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.

The most common contributing factors in inducing hearing loss in adults are aging, exposure to noise and the interaction among these factors with other parameters. Individual parameters are also effective in the extent of hearing loss which is produced. Being aware of Vulnerability factors such as physical parameters, Auditory and non-auditory factors can be useful in considering a good hearing conservation program for noise induced hearing losses.In the current article we are aimed at introducing three important parameters and their sub-divisions pertaining to this issue.

In addition to Stimulus frequuncy and level, emitting Inner ear structurs status, OAEs parameters depend on conductive sound pathways charactristics, so abnormal OAEs donot always represent cochlear abnormality. Middle ear transmites Vibrations in two directions: forward and backward. Middle ear pathologies affect both forward and backward transmission.In this paper, The purpose is investigation of immediate effects of tympanic over - and under - pressure on click evoked Otoacoustic Emissions (CEOAEs) in healthy individuals. Healthy subjects with normal hearing and middle ear were exposed to ambient pressure changes in a pressure champer. The pressure was progressively changed in 100 dapa steps to accomplish on increase and decrease  in tympanic pressure. Pressure equilibration of the middle ear was avoided. The relative tympanic over-and under - pressure (+/-320 dapa) was monitored by tympanometry and CEOAEs recorded at every step of tympanic pressure change. The CEOAEs recorded during progressive tympanic over-and under- pressure had reduced amplitude and shorter latencies that were most pronounced in the 750 to 3000 Hz frequency bands.

Arachnoid cysts are cerebrospinal fluid-filled sacs that are located between the brain or spinal cord and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. They are usually located within subarachnoid space with a membrane consisting of arachnoid cells and collagen fibers and are filled with CSF. It is naturally considered as a congenital cyst because of its common appearance in the infancy. Typical symptoms of an arachnoid cyst around the brain include headache, nausea and vomiting, seizures, hearing and visual disturbances, vertigo, and difficulties with balance and walking. MRI and CT can help in diagnosis. Arachnoid cysts are benign and the vast majority remains asymptomatic throughout life. If they are deemed to be causing symptoms then surgery can be contemplated. Here, we are aimed at describing a case of Arachnoid cysts involved cerebellopontine angle that has been reffered to audiology clinic in Tehran University of Medical Sciences. The experiments and results of radiographic techniques has been brought here.

Method & Material: This study was performed on 36 normal-hearing subjects aged 18-25 years for survey of temporary threshold shift (TTS) by transient evoked otoacoustic emissions. Finding: Noise can affect the pure-tone thresholds and (TEOAEs) amplitudes. When cochlea affected by noise, evaluating TEOAE is more suitable than pure-tone audiometry. Because of this test, is objective an unaffected by attention and alertness and can be evaluated in difficult to test subject and also have high carefulness and can be performed in a quiet, but not sound-proof room.

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.

Background and Aim: One of the most significant complaints of children with learning disability (LD) is difficulty in understanding speech in the presence of background noise. Different studies have shown that the medial olivocochlear bundle(MOCB) may play a role in hearing in noise. The MOCB function can be evaluated by the contralateral suppression of tone burst evoked otoacoustic emissions (TBEOAEs).The aim of the present study was to evaluate frequency specifications of MOCB by the contralateral suppression of TBEOAEs at 1,2,3 and 4 KHz in response to contralateral white noise in LD students.
Materials and Methods: This case-control study was conducted on 34 LD students aged 7-11 years and 31 normal students matched for age.The contralateral suppression of TBEOAEs was evaluated by comparing TBEOAEs amplitudes with and without contralateral white noise.
Results: In the absence of noise there was no significant difference between TBEOAEs amplitudes of two groups. In the presence of noise significant decrease was seen in TBEOAEs amplitudes at 1,2,3 and 4 KHz in both groups. In LD students the amount of this decrement at 1,2 and 4 KHz was lower than in the normal students.
Conclusion: A significant diminished suppression effect at 1,2 and 4 KHz in LD students indicates that at these frequency regions MOCB function was reduced. Therefore its suggested that the assessment of MOCB by evaluating the suppression effect of TBEOAEs included in the test battery approach used in the diagnostic of LD students.

Background and Aim: Learning disability(LD) is one of the most prevalent problems among elementary school children. Approximately 10 percent of all elementary school children suffer from this problem. It has been determined that learning disability is predominantly accompanied with subtle impairment in central auditory nervous system. The main idea of this study was to evaluate middle latency auditory evoked potential (MLAEPs) in learning disabled children.

