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: To determine SOAE,TEOAE, and DPOAE, characteristics in normal -hearing school boys.
Method and Material: This cross-sectional study was conducted on 7-11 year-old normal -hearing boys (n = 100) living in 12th zone of Tehran. OAEs also performed and investigated if otoscopy, pure tone and immittance audiometry were normal. Both handedness and ear effects was also considered.
Results : 31% had SOAEs. No significant differrence between the right and lefe ear SOAEs frequency and amplitude means. 1,3 kHz and total response TEOAEs amplitude was significantly different between two ears. There was no significant difference between both ear DPOAEs amplitudes, whereas the letf-handed boys&apos DPOAE amplitude is greater than the right -handed ones&apos amplitudes.
Conclusion : As some results including equal SOAEs of both ears , no difference between both ears SPOAEs amplitude , and handedness effect on the amplitude do not agree with other studies , these finding should be considered in testing OAEs of school boys.

Objective : To assess neonates and children suffering from meningitis , during the critical and recovery periods , using ABR , EOAE and Behavioral Audiometry.
Method and Material: 40 neonates to 12-year-old children were assessed. Using ABR test, the hearing of these cases was evaluated during the critical period-that is , 24-72 hours following the diagnosis. This test was repeated when patients recovered from meningitis-that is 24 hours before discharge (recovery period) Hearing function , again , was assessed 7-14 days following discharge through Immittance Audiometry, Behavioral Audiometry (PTA , SF and BOA). And EOAE (TEOAE and DPOAE) tests procedures.Findings: During the critical period , ABR test revealed normal hearing in 35 patients (87.5%) and severe to profound sensorineural hearing loss (unilateral and bilateral) in 5 patients (12.5%-girl=4, boy=1). The same result were obtained in re-evaluation in the recovery period. On the other hand , 7-14 days after of discharge , Immittance Audiometry and Behavioral Audiometry (including PTA , S.F and BOA tests), confirmed the mentioned results (cross - gcheck). EOAE test (DPOAE and TEOAE) in 35 normal hearing patients (according to ABR test) , showed normal cochlear function. 2 out of 5 cases suffering from severe to profound sensorineural hearing loss revealed normal cochlear function. According to EOAE results , abnormal cochlear function was evident in 3 patients.
Conclusion: ABR , EOAE tests , and Behavioral Audiometry in children meningitis during the critical period and recovery period can be used to diagnose any degree of hearing loss with a high level accuracy. The results of persent study is confirmed by previous investigations.

Background and Aim: High frequency audiometry (HFA) provides a valuable tool and optimal index for distinguishing and monitoring many pathologies of the ear. The purpose of this study was to measure the reliability of HFA threshold in children.
Materials and Methods : In this cross-sectional study , 100 normal-hearing children, of 7 to 13 years old, including 50 boys and 50 girls were examined with a Belton 2000 audiometer and Sennheiser HD 250 earphones in Pediatric Clinic  of Audiology Department, Faculty of Rehabilitation of Tehran University of Medical Sciences.
Results: The threshold differences between right and left ears in two test sessions, were not significantly different except for 14 KHz. HFA threshold in two test sessions showed no significant difference in all frequencies between girls and boys but 16 and 20 KHz in right ear and 10 KHz in left ear.
Conclusion : The test-retest thresholds for iudividual ears showed ±0-10 dB SPL for difference at least  in 99.74 % of ears at all frequencies that is clinically reliable and acceptable.

Background and Aim: Auditory neuropathy is an hearing disorder in which peripheral hearing is normal, but the eighth nerve and brainstem are abnormal. By clinical definition, patient with this disorder have normal OAE, but exhibit an absent or severely abnormal ABR. Auditory neuropathy was first reported in the late 1970s as different methods could identify discrepancy between absent ABR and present hearing threshold. Speech understanding difficulties are worse than can be predicted from other tests of hearing function. Auditory neuropathy may also affect vestibular function.

Case Report: This article presents electrophysiological and behavioral data from a case of auditory neuropathy in a child with normal hearing after bilirubinemia in a 5 years follow-up. Audiological findings demonstrate remarkable changes after multidisciplinary rehabilitation.

Conclusion: auditory neuropathy may involve damage to the inner hair cells-specialized sensory cells in the inner ear that transmit information about sound through the nervous system to the brain. Other causes may include faulty connections between the inner hair cells and the nerve leading from the inner ear to the brain or damage to the nerve itself. People with auditory neuropathy have OAEs response but absent ABR and hearing loss threshold that can be permanent, get worse or get better.

Background and Aim: Noise-induced hearing loss is the most common problem in industrial areas. This study aimed to determine effects of excessive noise exposure on measurable characteristics of distortion product otoacoustic emissions (DPOAEs) in rabbits.
Methods: The study was carried out on 12 adult male New Zealand White rabbits including case group - exposed to 500-8000 Hz broadband white noise with 100 dBA SPL for 8 hours per day in 5 consecutive days - and control group. After three days period of acclimatization to the experimental condition, rabbits&apos hearing status in each group were measured by distortion product otoacoustic emissions on days zero means before the study was initiated as a baseline, eight, one hour after the latest exposure to noise, and ten. The recorded results were analyzed using SPSS software.
Results: Highest mean distortion product otoacoustic emissions amplitudes in case group were allocated to frequencies of 5888.50 Hz, 8166.50 Hz, 9855.00 Hz, 3956.00 Hz, and 3098.50 Hz, respectively. However, the lowest mean distortion product otoacoustic emissions amplitude was related to frequency of 588.00 Hz (p=0.001).
Conclusion: This study revealed that distortion product otoacoustic emissions amplitude shifts due to noise occur first in high and then in middle frequencies. Additionally, exposure to noise can decrease distortion product otoacoustic emissions amplitudes. We conclude that distortion product otoacoustic emissions can be a reliable test for estimating personal susceptibility to noise-induced hearing loss.