The cut off points of 90th percentile of acoustic reflex thresholds were determined in the normal and sensory hearing loss.All subjects had measurable hearing(ANSI-1969≤110 dBHL) in three frequencies of 500,1000 and 2000Hz.

While hearing loss was more than 55dB, The cut off point was higher in studies that NR responses was included.

In cases that hearing loss was less than 75dB, 90th percentile can be used in diganosis of retrochochlear lesions.Since Acoustic reflexes are absent in both mentioned pathologies in greater amount of hearing loss,It would be less efficient in diffrential diganisis of cochlear and retrochochlear lesions to use acoustic reflex thresholds under the mentioned circumstances.

Many of the CP angle tumors are acoustic neuroma, vestibular schowanoma or 8^th nerve tumor. This kind of tumor is benign histologically. Big size ones can cause neurological symptoms such as cerebellar imbalance, edema and cranial nerves dysfunction. Acoustic neuroma is mostly unilateral and audio logical findings manifest a unilateral hearing loss. Although big size tumors can lead to bilateral audio logical symptoms which can affect the findings of hearing assessment. Here, a 31 year-old patient suffering right ear vestibular schowanoma have been reported. changes in left ear pure tone results, acoustic reflex measurements and ABR in addition to hearing loss in the right ear have been demonstrated.