When choosing a video conferencing system ,it is natural for the potential buyer to look very closely at the quality of the audio. In order to assure a high-quality video conferencing, it is important to have a good picture, but it is vital to have high quality audio. The reason for this is that most of the information transferred in a video conference is actually in the audio channel. Not only is good audio mandatory to the effective exchange of information exchange of information, it has also been found that it can effect the perceived video quality. In this ape several key issues on audio quality are discussed. Since audio delay is among the most vexing problem, each video conferencing system has to make efforts to shorten it. What causes audio delay, how to measure actual delay and how to shorten it is provided in detail. Finally several strategies about system design are presented in order to improve audio quality. All the above are based on the video conferencing systems developed according to H.324 and suitable to video conferencing system implemented all using software.