There are significant differences between audio, data and visual communication. First, there is the obvious, audio communications support applications based off sound, data communications supports information displayed numerals or text, and image communications supports pictures, charts or drawings. Although, one similarity is that they all can be transmitted by use of analog or digital.
In regards to audio, this form of communication is an electric signal usually measured by Hz of bandwidth. Different levels of bandwidth are needed for differing scenarios. The text explains, audio teleconferencing needs about 7000HZ of bandwidth in contrast to the 20,000 Hz needed to support two stereo channels of a compact disc. Our next generation digital audio is measured in terms of samples per second.
Data signals is text or character data sent as bit streams and in the form of electromagnetic waves. This is different from the previously discussed audio which is an electric signal represent by bandwidth/samples per second. Adding video signals to the equation, we have a technology that uses a sequence of raster-can images like the text explains. Video signals are characterized by frames per second and can be interlaced or progressive.
Returning to the subject of voice communication, I would like to discuss the difference between private branch exchange (PBX) and VOIP. Private branch exchange is a system in which all the users of a private telephone network share a number of outside