Case study of construction issues affecting speech privacy in legal offices

Abstract

During the design phase of a project, theoretical calculations for how a space will acoustically perform are often used. However, improper construction practices and other factors such as incompatible manufacturer combinations can lead to large discrepancies between theoretical performance and field-tested performance. The project in question consisted of a renovation of an existing legal office suite with a waffle ceiling and wide window spans. The primary acoustical concern was sound isolation from office to office and from private offices to open office space. A confidential level of speech privacy was the design goal as the suite contained multiple legal consultation rooms. Existing exterior glazings spanned the length of multiple offices, so an acoustical mullion was specified. Full perimeter door seals and automatic door bottoms were also installed. This paper details how the measured performance of this suite of offices was significantly lower than the designed Sound Transmission Class (STC) rating due to issues with the acoustic mullion installation as well as different door seal, door frame, and door manufacturer incompatibilities.