Methods and Materials:This cross - sectional analytical study examines the clinical utility of the external ear resonance (EER) peak amplitude measurement as an index of the possible middle ear effusions. The EER peak amplitude and frequency of 180 ears in 98 children of 7-9 years old were recorded. 120 of them (30 girls & 30 boys) had normal hearing and showed type A tympanograms. The remomder (60 ear of 38 boys) showed type B tymoanograms. These children were examined at the clinic of audiology department, rehabilitation faculty, Tehran University of medical sciences and health services, year 1376 hijri.The tests included: 1) Otoscopy, 2) Pure tone air - condition test, 3)Tympanometry and 4) E.E.R peak amplitude and frequency measurement through test - retest.
Results: 1- The average of E.E.R peak frequency for normal hearing girls, normal hearing boys and hearing impaired boys is 3206 Hz (SD=564), 3202 Hz (SI)- 634) and 2953 (SD=37l) respectively.
2- The average of E.E.R peak amplitude is 16.0 dB SPL (SD=2.6), 16.6 dB SPL (SD= 3.0) and 23.5 dB (SD=3.0) for normal hearing girls, normal hearing boys and hearing impaired boys respectively.
3- The correlation of the mean of E.E.R peak amplitude and frequency for two normal groups, girls and boys, is not significant (p>0.0l).
4- The mean test/retest variability in the E.E.R peak amplitude is 16.0 dB SPL and 3.1 Hz for frequency. These results indicate high validity and consistency of E.E.R characteristics measurements.
5- E.E.R peak amplitude is significantly ccre1ated with the presence of type B tympanogram (p-0.00) we find a 6.9 dB SPL increase in average E.E.R peak amplitude in boys with type B tympanograms in comparison to boys with
type A results but correlation of average E.E.R peak frequency of two groups is significant too (p=0.00).
* The results are valid only within the context of this research.
* The results of this research have been compared with similar studies in abroad.

Background: In recent years there has been increased interest in the use of Al for assessing hearing handicap and for measuring the potential effectiveness of amplification system.AI is an expression of proportion of average speech signal that is audible to a given patient, and it can vary between 0.0 to 1.0.
Method and Materials: This cross-sectional analytical study was carried out in department of audiology, rehabilitation, faculty, IUMS form 31 Oct 98 to 7 March 1999, on 40 normal hearing persons (80 ears 19 males and 21 females) and 40 hearing impaired persons (61 ears 36 males and 25 females, 25-65 years old) with moderate to moderately severe SNI-IL The pavlovic procedure (1988) for calculating Al, open set taped standard mono syllabic word lists, and the real -ear probe- tube microphone system to measure insertion gain were used, through test-retest.
Results: 1/A significant correlation was shown between the Al scores and the speech recognition scores of normal hearing and hearing-impaired group with and without the hearing aid (P<0.05) 2/ There was no significant differences in age group & sex: also 3 In test-retest measures of the insertion gain in each test and 4/No significant in test-retest of speech recognition test score.
Conclusion: According to these results the Al can predict the unaided and aided monosyllabic recognition test scores very well, and age and sex variables have no effect on its ability. Therefore with respect to high reliability of the Al results and its simplicity, easy -to- use, cost effective, and little time consuming for calculation, it&aposs recommended the wide use of the Al, especially in clinical situation.

Methods and Materials: Investigation of electrically evoked auditory brain stem response (EABR) is a new issue, especially in implanted patients. Experiments were performed in C.I Center of Iranian Institute for Science and research expansion,1996 on 30 implanted patients with 22 spectra and MSP cochlear implant system and 30 normal subjects with the range of 3-33 years.Findings:1- EABR was obtained in the implanted patients.2- Absolute latency of EABR waves is 1-1.5 ms shorter than ABR waves ‘P<0.05).3-Absolute latency of wave V decreases as a function of electric stimulus magnitude (P<0.05).4- No significant difference was observed in IPL Ill-V between ABR and EABR.

