基于统计最优近场声全息的声场重建方法研究

发布时间：2018-08-11 20:13

【摘要】：近场声全息技术是一种高效的噪声源识别、定位及声场可视化技术。该技术由于在目标声源近场进行测量,可以记录到声源辐射中的倏逝波成分,使其重建结果不受瑞利判据的限制,从而大大提高了声场重建分辨率。统计最优近场声全息作为近场声全息技术中的一个重要分支,在大尺寸声源全息重建等方面有其独特的优势。本文在简要介绍近场声全息技术的发展概况和研究现状及存在问题的基础上,主要针对统计最优近场声全息算法在声场重建中存在的一些问题进行了研究和改进。对于常规的统计最优柱面近场声全息和统计最优球面近场声全息中的全息测量面通常要求与目标声源共形的局限性,将基于平面测量的方案引入其中,通过数值仿真验证了该方案的有效性和准确性。同时,该部分也将为全文奠定理论物理基础。针对常规统计最优近场声全息在半自由声场空间多源声场重建过程中重建过程中所需波函数项数多,重建精度不理想的问题,提出了一种基于平面测量的改进统计最优近场声全息算法。与常规算法往往选用单一的波函数来计算声场传递矩阵不同,改进算法通过根据声源的特点选取合适的波函数组合(如单元平面波、单元柱面波和单元球面波)来计算重建过程中的声场传递矩阵,进而重建出目标声源的声场。通过数值仿真验证了该方法的准确性和有效性,并与常规算法进行了详细的对比分析。从总体上看,改进算法与常规算法相比显著提高了重建精度,在不同频率下的相对误差波动较小,鲁棒性更强,且随着频率的增大相对误差有逐渐减小的趋势;此外,不同的波函数组合,重建结果的相对误差差异很大,当选取的波函数与声源共形且数量一致时重建效果较好;最后,重点分析了重建距离对重建结果的影响。对于非自由空间声场重建,则详细介绍了一种基于双层测量的统计最优近场声全息声场分离技术。采用这种声场分离技术,可以对全息测量面两侧均有声源时的声场进行重建研究。通过以上研究,初步建立了一个较为完整的统计最优近场声全息理论体系。
[Abstract]:Near-field acoustic holography is an efficient technique for identifying, locating and visualizing noise sources. This technique can record evanescent wave components in sound source radiation by measuring near field of target sound source, so that the reconstruction results are not limited by Rayleigh criterion, thus greatly improving the resolution of sound field reconstruction. As an important branch of near-field acoustic holography, statistical optimal near-field acoustic holography has its unique advantages in large scale acoustic source holographic reconstruction. On the basis of a brief introduction of the development of near-field acoustic holography, the present research situation and existing problems, this paper mainly studies and improves some problems in acoustic field reconstruction based on the statistical optimal near-field acoustic holography algorithm. For the limitation of the conventional statistical optimal cylindrical near-field acoustic holography and the statistical optimal spherical near-field acoustic holography, the holographic measurement plane is usually conformal with the target sound source. The validity and accuracy of the scheme are verified by numerical simulation. At the same time, this part will also lay the theoretical physics foundation for the full text. Aiming at the problem that conventional statistical optimal near-field acoustic holography needs more terms of wave function and the reconstruction accuracy is not ideal in the process of multi-source acoustic field reconstruction in semi-free acoustic field, An improved statistical optimal near-field acoustic holography algorithm based on plane measurement is proposed. Different from the conventional algorithm, a single wave function is often used to calculate the sound field transfer matrix. The improved algorithm selects the appropriate combination of wave functions according to the characteristics of the sound source (such as element plane wave). Element cylindrical wave and element spherical wave) are used to calculate the sound field transfer matrix in the reconstruction process, and then to reconstruct the sound field of the target sound source. The accuracy and effectiveness of the method are verified by numerical simulation, and compared with the conventional algorithm in detail. On the whole, compared with the conventional algorithm, the improved algorithm improves the reconstruction accuracy significantly. The relative error fluctuates less, the robustness is stronger, and the relative error decreases gradually with the increase of the frequency. With different combination of wave functions, the relative error of reconstruction results is very different. When the selected wave functions are conformal and the number of sound sources is the same, the reconstruction effect is better. Finally, the influence of reconstruction distance on the reconstruction results is analyzed. For non-free space acoustic field reconstruction, a statistical optimal near-field acoustic holographic acoustic field separation technique based on double-layer measurement is introduced in detail. By using this technique, the sound field can be reconstructed when there are sound sources on both sides of the holographic measurement plane. Based on the above research, a relatively complete theoretical system of statistical optimal near-field acoustic holography is established.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB53

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