustics v.42 Using Maekawa's chart to calculate finite length barrier insertion loss Y.W.Lam https://doi.org/10.1016/0003-682X(94)90122-8
  7. J. Sound Vib. v.71 Highway noise barriers: new shapes D.N.May;M.M.Osman https://doi.org/10.1016/0022-460X(80)90410-1
  8. J. Acoust. Soc. Am. v.75 Model studies of barrier performance in the presence of ground surfaces Part Ⅱ- different shapes D.A.Hutchins;H.W.Hones;L.T.Russell https://doi.org/10.1121/1.390993
  9. PIOC. Inter-Noise 95 Special shapes and treatment for noise barriers R.J.Alfredson;X.Du
  10. SYSNOISE Manual Rev. 5.3 Anon.
  11. J. Sound Vib. v.193 Noise prediction models to determine the effect of barriers placed alongside railway lines J.J.A. van Leeuwen https://doi.org/10.1006/jsvi.1996.0267
  12. 日本音響學會紙 v.54 Determination of acoustic property for improved noise barriers Technical Committee on Noise and Vibration