Working in Architecture design studios environment requires various activities. Interaction, communication and meetings could affect the speech intelligibility and the speech privacy conditions. Students Areas with a more silent environment are needed with a minimized level of distraction from surrounding activities, while teamwork and discussion areas with a high level of interaction need a good speech intelligibility. One of the more important elements which can improve the open spaces acoustical conditions is the partitions between workstations.The main purpose of this work is to evaluate the acoustical performance of four partitions types in open plan offices; 1.10m two sides partition height, 1,50m front side partitions, 1,50m one side partitions and 1.50 two sides partitions. This Study was conducted in the College of Architecture, Imam Abdulrhman Bin Faisal University, KSA. Based on ISO 3382-3, Speech Transmission Index, STI in the nearest workstation, Distraction distance rD, privacy distance rP, A-weighted background noise level L,A,B and A-weighted SPL of speech at 4 metres L,A,S,4m have been measured. It was found that the best results can be obtained by 1.50m front side and 1.50m two sides partitions.