Objective: determining difference limen for Frequency (DLF)in string musicians.
Materials &Methods: This case-control study was conducted on 15 string musicians with musicianship > 10 years (30 ears) and 15 normal hearing subjects (30 ears). They all were male and 20-30 years old. DLF was measured after otoscopy and immitance audiometry and pure tone audiometry.
Results: DLF was significantly different between two groups of case and control. DLF in musicians is less than the normal hearing subjects.
Conclusion: It seems that familiarization with notes results in better DLF in musicians comparing to others.

Background and Aim: Hearing sensitivity is so vital for musicians as loud music can cause hearing loss. The aim of this study was to assess hearing sensitivity of musicians in order to determine the effects of music exposure on hearing organ.
Materials and Methods: This case-control study  was conducted on 15 string musicians with musicianship history of more than 10 years and 15 normal hearing subjects. They all were male and 20-30 years old. TEOAEs and DPOAEs performed after otoscopy , immittance and pure tone audiometry in octave frequencies between 250 to 16000 Hz.
Results: There is not significant difference between pure tone thresholds of two groups for all frequencies.A significant difference of TEOAE is found between two groups for total response and amplituds of TEOAEs . DPOAEs amplituds are not significantly different between two groups .
Conclusion: Musicianship may  affect TEOAEs amplitudes , but cannot affect results of PTA and DPOAEs. Therefore this can be useful to detect cochlear lesions secondary to music exposure and also as a tool in hearing protection program.

Background and Aim: Since knowing the mechanisms which evoke non-fluency is the first step in the treatment of stuttering, and there are very few researches in Persian which consider the role of the linguistic factors behind  stuttering , this study is an attempt to provide answers to some of numerous questions about stuttering by comparing  the stuttered words` type in stuttered children and adults. 
Materials and Methods: In this study stuttered people were divided into 5 age groups as follows: 3-6, 7-9, 10-12, 13-16, and older than 17 years old. Each group had ten participants. Forty-two of the 50 participants were male , and the youngest person was 3 years old and the eldest one was 32 years old. The study method involved recording at least 5 minuets of spontaneous speech of every one who was diagnosed of suffering from stuttering by two speech and language pathologists. The percent of non-fluency on every word&aposs type was determined where a content word was followed or preceded by a function word (Function-Function-Content words and Function-Content words contexts). Then these findings were analyzed by Kruskal-Wallis and Mann-Whitney tests. 
Results:  The results of this study show while function words are dominantly more stuttered than content words in children less than 13 years old in Function-Function-Content words context, we consider more disfluency on content words and second function word by getting old. We consider more stuttering on function words in children less that 13 years old in Function-Content words context too and increased non-fluency on content word by growing up. Results also show meaningful differences between the fifth group and others in the amount of stuttering on second function word in the Function-Function-Content words contexts and also between the first group and the others in amount of non-fluency both on function and content words in Function-Content words context.
Conclusion: people who stutter from Farsispeakers populations exhibit almost differential patterns of disfluency in different ages. Young speakers who stutter are predominantly disfluent on function words. There is an exchange of disfluencies from function to content words as speakers get older. Disfluencies on both function and content words are so rarely in Function-Content words and Function-Function-Content words contents. These findings support the view that stuttering on function words in children is a way of getting time to complete the next content word&aposs plan. These exchange findings are similar to what is found in English and Spanish languages and explained by the EXPLAN model.

Background and Aim: The purpose of this research is to study the standardization of speaking and reading rates in a group of normal speaker of female students, and to compare them. As the rate of speech is an important variable in the evaluation and treatment of stuttering, cluttering, dysarthria and apraxia.

Materials and Method: One hundred of second grade students of primary school and an equal number of fifth grade students participated in this study. All subjects were native speakers of Farsi, who passed an informal, screening test of articulation and speech. None of the subjects had a history of speech, hearing, or neurological disorders. The subjects were asked to read from the 180 words portion of their Farsi book and tell story. Their speech was recorded by using a tape recorder. Then the data were analyzed for word and syllable rate. In transcribing the samples, single morpheme was counted as single word and compound words were counted as two words if they had two free morphemes. Non-word interjections were excluded from word and syllable counts while word interjections and repeated words were included in the count. Independent t-test and paired t-test were used for analyzing.

