1. X. X. Shen and Y. Shen: ACTA Acoustics Vol. 30(2005), p.324.
2. R. J. M. Craik: Applied Acoustics, Vol. 64(2003), p.325.
3. H. Liang: The video and sound dimming technology of song and dance hall (People's Posts and Telecommunications Press, Beijing 2001).
4. W. W. Zhang, W. H. Tang : Audio Engineering, Vol. 9(2005) , p.16.