The sound which actually exists
En route to answering them, one must first consider the traditional approach to acoustics, which relies on “categorization” and “acceptable-level” schemes prevalent throughout building standards and codes. The former specifies sound-rating values (e.g. sound transmission class [STC], noise isolation class [NIC], impact isolation class [IIC], ceiling attenuation class [CAC]) for the boundaries of a room or building envelope, while the latter uses noise-rating values (e.g. noise criteria [NC], noise rating [NR], room criteria [RC]) to set maximum limits for noise, such as those generated by building systems, services, and utilities. However, neither offer insight into the “actual acoustics” (i.e. the sound actually present) within a space or occupant experience of it.
To improve results—a goal one can call “better acoustics”—and fulfil the objective of designing with occupants in mind, one must focus on the sound actually present in a space and look at it through the lens of both architectural acoustics (i.e. the study of sound and its behaviour in and due to a space) and psychoacoustics (i.e. the study of the psychological and physiological effects of sound and its perception). Either one cannot be separated from the other, as psychoacoustical evaluation of a space considers the outcome of the combined performance of all acoustical features.
Acoustical privacy is key
The reactions of building occupants are captured using psychoacoustic metrics, some of which are subjective (e.g. surveys evaluating comfort, distraction, perceived productivity) and others that are objective (e.g. intelligibility, audibility).
Research shows one’s overall acoustical satisfaction is strongly correlated with acoustical privacy, a concept with clear ties to the workplace, but is also relevant to other environments. Although people tend to equate acoustical privacy with speech privacy, the former is not limited to the intrusion of speech content; it also considers the audibility of unintelligible speech and other types of noise. For example, surveys of multi-unit residences demonstrate links between acoustical privacy and annoyance, fatigue, and sleeping problems (e.g. due to noise from traffic and neighbours).2
It is challenging to use acoustical privacy as a starting point for a conversation about acoustical equity. The science around acoustical privacy is not sufficiently nuanced; it is not yet addressed by a standardized metric or even a proposed methodology.
