What is Privacy Index (PI)?
The American Society Testing and Materials (ASTM) defines the Privacy Index (PI) as a rating index of the degree of speech intelligibility from as built private offices and conference rooms. It reflects the amount of speech that is on-average unintelligible from outside a closed private office. The higher the PI, the more difficult it is to understand the nature of the conversation occurring inside a private office. PI is not a direct percentage, but an exponential ratio, so PI = 50 is not 50% privacy. A PI of 50 is actually rather poor privacy. The average open office plan with acoustical ceiling tiles, industrial carpet, and partitions still has a PI typically lower than 50. Only by adding the correct amount of soundmasking can the PI improve to above 80, the point at which surrounding speech stops being a distraction. Yet, in the typical private office a PI in the lower 70s is common, making the “private” part of “private office” a fallacy. Confidential speech privacy is defined by
