The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
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On the Errors of the Phased Beam Tracing Method for the Room Acoustic Analysis

실내음향 해석을 위한 위상 빔 추적법의 사용시 오차에 관하여

  • 정철호 (한국과학기술원 기계공학과) ;
  • 이정권 (한국과학기술원 기계공학과)
  • Published : 2008.01.31
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Abstract

To overcome the mid frequency limitation of geometrical acoustic techniques, the phased geometrical method was suggested by introducing the phase information into the sound propagation from the source. By virtue of phase information, the phased tracing method has a definite benefit in taking the interference phenomenon at mid frequencies into account. Still, this analysis technique has suffered from difficulties in dealing with low frequency phenomena, so called, wave nature of sound. At low frequencies, diffraction at corners, edges, and obstacles can cause errors in simulating the transfer function and the impulse response. Due to the use of real valued absorption coefficient, simulated results have shown a discrepancy with measured data. Thus, incorrect phase of the reflection characteristic of a wall should be corrected. In this work, the uniform theory of diffraction was integrated into the phased beam tracing method (PBTM) and the result was compared to the ordinary PBTM. By changing the phase of the reflection coefficient, effects of phase information were investigated. Incorporating such error compensation methods, the acoustic prediction by PBTM can be further extended to low frequency range with improved accuracy in the room acoustic field.

기하음향학 방법들을 이용한 중주파수 해석의 어려움을 해결하기 위하여 소리의 전파에서 위상 정보를 고려한 위상 기하음향학 방법이 제안되었다. 위상 기하음향학 방법은 위상정보를 고려하여 중주파수 대역의 간섭 현상을 설명할 수 있는 장점을 가지고 있다. 그러나 이러한 방법들을 이용하여 소리의 파동성으로 대표되는 저주파수 현상들을 모두 설명할 수 없다. 특히 저주파수 대역에서는 모서리나 장애물에 의한 회절현상을 고려하지 못하여 전달함수나 충격응답의 예측시 오차가 발생한다. 또한 실수인 흡음 계수를 사용한 해석 결과는 측정치와 차이를 보이므로 반사 계수의 잘못된 위상 정보는 교정되어야 한다. 본 연구에서는 균일 회절 이론을 병합한 위상 빔 추적법의 결과를 기존의 위상 빔 추적법의 결과와 비교하였다. 또한 벽면 반사계수의 위상을 변화시키며 위상 정보의 영향을 조사하였다. 제안된 오차 보정 방법들을 이용하면, 좀더 낮은 주파수 대역까지 정확성을 향상시켜 위상 빔 추적법을 실내음향 예측에 적용할 수 있다.

Keywords

References

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