水声材料插入损失测量中的声波多途效应抑制方法

提出了一种在非自由声场中测量水声材料插入损失时抑制多途效应的方法,称为"虚拟端射阵技术"。通过仿真设计,采用逐点移动分时发射信号的方式破坏各路径同频反射干扰的相干性,并在阵长方向形成尖锐的指向性,将上述所有位置的信号延时叠加消除干扰杂波,最后提取所需波形实现对材料插入损失的计算。在尺寸为5.5 m×3.5 m×3.5 m非消声水池中对1.1 m×1.0 m×8 mm的铝板和直径0.5 m、厚8 mm的圆形铝板进行了测量,测量频率范围为3~20 kHz。结果表明虚拟端射阵技术相比于常规方法能降低测量频率下限,矩形铝板和圆形铝板的有效测量频段内误差均小于0.5 dB,有效减少了声波多途效应的干扰。该方法的实现提高了非消声水池中单换能器测量水声材料的能力。 

A restraining multipath effect method for the measurement of insertion loss of underwater acoustic materials

A method suppressing multipath effect when measuring the underwater acoustic materials in a reverberant field is proposed,which is called "virtual end-fire array technology".To damage the coherence of the same frequency reflection interference of each path,signal of different phase at different positions was transmitted by a single transducer in the simulation design,and a sharp directionality in the direction of the array length was formed.Signals all at the above positions were superimposed to eliminate the clutter.The insertion loss of the material was finally calculated by the desired waveform.In the measured frequency range of 3~20 kHz,the aluminum panel with size of 1.1 m×1.0 m×8 mm and the round aluminum panel with 0.5 m in diameter and 8 mm in thickness were measured in a reverberant tank with size of 5.5 m×3.5 m×3.5 m Results showed the measured lowest effective frequency limit can be reduced by the virtual end-fire array technology compared with the conventional method.Measuring round aluminum panel and rectangular aluminum panel,error in the effective measurement band was less than 0.5 dB and the interference of the acoustic multipath propagation effects was reduced effectively.Ability of one single transducer in reverberant tanks to measure acoustic materials is improved after this method implemented.