声频定向扬声器谐波失真测试

Harmonic distortion test for audio directional loudspeaker

依据声参量阵理论,从理论上推导出了声频定向扬声器DSB法、平方根法的自解调理论模型与谐波失真计算公式。在此基础上,以实验对其谐波失真进行了测试。实验结果表明,目前绝大多数声频定向扬声器信号处理方法的理论依据——"Berktay远场解"预测的结果与实验结果存在差异,它只能作为声频定向扬声器信号处理的定性依据。此项研究解决了长期以来声频定向扬声器信号处理理论依据得不到验证的难题,对于研究声频定向扬声器信号处理方法具有重要意义。此外,还明确提出了声频定向扬声器谐波失真的测试不能完全沿用传统扬声器的测试方法,其测试距离应该选择在接近参量阵长度处。

According to the parametric acoustic array theory, the self-demodulation model and the harmonic distortion calculating formulas of the DSB （double side band） method and the square rooting method for audio directional loudspeaker are presented through theoretical derivation. Then, the harmonic distortion of audio directional loudspeaker is tested in experiments. Experimental results prove that the ＂Berktay＇s far-field solution＂ that is the foundation for most of the current signal processing methods of audio directional loudspeaker can only be used as a qualitative foundation for the signal processing of audio directional loudspeaker, because there are differences existing between the experimental results and the predicted theoretical results. This research result solves the problem that the theoretical foundation for the signal processing of audio directional loudspeaker is hard to be verified for a long period, and it is very important for the research of the signal processing method of audio directional loudspeaker. Moreover, it definitely indicates that the harmonic distortion test method for traditional loudspeaker is not suitable for the harmonic distortion test of audio directional loudspeaker without modification, and the distance close to the parametric array length should be chosen as the harmonic distortion test distance.