This paper deals with the burst ratio parameter,
which describes the burstiness of a packet loss observed in digital
networks. It is one of the input parameters of E-model –
the most widely used method of assessing conversational quality
of telephony. The burst ratio is defined for one channel
scenario so it can be calculated when the whole transmission
path has been characterized by a single set of parameters. The
main objective of the paper is to extend the burst ratio definition
when the transmission path is defined as a tandem concatenation
of transmission channels being described by their
individual burst ratios. It is assumed that packet loss of a single
channel is described by a 2-state Markov chain. The final
result of the research is an equation describing the burst ratio
parameter when the transmission path consists of multiple
concatenated channels. The derived formula has been validated
by extensive simulations