The increasing usage of audio and chat communication in private and commercial cooperative settings requires new insight into choosing the appropriate media for collaborative tasks. The paper presents the results of two series of experiments comparing audio and chat communication with varying group sizes. The experimental data indicates that chat scales up better to an increase in group size than audio. We propose that the media richness theory appropriately predicts the productivity of small groups, while the media characteristics proposed by the theory of media synchronicity as well as media speed can be used to predict larger group productivity.