A model for optimising the size of speech parcels for use on packet switched networks carrying real time interactive speech

An initial hardware/software model has been developed to assess the ability of a local area network (LAN) employing the Technical Office Protocol (TOP-IEEE 802.3), to carry interactive speech while heavily loaded with data traffic. The intelligibility of the speech is subjectively assessed for both unidirectional and bidirectional transmissions. The packet structure of CSMA/CD network being used is such that the minimum data packet size is 46 bytes. In the interests of efficiency, successive speech sample (packets) have been grouped together in parcels and loaded into the data section of the CSMA/CD frame for transmission. Subjective results have been obtained as to the optimum parcel size for reasonable user acceptability