Materials and Method: This cross-sectional study investigated middle latency auditory evoked potential in children with learning disability (n = 31) compared to normal children (n = 31). Latencies and amplitudes of MLAEPs results with different stimulus intensity and binaural stimulation were compared between two groups.

Results: Compared to control group, learning disabled children exhibited smaller amplitudes for all the components except the right ear Na and Pa. There is no significant difference between two groups for latencies of the components.

Conclusion: It seems that middle latency auditory evoked potential may be useful in diagnosis and evaluation of learning disabled children although more investigation is required.

Background and Aim: Analysis of transient evoked otoacoustic emissions(TEOAEs) is of considerable interest due to their close relation with cochlear mechanisms which reveal cochlear function.The particular structure of TEOAEs requires a method with both a satisfactory time and frequency resolution. Among different methods the time –frequency techniques are the most suitable approaches. The aim of this study was to investigate the differences between neonate’s cochlear function and adult’s cochlear function using time –frequency approaches in TEOAEs.

Materials and Method: The data of this cohort study was obtained from a sample of 23 normal neonates, aged between 1-28 days, and 31 normal adults, aged between 18 -25 years.TEOAEs with click stimulus were performed for both ears .The TEOAEs files were investigated in time – frequency transform software in off-line mode. The signal to noise ratio(SNR) and response level (dB) of TEOAEs were analysed.

Results: The reproducibility, SNR and response level in neonates was greater than adults and in both groups there were no significant difference between responses of males and females and of the right and the left ears.

Concolusion: There are differences between neonate’s and adult’s cochlear response. High frequencies responses are stronger in neonate’s cochlea.

Background and Aim: Internal Evaluation means assessment of abilities and potentials. To promote the quality of education, research, health and finally rehabilitation is one of the most important roles and responsibilities of the universities. Promotion of quality of the theoretical and practical education for the Audiology students provides this major with its final goal that is to serve society. The purpose of this study was to evaluate the strength, weaknesses, opportunities and threats (SWOTs) of the Audiology department and to identify the ways of diminishing weaknesses and threats.
Materials and Methods: This descriptive cross-sectional study was conducted on undergraduates, postgraduates, graduates, academic staff, and the director of Audiology department in 9 areas, including management flowchart, educational programs, instructional methods and curriculum models, students, educational areas and equipments, graduate, academic staff, research, and treatment. Data were collected by questionnaires. Results were analyzed descriptively and were expressed in raw and percentage.
Results: The scores of areas in two measures were as follows: management flowchart 4.36 (87.31%), educational programs 4.17 (83.58%), instructional methods and curriculum models 4.01 (80.26%), students 3.43 (68.60%), educational areas and equipment 3.60 (72.11%), from the view of undergraduates, post graduates, faculties, graduates 3.60 (72.03%), academic staff 4.03 (80.6%), research 3.52 (70.4%), and treatment 4.54 (90.80%). The highest score was, therefore, of the treatment area and the lowest belonged to the educational area and equipments. The score of the Audiology department, as the main factor was 3.89 out of 5 which was 77.88%.
Conclusion: Audiology group total score indicates the desirable status that can be promoted to the most desirable if SWOTs are considered.

Background and Aim: Middle latency auditory evoked potentials (MLAEPs) development takes longer time than the auditory brainstem response (ABR) development does, which makes them difficult to record in some children. The purpose of this study was to investigate the age effect on characteristics and detection of MLAEPs in children and adults.
Materials and Methods: This cross sectional study was conducted on 15 children aged   7-12 yr and 31 adults aged 20-50 yr with normal peripheral hearing. To investigate precisely, children were divided in two subgroups of older and younger than 10 years old, as well. The MLAEPs amplitudes and latencies were recorded by conventional protocol and compared.
Results: Adult Na mean latency, 20.86 ms, was less than that of children, 22.86 ms, (p=0.0025).  In contrast, the adult Nb mean latency, 44.93 ms, was longer (p=0.0001). Children Nb mean latency was 42.02 ms. There was no significant difference in MLAEP amplitudes and latencies between two children subgroups, although variance was more in younger children.
Conclusion: MLAEPs are reliably recorded after 7 years old. Characteristics of MLAEPs are different in adults and children so that the primary MLAEPs generators have a course of development extending beyond the first decade of life. As those potentials were recorded in all children, it is suggested to be used in their test batteries for hearing evaluation.

