Today, noise pollution is a major problem in the environment through percussion sounds, and airborne and background noise in buildings, resulting in lack of sound comfort and proper distribution of sound in architectural spaces. According to the use of spaces, the degree of importance of this issue is different. In open-plan offices, the presence of unpleasant noise creates problems for users. For this reason, speech privacy and speech clarity are of great importance and attention in these spaces. The purpose of this study was to reduce harmful reflections and proper distribution of sound in open-plan offices. In this research, the acoustic indicators of materials and the physical form of an open-plan office space were investigated. The research was based on the correlation method and investigation of architectural independent variables and acoustic dependent variables. The selected sample was calculated by AHP method and simulated in Edeon software in several administrative office stations. Two different types of geometry (high-corner roof and low-corner roof) with two different materials (polished materials and textured materials) were investigated. Reading time (RT) and speech transmission index (STI) were drawn and calculated in Edeon software to create speech privacy. The results showed that the closest figures to the international standards were obtained by using forms with a higher number of levels and composite materials such as (plaster and mineral fibres) which caused higher sound absorption and speech clarity and an optimal increase in conversation privacy.