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.

Background: hearing loss is a major health care problem that tends to retard the developmental milestones of children. It takes early detection and intervention to avoid a permanent loss in acquisition of speech and cognitive functions. Hence, the importance of hearing screening in all children especially in the developing world for accurate statistics and early intervention is clear. This work was aimed at predicting hearing in children by means of acoustic reflex measurements
Method: In this study which was performed in 1995, 146 ears(86 children aged between 5-10years old referring to audio logy clinic in Tehran university of medical sciences between august 1995 and February 1996) were evaluated (amongst 95 were normal and 51 ears with SNHL<84dB).the methods Niemeyer and Destrehan formula ,Lilly2 equation, un weighed Sensitivity prediction by acoustic reflex, weighed sensitivity prediction by acoustic reflex to establish their clinical viability.
Results: findings demonstrated that weighed sensitivity prediction by acoustic reflex(WASPAR) have a good correlation with conventional audiometric evaluation(K=.78) and also it has good sensitivity, Specificity , Negative predicted value(NPA) and positive predicted value (PPV).
Conclusion: In case that conventional audiometry is not applicable, WASPAR is a good objective choice in lieu of subjective tests.

Method and Materials :this cross sectional descriptive and analytic survey was done at Golestan navy hospital in Tehran, between June 1998 and March 1999 on total of 69 male subject (104 ears, ) 50 acoustic trauma & 54 noise induced H.L) between 20 to 40 ears old.
Results:1- The mean acoustic reflex threshold at 1 kHz showed there is no significant difference between two groups.
2- The intensity elicited maximum reflex amplitude at 1 kHz didn&apost produce at a significant linear correlation with subject&aposs age and ear canal volume in both groups.
3- The intensity elicited maximum reflex amplitude in NIHL group wasn&apost shown a significant correlation with ear compliance and gradient.
4- The mean Intensity (SPL) elicited maximum reflex amplitude in NIHL group was more than mean intensity (SPL) in acoustic trauma group.
5- The mean intensity (SL) elicited maximum reflex amplitude in NIHL group was More than mean intensity (SL) in acoustic trauma group.
Conclusion: Acoustic reflex amplitude is reduced for subjects with NIHL compared with acoustic trauma subjects.

Objective: This study was aimed to survey the hearing status of the patients with definite MS. The results of this study may help to confirm the diagnosis and to improve our knowledge of different aspects of this disease and to optimize the treatment and rehabilitative techniques.
Material & Methods: This study is performed in audiology clinic of rehabilitation science faculty of Iran medical science university as an assesive-analytic procedure in winter of 2000 in 40 MS patients (Referred from the MS clinic of Shohada Hospital) of 20 to 45 years old. All the patients have no history of otologic problems. The results of conventional audiologist tests (PTA, SRT, SDS, imittance audiometry) and ABR findings of MS patients were compared to the results of control group.
Results: The differences between the means of low, high and mid frequency PTAve in MS patients and control group were statistically significant (P<0.05). There was no significant difference between two groups in the speech test&aposs results, statistically. The results of ART test show statistically significant differences between experimental and control groups. The only differences in ABR results were seen for the absolute latency of the wave V and IPLs (I-V, III-V) between two groups. The amplitude ratio of V/I in MS patients 1.5 was within the normal range (0.5 to 2). There was a statistically significant relationship between mean of mid frequency PTAve and prolongation of absolute latency of the wave V. The relationship between ABR and SDS and also between ART and ABR were not statistically significant. Finally, the results of this study suggested that low, high and mid frequency PTAve, ART, absolute latency of the wave V, and IPLs III-V, I-V can be used ascomplementory method to confirm the diagnosis of MS with other conventional methods such as: MRI, CSF analysis, SEP and VEP.

Objective: OAE an audiologic study for diagnosis of exteracochlear auditory neuropathy.
Method & Material: Immitance audiometry, OAE and ABR and rehabilitation Intervention was performed for 3 children suffered from kernictrus.
Conclusion: 1) OAE in the from of screening, distorted product and transient evoked-otoacoustic emission has to be added to our audiology test battery. 2) OAE studies have their own merit when we are clinically involved with the diagnosis of especial clinical entities like neonatal hypoxia, kernicterus, multiple sclerosis, meningitides and meningoencephalitis. 3) Case selection for cochlear implantation needs a knowledge of patients' OAE results. 4) In the case of intracerebral auditory neuropathy the need for other rehabilitative measures will be better understood.

Background and Aim: Contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) test evaluates the efferent auditory system. In this test, acoustic reflex is an important confounding variable. In recent years, application of this test is growing especially in children suspect to central auditory processing disorder. Therefore, the magnitude of influence of this confounding variable on the suppression of TEOAEs should be made clear. The aim of this study was to investigate the impact of acoustic reflex on contralateral suppression of TEOAEs.
Methods: This research was performed on 39 normal-hearing adults of both sexes and of 18-26 years of age. Tests were used for the determination of interaural attenuation (IA), acoustic reflex, TEOAEs and contralateral suppression of TEOAEs.
Results: TEOAEs amplitudes and their contralateral suppression were significantly higher in females and males respectively (p=0.01). The amount of TEOAEs suppression before reflex activity ranged between 2000 to 3000 Hz. Activation of acoustic reflex significantly increased the magnitude of suppression in all frequency bands (p≤0.01) and maximum suppression occurred in 500 to 1000 Hz.
Conclusion: For achieving accuracy of clinical findings, clinicians should always use suppressant levels lower than the acoustic reflex threshold. It is recommended that different norms for males and females be used in contralateral suppression of TEOAEs.