Integrator's Reference Manual for Polycom HDX ... - 1 PC Network Inc

Integrator’s Reference Manual for Polycom HDX SystemsIt is important to remember that the use of traditional meeting roomdowncans—even those that have color-corrected light sources—for anylighting in the field of view that may include human faces is to be avoided atall costs. These will result in extremely uneven fields of light, or pools, andheavy, unnatural shadows on the faces of the participants.Room Preparation ConclusionWhen we follow the above guidelines we dramatically improve the odds forsuccess in the final deployment of live bi-directional conference-based humancommunications. An added benefit is that this approach dramaticallyenhances the effectiveness of the room as it operates for more traditionalmeetings and presentations. The environment is more comfortable andflexible, and less dependent on specialized electronics for “fixing” deficienciesin the environment.Audio ElementsOnce the space is prepared, we can focus on integration of the variousaudiovisual tools within the environment: audio, video and control.Audio InputThe primary input device for the audio portion of any conference system is themicrophone. Elsewhere in this book [Basics of Audio and Visual Systems Design]we have discussed how these devices operate within a given acousticenvironment. We turn now to a short discussion of how these elementsoperate within a conference environment, where such factors as“three-to-one” rules and “critical distance” often are pushed to the limit orviolated entirely.When sound travels in a room, it follows “the inverse square law.” This meansthat the sound level heard at a microphone drops by a factor of four every timethe distance doubles. Another important consideration in room audio designis the concept of “critical distance,” or the distance at which the loudness of theroom background noise plus reverberation is less than one tenth of theloudness of voices getting to a particular microphone. (This definition is theresult of research conducted by Don and Carolyn Davis. that is referenced inthe chapter “Designing for Intelligibility” in the Handbook for SoundEngineers. 1 )1Davis, Don and Carolyn. “Designing for Intelligibility” in Handbook for SoundEngineers: The New Audio Cyclopedia, ed. Glen Ballou (Indianapolis:Howard Sams & Co., 1991), 1279-1297.A - 8