Analysis of binaural sound pressure control and virtual source characteristics in stereophonic reproduction

Abstract

In stereophonic reproduction, the manipulation of relative magnitude and phase between two loudspeakers enables to create virtual sources within an azimuth region in frontal–horizontal plane. The law of sine, which is based on evaluating the interaural phase difference and a conventional method for stereophonic analysis at low frequencies, fails to explain some characteristic in stereophonic reproduction, including the influence of span angle of loudspeakers on virtual source localization and the stability of virtual source created by out-of-phase loudspeaker signals. Analogy to the method in active sound control, an alternative method for analyzing the characteristics of virtual source in stereophonic reproduction is presented in this work. On the basis of shadowless head model at low frequency, the power effort of loudspeaker signals for creating virtual source in stereophonic reproduction is evaluated. The results indicate that for frontal virtual source within the span of loudspeakers, the power effort of in-phase loudspeaker signals increases with the increase in the span angle of loudspeakers. For lateral virtual source outside the span of loudspeakers, the power effort of out-of-phase loudspeaker signals increases with the target azimuth of virtual source. Increase in power effort makes the control of binaural pressures difficulty and, thus, virtual source instable.