Background and Aim: One of the most important problems of children who suffer from autism is abnormality in receiving and integrating sensory inputs, especially hearing input. It has been shown that brainstem has a key role in receiving, encoding and integrating hearing input. Auditory brainstem response (ABR) is a tool by which we can evaluate this function. The purpose of this study was to assess and to compare autistic and normal children brainstem hearing function.
Materials and Methods: This case-control study was conducted on thirty (58 ears) autistic and thirty (57 ears) normal 6-12 years old children. The children with autism were divided into slight and severe subgroups according to Autism Diagnostic Interview-Revised questionnaire. Click-evoked ABR was recorded and compared between groups.
Results: There was significant difference between two groups V and III wave latencies and I-III and I-V interpeak latencies (p<0.05). In fact, comparison of the results of autism subgroups with normal children indicated that the latencies of the severe subgroup significantly prolonged.
Conclusion: Increasing latencies of ABR waves in severe subgroup maybe due to abnormality in low level of brainstem. Brainstem abnormality may result in exacerbating the symptom of autism. It is therefore suggested that ABR is included in diagnostic test batteries for these patients.

Background and Aim: Blocking of the adenosine receptor in central nervous system by caffeine can lead to increasing the level of neurotransmitters like glutamate. As the adenosine receptors are present in almost all brain areas like central auditory pathway, it seems caffeine can change conduction in this way. The purpose of this study was to evaluate the effects of caffeine on latency and amplitude of auditory brainstem response(ABR).
Materials and Methods: In this clinical trial study 43 normal 18-25 years old male students were participated. The subjects consumed 0, 2 and 3 mg/kg BW caffeine in three different sessions. Auditory brainstem responses were recorded before and 30 minute after caffeine consumption. The results were analyzed by Friedman and Wilcoxone test to assess the effects of caffeine on auditory brainstem response.
Results: Compared to control group the latencies of waves III,V and I-V interpeak interval of the cases decreased significantly after 2 and 3mg/kg BW caffeine consumption. Wave I latency significantly decreased after 3mg/kg BW caffeine consumption(p<0.01).
Conclusion: Increasing of the glutamate level resulted from the adenosine receptor blocking brings about changes in conduction in the central auditory pathway.

Background and Aim: Tinnitus is a common symptom among lots of people but little is known about its origins. This study was aimed at comparing the Auditory Steady-State Response (ASSR) thresholds in normal cases and patients with subjective idiopathic tinnitus (SIT) in order to diagnose its real origins.
Materials and Methods: This case-control study was conducted on 19 patients with tinnitus and 24 normal cases aged 18-40 yr.The patients underwent broad medical tests to roll out any background reason for their tinnitus. ASSR thresholds were estimated in both groups at 20 and 40 amplitude modulation. The patients were selected from tinnitus patients in Research Center in Hazrat Rasoul Hospital, Tehran, Iran.
Results: The mean ASSR thresholds at 40HZ modulation were worse in tinnitus patients compared to normal ones (p<0.05) but no significant statistical differences was detected at 20HZ. These results were found in both situations in which we averaged both ears thresholds and when we estimated the thresholds of the ears separately.
Conclusion: It seems that the origin of the responses of the modulation of 40Hz, primary auditory cortex, midbrain regions and subcortical areas, in these patients is involved or the origin of their tinnitus is related to some kind of problems in these areas, although more investigation is needed about 20Hz.

Background and Aim: Following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In order to investigate this process, event-related potentials provide accurate information about time course neural activation as well as perception and cognitive processes. In this study, the latency and amplitude of auditory P300 were compared in sighted and early blind individuals in age range of 18-25 years old.

Methods: In this cross-sectional study, auditory P300 potential was measured in conventional oddball paradigm by using two tone burst stimuli (1000 and 2000 Hz) on 40 sighted subjects and 19 early blind subjects with mean age 20.94 years old.

Results: The mean latency of P300 in early blind subjects was significantly smaller than sighted subjects (p=0.00.( There was no significant difference in amplitude between two groups (p>0.05).

Conclusion: Reduced latency of P300 in early blind subjects in comparison to sighted subjects probably indicates the rate of automatic processing and information categorization is faster in early blind subjects because of sensory compensation. It seems that neural plasticity increases the rate of auditory processing and attention in early blind subjects.

Background and Aim: Recently, more attention was paid to the direct protective effect of aldosterone against hearing impairment in elderly patients. The aim of this study was determination of possible correlation between serum aldosterone level and hearing condition of elderly patients that referred to the Otolaryngology services of Hamadan in 2005-2006.

