Practical design and assessment of architectural speech privacy for closed rooms

Abstract

Practical procedures have been developed for predicting levels of speech privacy associated with closed meeting rooms. The procedures can be used to specify construction designs for rooms intended to provide desired levels of speech privacy. They can also be used for measurement, assessment, and rating of existing rooms. The new approach relates the predicted or measured sound insulation provided by the wall construction directly to the probability that speech will be audible or intelligible to bystanders outside a room. The audibility or intelligibility of speech depends on the relative levels of speech and background noise at the listeners position and can therefore be determined from the speech level inside the room, the sound insulation, and the noise level at the listening position. However, speech and noise levels vary from moment to moment. The measured statistics of these variations can be used to predict the probability that speech will be audible or intelligible outside the room. Wall constructions having higher sound insulation will result in lower probabilities of speech being overheard, and therefore correspond to higher degrees of speech privacy.