A novel method for measuring acoustic radiation fields of subwoofers based on non-free-field aspheric measurements

Due to the limitation of the cutoff frequency of the anechoic chamber, it is difficult to measure the low frequency sound field by using the classical method. This paper presents a novel method for measuring the acoustic radiation field of subwoofers. Firstly, according to the sound field separation principle, a general model of spherical harmonics based on the spherical coordinate system is proposed. After that, the coefficients in the spherical harmonic expansion are worked out by the least squares method. And then we use non-free-field aspheric measurements to rebuild the radiated sound fields of the sound source in the free field. Finally, in order to testify the proposed method, simulations of dipoles and multi-poles cases are carried out.