Methods: In this case control study 54 (27 males,27 females) persons above 60 years old were evaluated. They contained twenty eight cases with normal hearing and 26 cases with presbycusis. Persons with any abnormal biochemical finding or history of conditions that predispose them to the sensorineural hearing loss (SNHL) were excluded. In both groups serum level of sodium, potassium and aldosterone were measured and hearing condition evaluated by puretone, speech and immitance audiometry.

Results: Statistical relationship between serum aldostrone level and hearing condition, sex, configuration of audiogram and speech discrimination score (SDS) were not significant. In addition, no significant relationship between sodium and potassium levels with hearing condition was found (p>0.05). Conclusion: This study could not confirm protective effect of aldostrone against presbycusis. This discrepancy may originate from epidemiologic differences, laboratory errors or small sample size.

Background and Aim: Previous studies suggest that auditory stimulus frequency in normal subjects contribute to both P300 amplitude and latency measures. As occipital cortex devotes to other modalities including auditory inputs, the purpose of this study was to determine the effects of stimulus frequency in early blind subjects.
Methods: fifteen early blind subjects (8 males and 7 females) with mean age of 25.13±4.27 years were tested. Cognitive potential P300 was recorded in response to high (1000/2000 Hz ) and low (250/500 Hz) frequencies auditory stimuli using an oddball task in 70 dB nHL. While participants answered to target stimulus, amplitude and latency of P300 was recorded.
Results: With high frequency stimuli, mean amplitude in early onset blind subjects obtained 14.13 ±5.53µv and was 17.59±8.17µv with low frequency. With high and low frequency, mean latency of P300 obtained 295.60±31.33ms and 317.38±21.71ms respectively.
Comparison of results between two stimuli showed that there were statistically significant differences between amplitudes (p=0.008) and latencies (p=0.001) of cognitive potential P300.
Conclusion: Changing low frequency to high frequency results in decreasing both amplitude and latency. It seems that auditory stimuli frequency affect the P300 parameters in blind subjects.

Background and Aims: Main feature of auditory processing abilities is temporal processing including temporal resolution, temporal ordering, temporal integration and temporal masking. Many studies have shown the superiority of blinds in temporal discrimination over sighted subjects. In this study, temporal processing was compared in congenital blind subjects with sighted controls via gap in noise test (GIN).
Methods: This analytic-prescriptive non-invasive cohort study was conducted on 22 congenital blinds (11 males and 11 females) with a mean age of 26.22 years and 22 sighted control subjects (11 males and 11 females) with a mean age of 24.04 years with normal hearing in faculty of Rehabilitation Tehran University of Medical Sciences. Gap in noise test results, approximate threshold and percent of corrected answers, were obtained and then, were analyzed by Mann-Whitney non-parametric statistical test.
Results: There was a significant difference in the approximate threshold and the percent of corrected answers between congenital blinds and sighted control subjects (p<0.05). However, there was no significant difference between males and females in this regard (p>0.05).
Conclusion: Auditory temporal resolution ability, the lower approximate threshold and the more corrected answers in gap in noise, in blind subjects is better than the sighted control group and it might be related to the compensative neuroplasticity after visual deprivation.

Background and Aim: Neurotologic signs and symptoms, especially vestibular symptoms, are common in migraine patients. The goal of this study was to investigate some parts of the central vestibular system using some subtests of videonystagmographic evaluation, including spontaneous nystagmus, gaze-evoked nystagmus, and smooth pursuit between their attacks of migraine.
Methods: Thirty patients with migraine and 38 healthy volunteers of 18-48 years of age were included in this study. Spontaneous nystagmus, gaze-evoked nystagmus toward the right, left and upward, and also smooth pursuit using three different velocities were performed in both groups.
Results: Five normal subjects and five migraine patients had spontaneous nystagmus, which was less than three degrees there was no statistically significant difference between the two groups. No gaze-evoked nystagmus was seen in both groups. In one velocity of smooth pursuit evaluation, gain and phase were significantly different. The statistical difference in gain and phase was not clinically important as it was in normal range of the device. Another statistically significant parameter was saccadic morphology of smooth pursuit which was seen in migraine patients.
Conclusion: These results suggest the presence of subtle otoneurological abnormalities in migraine patients that is probably due to deficiency of oculomotor function with vestibulocerebellar origin.