Along with the variety of channel bandwidth, there are generally two requirements in the multimedia communication domain, especially for audio signal. One is that the quality of service (QoS) should be hierarchical, and the other is that the bit-rate of source coding should be arbitrarily adjusted for keeping a better QoS. It is evident that a scalable bit-stream with Mutli-Layer is convenient for Unequal Error Protection (UEP) of channel. This paper presents a layering model of audio transmission service a...