1. A teleconference terminal apparatus which performs speech communications with another terminal apparatus via a network, said teleconference terminal apparatus comprising: an input unit configured to receive a speech signal; an analyzing unit configured to analyze the speech signal received by said input unit and to calculate a target size based on a result of the analysis, the target size representing a coded data size regarded as a target of the speech signal on a predetermined segment basis; a coding unit configured to code the speech signal to generate a data stream, so that the coded data size on the predetermined segment basis becomes the target size corresponding to each of predetermined segments; a stream transmitting unit configured to transmit to the network the data stream generated by said coding unit; a receiving unit configured to receive the data stream transmitted from the other terminal apparatus; a filtering unit configured to determine whether or not segment data is to be decoded on a basis of the data size for each predetermined segment in the data stream received by said receiving unit, the segment data being designated on the predetermined segment basis and included in the data stream; a decoding unit configured to decode segment data determined to be decoded by said filtering unit to generate a speech signal; and an output unit configured to output the speech signal generated by said decoding unit.