ASTM METRICS FOR RATING SPEECH PRIVACY OF CLOSED ROOMS AND OPEN PLAN SPACES

This article discusses the relationship between the two metrics, and their suitability for use in any type of space, including spaces not fitting the definition of either open or closed. The E2638 method provides a rating of the average performance of a closed room - without any assumptions as to talker location - to each of a number of listener positions outside the room, close to the room boundaries. E2638 includes a table of categories that identifies the frequency with which speech sounds would be audible or intelligible for various SPC values. The high correlation for both metrics implies both are useful for rating intelligibility over a wide range. The two current ASTM metrics for rating speech privacy of building spaces are highly correlated, and both seem well suited for use in conditions where speech is intelligible, such as in open plan spaces.