中文摘要：

研究虚拟声屏障（Virtual Sound Barrier,VSB）系统在采用不同代价函数时的性能表现。在三维声场分别以声势能密度和、声动能密度和、声能量密度和为代价函数进行数值模拟。结果表明,以声势能密度和为代价函数,降噪效果好,但声压降低量不均匀;以声动能密度和为代价函数,声压降低量最为均匀,但降噪效果不好;以声能量密度和为代价函数,降噪效果最好,声压降低量均匀程度在上述两者之间,是一个比较好的折衷。此外,将声动能密度和与声势能密度和按权重相加构成代价函数Je（w）,针对不同的控制目标,可调整声动能密度和与声势能密度和的权重,得到适合控制目标的最优选择。

英文摘要：

A theoretical comparison of three cost functions is made for Virtual Sound Barrier（VSB） system.Cost functions to be minimized include the sum of acoustic potential energy density,the sum of acoustic kinetic energy density and the sum of the total acoustic energy density at the error sensors.Numerical simulations in three-dimensional sound fields show that minimizing the sum of acoustic potential energy density achieves good control performance but the noise reduction distribution is not uniform in the quiet zone,that minimizing the sum of acoustic kinetic energy density makes noise reduction distribution uniform but the control performance is poor,and that minimizing the sum of total energy density is the best strategy since the control performance is the best and the degree of the uniformity of the noise reduction distribution is between the other two.A new cost function is formed by adding up the sum of acoustic potential energy density and the sum of acoustic kinetic energy density with different weight coefficients.According to different control objective,the best strategy can be attained by adjusting the weight coefficients.