The invention relates to the field of communication and discloses a PSTN
teleconference sound mixing method. The method includes the following steps that S1, voice
active state monitoring is carried out on each member participating a conference, and the members in the voice
active state are added into a sounding mixing
list or a
backup list; S2, updating is carried out on the sound mixing
list at regular intervals; S3,
gain adjustment is carried out on
voice frequency of each member in the sound mixing list; S4, sound mixing is carried out, sound mixing results are output to each member participating the conference, for the member participating the conference which exists in the sound mixing list, output after the
gain adjustment of the member is removed from sound mixing results and then outputting is conducted while for the member participating the conference which does not exist the sound mixing list, the sound mixing results are output. By means of the PSTN
teleconference sound mixing method, influences on effects by echoes and
background noise are reduced, conference quality is effectively improved; the number of sound mixing at the same time is increased, overflowing of mixed sound is avoided, and meanwhile, the volume of the sound will not be changed suddenly; the effect of conference clipping is improved, the difficulty of clipping is avoided, and frequent switching is avoided.