hear their own words transmitted back at them. echo cancellation A process that uses a mathematical process to predict an echo and remove that portion of the signal from an audio waveform to eliminate acoustical echo. Video Communication: the Whole Picture echomodeling A mathematical process whereby an echo is created from an audio waveform and, subsequently subtracted from that form. The process involves sampling the acoustical properties of a room, calculating approximately what form an echo might take, and then removing that information from the signal. echosuppression The insertion of mild attenuation in audio transmit and/or receive signal paths. Used to reduce annoying echoes in the audio portion of a videoconference, an echo suppresser is a voice-activated "on/off" switch that is connected to the four-wire side of a circuit. It silences all sound when it is on by temporarily deadening the communication link in one direction. Unfortunately, echo suppression clips the remote end's new speech as it stops the echo. Electrical Interface Association, a standards-setting group in the US that defines standards for interfaces including jacks and other network connections. Extended Industry Standard Architecture. The independent computer industry's alternative to IBM's Micro-Channel data bus architecture that IBM used in its PS/2 line of desktop computers. EISA is a 32-bit bus or channel that expands on the original Industry Standard Architecture (ISA) 16-bit channel. EISA capabilities are particularly important when a machine is being used for processor-intensive applications. electromagnetic spectrum The range of wavelengths that includes light, physical movement of air (sound) or water, radio waves, x-rays, etc. These wavelengths propagate throughout the entire universe. electromagnetic waves Oscillations of electric and magnetic forces that produce different wavelengths and which include light, radio, gamma, ultraviolet, and other forms of energy. electron beam A stream of electrons focused on a phosphorescent s