An improved reconstructing field method for measuring sound reflection coefficient of a large impedance surface at arbitrary incident angles is proposed in this paper. In order to get the reflection coefficient by the...An improved reconstructing field method for measuring sound reflection coefficient of a large impedance surface at arbitrary incident angles is proposed in this paper. In order to get the reflection coefficient by the Spatial Transformation of Sound Fields (STSF), the complex pressure on two parallel planes near by the material surface or the reflection surface must be measured. By the acoustic intensity measurement, the phases of complex pressure on two parallel planes are given. The results of the numerical simulations are shown that the error due to the finite size of the measurement area, and it may be reduced by using a dipole sound source.展开更多
利用扬声器重构声场的传统方法是求解声学逆问题,计算最小二乘意义下次级声源驱动函数,缺点是测量时需要布置大量传感器且只能有效重构声阵列区域附近的声场。为了克服该缺陷,提出利用高阶Ambisonics(higher order ambisonics,HOA)技术...利用扬声器重构声场的传统方法是求解声学逆问题,计算最小二乘意义下次级声源驱动函数,缺点是测量时需要布置大量传感器且只能有效重构声阵列区域附近的声场。为了克服该缺陷,提出利用高阶Ambisonics(higher order ambisonics,HOA)技术重构封闭空间低频声场。针对腔内基于声模态的传播特性,推导了相关重构公式并分析其重构特性。结果表明,当重构参数kr较小时,波数域内格林函数谱分量主要集中于低阶成分且主要由低阶声模态贡献,随着kr的增大,其高阶成分变大且高阶声模态的贡献增大。在重构时,重构滤波器对球阵以外区域的高阶谱分量有明显放大,意味着对测量噪声也有明显放大,而对球阵内部有明显抑制。在此基础上,从声场采集、影响因素及重构效果等方面对HOA与声学逆问题方法进行对比。仿真结果表明,HOA优于声学逆问题方法,对整个声腔都有较好的重构,其重构精度与区域范围取决于球谐函数的截断阶数。最后,在圆柱形舱室模型内进行了实验验证,HOA方法取得了较好的重构结果,展示出良好的工程应用前景。展开更多
文摘An improved reconstructing field method for measuring sound reflection coefficient of a large impedance surface at arbitrary incident angles is proposed in this paper. In order to get the reflection coefficient by the Spatial Transformation of Sound Fields (STSF), the complex pressure on two parallel planes near by the material surface or the reflection surface must be measured. By the acoustic intensity measurement, the phases of complex pressure on two parallel planes are given. The results of the numerical simulations are shown that the error due to the finite size of the measurement area, and it may be reduced by using a dipole sound source.
文摘利用扬声器重构声场的传统方法是求解声学逆问题,计算最小二乘意义下次级声源驱动函数,缺点是测量时需要布置大量传感器且只能有效重构声阵列区域附近的声场。为了克服该缺陷,提出利用高阶Ambisonics(higher order ambisonics,HOA)技术重构封闭空间低频声场。针对腔内基于声模态的传播特性,推导了相关重构公式并分析其重构特性。结果表明,当重构参数kr较小时,波数域内格林函数谱分量主要集中于低阶成分且主要由低阶声模态贡献,随着kr的增大,其高阶成分变大且高阶声模态的贡献增大。在重构时,重构滤波器对球阵以外区域的高阶谱分量有明显放大,意味着对测量噪声也有明显放大,而对球阵内部有明显抑制。在此基础上,从声场采集、影响因素及重构效果等方面对HOA与声学逆问题方法进行对比。仿真结果表明,HOA优于声学逆问题方法,对整个声腔都有较好的重构,其重构精度与区域范围取决于球谐函数的截断阶数。最后,在圆柱形舱室模型内进行了实验验证,HOA方法取得了较好的重构结果,展示出良好的工程应用前景。
