In this section methods for presenting information via acoustical means will be presented. In real life humans are able to get a lot of information via the auditory modality. The communication by the means of speech is practiced every day. Even if sometimes we are not conscious about that, we use a lot of non-speech sounds in daily life to orientate and to get precise knowledge of the state of the environment. When acoustical output is used in technical interfaces the way we use sound every day life is adapted to serve as a powerful tool for information transfer. In the following text the underlying concepts or technologies will be presented. It is not the aim of this text to list different synthesis algorithms or to discuss the underlying hardware problems, although they are limiting the widespread use of some interesting methods. The existing audio hardware found in PC and recent workstations will be presented briefly.