Research On Timbre Equalization Of Ambisonics Reproduction

Ambisonics is a series of spatial sound recording and reproduction systems based on physical sound field reconstruction,in which the target sound field is decomposed into spatial harmonics and reconstructed by each order approximation to reproduce the spatial information sound field.Due to its perfect formulation,Ambisonics has been studied extensively since it was proposed in the 1970s.In Ambisonics,the spatial harmonics of each order are coded independently,and the linear combinations of them are decoded into loudspeaker signals to reconstruct the target sound field within a certain frequency range and region accurately.However,due to the limitation of the spatial sampling theorem,errors in the reconstructed sound field occur beyond the upper frequency limit,which may give rise to perceived timbre change.Timbre is an important content to evaluate the effect of spatial sound reproduction.Since perceived timbre is closely related to loudness,equalization of loudspeaker signals can be used to improve the timbre of Ambisonics reproduction.Improper equalization methods may lead to confusion in the location of the virtual source,so it is necessary to evaluate timbre and location performance of Ambisonics reproduction synthetically after equalization.In order to solve the above-mentioned problems,this paper carried out the following work:At first,a spilt-band equalization method was proposed for Ambisonics reproduction system,and compared with existing equalization methods for Ambisonics reproduction.The timbre of horizontal and spatial Ambisonics system is analyzed by binaural loudness model respectively.The analysis of binaural loudness level spectrum indicates that the method we proposed is able to improve the timbre of Ambisonics reproduction effectively,and the effect of equalization is related to the order.Secondly,in order to verify the results of analysis by binaural loudness model,the subjective psychoacoustic experiment was carried out,which compared the timbre and location performance of Ambisonics reproduction with existing equalization method and the proposed equalization.The results of timbre subjective evaluation are consistent with those of objective analysis,that is,the method of spilt-band equalization is able to improve the timbre of Ambisonics reproduction,and the results of virtual source localization experiment show that the spilt-band equalization method we proposed is effective without degrading the virtual source localization performance in Ambisonics reproduction.In this paper,the timbre of Ambisonics reproduction is studied,and the timbre of Ambisonics reproduction system is improved,which provides a reference for further study.