Analysis with binaural auditory model and experiment on the timbre of Ambisonics recording and reproduction

A scheme for analyzing the timbre in spatial sound with binaural auditory model is proposed and the Ambisonics is taken as an example for analysis. Ambisonics is a spatial sound system based on physical sound field reconstruction. The errors and timbre colorations in the final reconstructed sound field depend on the spatial aliasing errors on both the recording and reproducing stages of Ambisonics. The binaural loudness level spectra in Ambisonics recon- struction is calculated by using Moore＇s revised loudness model and then compared with the result of real sound source, so as to evaluate the timbre coloration in Ambisonics quantitatively. The results indicate that, in the case of ideal ＇independent signals, the high-frequency limit and radius of region without perceived timbre coloration increase with the order of Ambisonics. On the other hand, in the case of recording by microphone array, once the high-frequency limit of microphone array exceeds that of sound field reconstruction, array recording influences little on the binaural loudness level spectra and thus timbre in final reconstruction up to the high- frequency limit of reproduction. Based on the binaural auditory model analysis, a scheme for optimizing design of Ambisonics recording and reproduction is also suggested. The subjective experiment yields consistent results with those of binaural model, thus verifies the effectiveness of the model analysis.