Results: In the second grade students the reading rate is, on the average, 189.4 syllable per minute (SPM)(94.9 word per minute(WPM), 3.1 syllable per second(SPS)) and the talking rate is 189.8 SPM (99.1 WPM, 3.1 SPS) and in the fifth grade student the reading rate is 223.9 SPM (119.0 WPM, 3.7SPS) and the talking rate is 210.26 SPM (109.5 WPM , 3.4 SPS).

Conclusion: The result highlight that in the fifth grade students, reading rates are higher than talking rates while in the second grade they are not, because they do not have enough skills for whole word reading. A remarkable finding in this research is that, reading and talking rates in the fifth grade students are higher than the second grade students.

Background and Aim: The short-term memory (STM) has been studied to a great extent so far. Using some strategies and techniques to help the subject to access to his/her memory is important for Speech pathologist. Priming is a process that increases the chance of accessing to some information of memory by means of some simulations. So, primings are some words which facilitate the retrieval of the target words. The purpose of this study is comparing phonological and semantic priming on the short verbal memory span.
Materials and Methods: The research was conducted on sixty-four 18-25 year-old male students in Tehran University of Medical sciences. Due to some distortion factors, including bilingualism, stutter-ing, and articulation problem, that can effect the reaction time, were determined as exclusion critenia. In additiion, subjects with difficulty in Wepman auditory discrimination were ruled out. The test was performed via the second version of programmed DMDX software and reaction time was recorded.
Results: Semantic tasks and rhyming tasks were retrieved faster than the other tasks in lexical access respectively. There was a significant difference between the semantic and rime tasks but there is no significant difference between alliteration and unrelated tasks.
Conclusion: The result of this research indicates that the semantic level is activated faster than the other levels and the phonological level is activated right after that. The alliteration level is the last level that activated. It has some similarities with some other investigations on the reaction time in phono-logical tasks

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: Tinnitus is an unpleasant sound which can cause some behavioral disorders. According to evidence the origin of tinnitus is not only in peripheral but also in central auditory system. So evaluation of central auditory system function is necessary. In this study Auditory brainstem responses (ABR) were compared in noise induced tinnitus and non-tinnitus control subjects.
Materials and Methods: This cross-sectional, descriptive and analytic study is conducted in 60 cases in two groups including of 30 noise induced tinnitus and 30 non-tinnitus control subjects. ABRs were recorded ipsilateraly and contralateraly and their latencies and amplitudes were analyzed.
Results: Mean interpeak latencies of III-V (p= 0.022), I-V (p=0.033) in ipsilatral electrode array and mean absolute latencies of IV (p=0.015) and V (p=0.048) in contralatral electrode array were significantly increased in noise induced tinnitus group relative to control group.
Conclusion: It can be concluded from that there are some decrease in neural transmission time in brainstem and there are some sign of involvement of medial nuclei in olivery complex in addition to lateral lemniscus.

Background and Aim: Vestibular evoked myogenic potentials (VEMP) originate from the saccule and the inferior vestibular nerve. In this study, the prevalence of VEMP and latency of the p13 and n23 were compared between three groups of individuals, including symptomatic and asymptomatic Meniere's disease cases and normal participants.

Methods: This study was conducted on 42 cases with the mean age of 40.48 years thirty were Meniere's disease patients, of which 19 were symptomatic and 11 were asymptomatic twelve were normal participants. The VEMP were recorded with 500 Hz tone bursts at 120 dBpeSPL. Then the prevalence and latency of the waves were analyzed and compared in the three above mentioned groups.

Results: The prevalence of VEMP in symptomatic Meniere's disease patients (52.6%) was significantly less than asymptomatic individuals (90.9%) and also normal subjects (100%)(p<0.05). There was no significant difference between latencies of the waves in these three groups (p>0.05). The latency of p13 for symptomatic, asymptomatic and normal participants was 16.41, 15.20 and 14.14 ms, respectively and the latency of n23 for these groups was 20.25, 18.77 and 18.50 ms, respectively.

Conclusion: In Meniere's disease, after medical management, the succule probably regains normal function resulting in re-existence of VEMP. It seems that there is no change in the latency of the waves, most likely due to involvement of the inner ear and intactness of the nerve. VEMP may be a useful test for diagnosis of Meniere's disease and additionally for monitoring the trend of medical management.

