Acoustic design in open offices aims to reduction of distractions and improvement of speech privacy. Room acoustical design includes high room absorption, high and absorptive screens and appropriate masking sound level. The aim of this study is to show, how these individual design components can affect on room acoustics, using modern room acoustical descriptors. Individual acoustical remedies were studied in four case studies independently. The implemented room acoustical changes were increased ceiling absorption, sound‐absorptive screens, curtains between workers and increased masking sound level. Radius of distraction, rD, spatial decay rate of speech, DL2, and speech level at 4 m from speaker, Lp,S,4m, were determined before and after the room acoustical change. These three simple and robust single‐number parameters are recommended to characterize the acoustic conditions of open offices because they react logically to room acoustical changes.