Room acoustical conditions in coupled video conference rooms

Abstract

A video conferencing situation combines the acoustical properties of two rooms. The resulting convolution of the two room impulse responses leads to a total impulse response with a reverberation, which is not a classical exponential decay. As a consequence, relationships between parameters such as clarity and reverberation time will be significantly different from those in single rooms, and this will furthermore affect the combination's suitability for speech communication. In this study, a measurement survey is presented from 11 rooms with video conferencing equipment. Their volumes ranged from 24 to 117 m3, and their mid-range reverberation times were between 0.29 s and 0.70 s. Median values were 82 m3 and 0.41 s, respectively. Impulse responses were measured in all rooms and in a subsequent analysis stage, impulse response pairs were convolved, simulating a connection between the corresponding rooms. Those convolved IRs were analyzed in terms of clarity and reverberation time. Recommended parameter values for single rooms were used as guidelines to understand the qualities of convolved rooms.