A server receives, from each of a plurality of participant devices in a communication session, a respective one of a plurality of audio streams. The server estimates an audio energy of each of the plurality of audio streams and determines whether to perform a transform on at least one of the plurality of audio streams. If so, the server performs the transform on the at least one of the plurality of audio streams and transmits the at least one of the plurality of audio streams to at least one of the plurality of participant devices.