The STC were measured for the wall between office/meeting room and the adjacent space and that for the door between the office/meeting room and corridor in front of the room was tested. The receiving room and source room were determined for the test. An office or a meeting room was determined as the source room. The adjacent spaces and corridor were determined as the receiver room.
The background noise levels were measured first in the receiver unit. White noise was generated in the source unit at high level until the sound pressure level in the receiver room and that in the corridor were higher than the background noise level measured of more than 5dB. Then sound pressure levels of the source were measured at 2-3 locations in the source room. The results were recorded in one-third octave bands. After that sound pressure levels were measured at 2-3 locations in the adjacent space and the corridor. The results were recorded in one-third octave bands.