The Journal of the Acoustical Society of Korea ISSN:1225-4428(Print) 2287-3775(Online) 한국음향학회지

The speech privacy of closed office rooms located in a university campus was measured and assessed in terms of SPC (Speech Privacy Class) values. The measurements of two quantities, the LD (Level Difference) between a source and a receiving room, and the background noise level (L_b) at the receiving room were carried out in 5 rooms located in 3 different buildings in the university campus. Each of the 5 rooms was adjacent to both offices and corridors through walls. The TL (Transmission Loss) between the source and the receiver room was also measured to compare the difference of two standard methods, ASTM E2836-10 and KS F 2809. The present results show that the speech privacy of the 5 office rooms is not met the requirement for a minimum SPC values of 70. A minimum LD value of 41 dB between the source and the receiver room should be achieved for having a SPC value of 70 when the mean measured value of L_b at the receiving room is 29.2 dB. That is, the TL(avg) value averaged over the octave bands from 160 Hz to 5000 Hz between the source and the receiver room should be or greater than 40 dB. The most important architectural factor influencing the LD value is the presence of openings, such as doors, and windows, on the adjacent walls between the source and receiving room. Therefore, if the opening of the adjacent wall is replaced by an opening with high sound insulation, the appropriate SPC value of the research and office rooms can be achieved.