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Purpose: to study the mechanism of temporal bone pneumatization on the occurrence of pulsatile tinnitus (PT) induced by sigmoid sinus diverticulum and/or dehiscence( SSDD). Methods: Four types models of temporal bone pneumatization filled with air and three types models of temporal bone pneumatization filled without air were constructed. Different frequency noises were inputted at the site of sigmoid plate dehiscence and the noise were received and measured at external ear canal. The inputted noise were compared with received noise in difference models. Results: From Ⅰto Ⅳ pneumatization of temporal bone with air, the measured noise were 1/20, 1/9, 1/25, and 1/25 of 125HZ inputted noise, 1/16, 1/9, 1/82, 1/20 of 1/25 of 250HZ inputted noise, 1/13, 1/6, 1/29, and 1/14 of 500HZ inputted noise, 1/23, 1/9, 1/626, and 1/48 of 1000HZ inputted noise, 1.237, 1/53, 1/1248, and 1/44 of 2000HZ inputted noise, 1/1587, 1/299, 1/30059, and 1/2048 of 4000HZ inputted noise, and 1/50500, 1/46011, 0, and 1/23735 of 8000HZ inputted noise at external ear canal respectively. From Ⅰto Ⅲ pneumatization of temporal bone without air, the measured noise were 0, 0, and 0 of 125HZ inputted noise, 1/501187, 0, and 1/79432 of 250HZ inputted noise, 0, 1/100000, and 1/79432 of 500HZ inputted noise, 1/501187, 1/316227, and 1/158489 of 1000HZ inputted noise, 1/79432, 1/63095, and 1/501187 of 2000HZ inputted noise, 0, 0, and 0 of 2000HZ inputted noise, and 0, 1/12589, and 0 of 8000HZ inputted noise at external ear canal respectively. Conclusions: The sounds reduction of high frequency (higher than 1000Hz) was greater than low frequency (lower than 1000Hz) in temporal bone with air. For low frequency sounds, gradeⅡof temporal bone pneumatization was most conducive to sound transmission , followed by gradeⅠ, and grade Ⅳ and grade Ⅲ. For the temporal bone without air, noise at sigmoid plate can not be transmitted to external ear canal.