Speech Intelligibility Measurements in an Office Building

This study investigates how changes to an emergency voice communication system (EVCS) or the building environment affect speech intelligibility in four spaces of an office building: lobby, stairwell, dining area, and open-floor-plan office space. Effects of additional or alternate speaker locations, floor and wall coverings, and background noise on intelligibility are measured via objective means (i.e., meters that evaluated the speech transmission index (STI) of a test signal broadcast via the EVCS). Current practice recommends measurement spacing that appears to appropriately characterize the single-floor spaces, although changes to the environment can reduce STI measurements by nearly 20%. Several suggestions address concerns of when and where to perform speech intelligibility testing.