Echo and noise reduction methods for multimedia communication systems

New concepts of echo cancellation and reduction of non-stationary noise affecting audio signals transmitted in telecommunication channels are proposed in the paper. In the both cases, some methods originated form artificial intelligence domain, i.e.: genetic algorithms, neural networks, rough sets are applied. Moreover, in the noise reduction method, some features of the human auditory system are exploited. A number of experiments have been carried out, and a brief discussion on some of them is included.