Preliminary study on the speech privacy performance of the Fabpod

This paper reports the preliminary measurement results for characterising the speech privacy performance of an open ceiling meeting room called Fabpod in RMIT University, where the Speech Privacy Class standardized in the ASTM E2638 was adopted in the measurements to rate the speech privacy performance. The background sound pressure level inside and outside the Fabpod and the sound pressure level differences at different locations inside and outside the Fabpod with different sound source locations were measured in one third octave bands from 50 Hz to 10000 Hz. Based on the measurement results, the Speech Privacy Class of the Fabpod was calculated. The conclusion is that the Fabpod cannot meet the normal speech privacy criteria and the meeting inside the Fabpod can easily be overheard outside. Speech privacy is affected by many factors including the speech attenuation from the sound source to the receiver and the level of the background noise. The speech attenuation from the sound source to the receiver depends on the height of the wall or barrier, the sound absorption coefficient of the ceiling and the distance between the sound source and receiver. To achieve acceptable speech privacy for the Fabpod, all design parameters have to be tuned to near optimum values. The measures that can be used to increase the speech privacy of the Fabpod are discussed.