IMPACT OF TRANSMISSION DELAY IN AUDIOVISUAL COMMUNICATIONS

In this paper, the design and results are presented of an experimental study which was conducted in order to assess subjectively the impact of transmission delay in audiovisual communications. This study was un dertaken using two 64 kb/s videotelephones which were connected over l inks incorporating simulated one-way circuit propagation delays of 0 m s, 250 ms and 500 ms. From the results obtained it was concluded that audiovisual communication is weakly affected by propagation delay. In general, performance degradation between terrestrial and single-hop sa tellite connections was minimal and in most cases statistically insign ificant. A subsidiary conclusion is that the presence of the visual cu es appears to mitigate the impact of transmission delay in audiovisual communication.