Background and Aim: 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 musicians in temporal discrimination over non-musicians. In this study we compared temporal processing in musicians and non-musician controls via Gap in Noise (GIN) test.
Methods: This cohort study was conducted on 24 musicians with mean age of 25.3 years and 24 normal hearing non-musician controls with mean age of 24.5 years, in Faculty of Rehabilitation of Tehran University of Medical Sciences. GIN test results (approximate threshold and percent of corrected answers) obtained and analyzed by Mann-Whitney non-parametric statistical test.
Results: There was significant difference between approximate threshold and percent of corrected answers between musicians and non-musician group (p<0.001), while no sex difference was observed between both groups (p>0.05).
Conclusion: the lower approximate threshold and the more corrected answers in GIN test by musician group indicate rapid auditory temporal processing ability of this group rather than non-musicians group. This might be related to effects of musical training on central auditory processing.

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: Multiple sclerosis (MS) is a neurological disorder that involves central nervous system. Studies have showed that multiple sclerosis affects behavioral central auditory tests, such as masking release or masking level difference (MLD). The purpose of this study is to compare the masking level difference between multiple sclerosis patients and normal subjects.
Methods: This cross sectional and non-interventional study was conducted on 32 multiple sclerosis patients aged between 20-50 years and 32 controls matched for age and gender in Faculty of Rehabilitation, Tehran University of Medical Sciences. masking level difference test was performed on each subject.
Results: The mean masking level difference in the two groups was significantly different (p<0.01) however, gender did not prove to play a role in this difference.
Conclusion: As part of the multiple sclerosis diagnosis panel, masking level difference test is an efficient modality for evaluation of hearing impairment and monitoring of rehabilitation progress.

Background and Aim: Patients with type I diabetes mellitus commonly complain about dizziness, floating sensation, tinnitus, weakness, and sweating. The aim of this study was comparing vestibular evoked myogenic potentials (VEMPs) between these patients and normal people.

Methods: Twenty-four patients with type I diabetes mellitus and twenty-four healthy volunteers with the age range of 15-40 years were enrolled in this study. A tone burst of 500 Hz, with the intensity of 95 dB nHL, was delivered through a insert earphone and vestibular evoked myogenic potential was recorded. The t-test was used to compare the results between the two groups. To investigate the effect of glycated hemoglobin (HbA1c) on VEMP responses (latency, absolute and relative amplitude), the regression analysis was used.

Results: The mean p13 and n23 latency were significantly more in patients with type Ι diabetes mellitus (for P13 latency, p=0.013 in right and p=0.010 in left ear, and for n23 latency, p<0.001 in right and p=0.005 in left ear). There was no significant difference between two groups in absolute and relative amplitude and prevalence of the VEMP (p>0.050). There was no correlation between VEMPs and HbA1c in patients with type 1 diabetes mellitus (p>0.05).

Conclusion: Prolonged latencies of the VEMP in patients with type 1 diabetes mellitus suggest lesions in the retrolabyrinthine, especially in the vestibulospinal tract. Nevertheless, due to the limited number of examined samples, further investigation with more patients should be performed.

Background and Aim: Diabetes mellitus is a metabolic disorder that affects multiple systems including the auditory and vestibular systems. Patients with diabetes mellitus complain of tinnitus and dizziness. The objective of this study is to assess the effects of diabetes mellitus types I and II on auditory and vestibular systems.

Methods: We compared pure-tone audiometric results and cervical vestibular evoked myogenic potentials ( cVEMPs) between 15 patients with diabetes mellitus type I (43.80 with SD 4.246), 15 patients with diabetes mellitus type II (48.13 with SD 2.973), and 10 normal volunteers (45.30 with SD 4.448). Age range of the participants was 40-50 years old.

Results: Audiometric results showed normal hearing in both types of diabetes mellitus. In contrast, comparing amplitude of cVEMPs between diabetes mellitus and control groups showed statistically significant differences (p<0.05).

Conclusion: In spite of normal audiometric results in patients with diabetes mellitus types I and II, there was abnormal vestibular responses involving vestibular end-organ and related central pathway.