In the current article we will have a look at the evolusion of audiological tests. Based on the Olsen's theory,having  knowledge about the history of audiological evaluation is not a click="function onclick() { this.style.backgroundColor='#b5d5ff'return hotWord(this) }" onmouseout="function onmouseout() { this.style.backgroundColor='transparent' }" onmouseover="function onmouseover() { this.style.cursor='default' }">platitudinous issue, Rather an audiologist should have a comprehensive knowledge about it and be involved in its progress. In this way he can attain enough expertise and science to make use of the technology.The oldest history regarding to this issue goes back to the 16th century,although It should be considered that other  related investigations about sound, hearing and related fields has heretofore been performed and the relevant investgigators should not be ignored.

Here we have mentioned the case of  a Caucasian man affected with human immunodeficiency virus during blood injection in a heart surjury.He demonstrated vertigo, dissequilibrium and neurological problems secondry to his disease 4 years later. Auditory and vestibular system disfunction became obvious based on the neurological examinations. optokinetic nystagmus, ataxia in addition to lack of response by caloric stimulation was attained in electronystagmographic examination.absolute latencies and interpeak intervals were prolonged in the auditory brain-stem responses(ABR).abnormal low scores were obtained in SSI test bilaterally.organic brain lesion and severe anxiety have been diagnised during psychological examination.Human immunodeficiency virus was detected in brain, cerebellum and brainstem cells by means of autopsia.meanwhile the pathologic changes were cosistent with neuro-otological findings.

Functional Neurochemistry is one of the fields of studies in the auditory system which has had an outstanding development in the recent years. Many of the findings  in the mentioned field had led not only the basic auditory researches but also the clinicians to new points of view in audiology.

Here, we are aimed at discussing the latest investigations in the Functional Neurochemistry of the auditory system and have focused this review mainly on the researches which will arise flashes of hope for future clinical studies.

It is difficult for clinicians to make parents aware of any disease or permanent handicap of their children.It is crucial to have vivid picture of the reactions to such crisis in order to manage severe psychological effects of the mentioned situations such as depression and unhappiness. Confronting the situation parents have diverse feelings regarding the pregnancy period, birth time and handicap diagnosis and these are the factors that shape the parent’s upcoming reactions. Common feedbacks to the crisis are refusing the problem, keeping their child away from society, the emotions that provoke disappointment, asking about the reasons for hearing loss, referring to religion, condemning the physician, feeling sin and changing doctor frequently. When parent accept the situation and that hearing could not recurrent and understanding the natural reasons back on their child’s handicap, they can manage the situation constructively.

We aimed at discussing some common auditory disorders in children with dyslexia. In such patients delayed reading, memory dysfunction, spatial and visual perception and hearing abnormalities are reported with various degrees.Investigations have not led to distinct findings about the etiology of the abnormality. We will discuss this abnormality with an audiological point of view.

Since common audiometric evaluations are performed by subjective tests in which patient&aposs cooperation is required, the importance of systems which are made to obtain auditory evoked potentials in infants, young children and difficult-to- test patients can be accentuated. This article firstly refers to the theory of the mechanism and function used in designing the auditory evoked potentials systems and then the procedure of planning and producing this instrument is explained.

Auditory perceptual and visual-spatial characteristics of subjective tinnitus evoked by eye gaze were studied in two adult human subjects. This uncommon form of tinnitus occurred approximately 4-6 weeks following neurosurgery for gross total excision of space Occupying lesions of the cerebellopontine angle and hearing was lost in the operated ear. In both cases, the gaze evoked tinnitus was characterized as being tonal in nature, with pitch and loudness percepts remaining constant as long as the same horizontal or vertical eye directions were maintained. Tinnitus was absent when the eyes were in a neutral head referenced position with subjects looking straight ahead. The results and implications of ophthalmological, standard and modified visual field assessment, pure tone audio metric assessment, spontaneous otoacoustic emission testing and detailed psychophysical assessment of pitch and loudness are discussed.

Masking is a necessary part in ABR test the same as other Audiological experiments to obtain the real responses without the intrusion of the other ear. In the current research we are aimed at studying the effect of the masking noise on the pure latency of wave V and interwave latencies of I-III, III-V and I-V. Noise was delivered to the non test ear with intensities of 0, 30, 50 and 70 dB in four different sessions while the intensity level of the stimulus was fixed in all four sessions.

Many pregnant women are exposed to noise in the workplace. Noise can affect both fetus and pregnancy of pregnant women. Hormonal disturbances and nanism are of devastating effects of noise. An increased risk of shortened gestation has been shown in four studies Results. In a third study showed the length of gestation in female infants to be inversely correlated to maternal residential noise exposure. Decreased birth weight has also been associated with noise exposure in pregnant women.Some of the adverse impacts of exposure to noise is discussed here as an investigation report.

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.

Sounds situated in a certain domain of intensity can evoke auditory system physiologically. Permanent and continuous stimulation which is produced by such sounds would not be harmful to hearing organ.  This safe intensity is estimated 61 dB SPL. However one should pay attention that in case the intensity of mechanical sound wave increases (more than 75 dB SPL), the exposure time should be decreased unless the serious harm to auditory system is expected.  Auditory system can be affected due to sound harms in two major types: Permanent threshold shift and temporary threshold shift which can be described as the changes in hearing status of human caused by the exposure to sententorian sounds. Numerous physiological factors can exacerbate the devastating effects of sounds that we are aimed at an overall description on this issue in the present review article.

Vestibular Schowanoma is one of the most common Intracranial Tumors which has elicited from the Schwann cells in the upper part of vestibular branch of 8^th nerve and can affect the cochlear branch too. This benign capsulated tumor  is mostly unilateral. Schowanoma is relatively slow growing.In the current article we have presented the case of a 51 year-old woman complaining Right ear Tinnitus accompanying with numbness of the right side of the face without any sign of vertigo or imbalance. MRI and Auditory Brain stem Responses (ABR) studies demonstrated right side vestibular Schowanoma next to cerebellopontine Angle (CPA). The audiological and imaging findings have been brought here in details.

Objectives: Introducing an approach for diagnosing the normal ABR independently or supplementary used to confirm the results of the other approaches.
Materials and Methods: This study was carried out in a descriptive manner on 31 male students of audiology in the Rehabilitation Faculty which were not chosen randomly. All of the samples aged between 18 to 25 years old with normal hearing and with no history of hearing disorder. They were tested in the winter of 1377 by ABR. The resulted of their ABR tests (62 curves) were in accordance with the convenient latency norms. After the preparation stage, the frequency analysis of the curves was considered through the Fast Fourier Transform function.
Results: considering the power and phase spectrum, three components are recognized, and phase for their frequency, amplitude and phase are determined.The normative values of the obtained amounts of the frequency, amplitude and phase for the frequency analysis results of the normal ABR curves are as follows:* First Component: Frequency: 340-530 Hz, Amplitude: 23-31 dB, Phase: 0-3 radian * Second Component: Frequency: 540-370 Hz, Amplitude: 20-30 dB, Phase: 0.3-2.7 radian * Third Component: Frequency: 750-1024 Hz, Amplitude: 19-30dB, Phase: 0-3.3 radian
onclusion: The results of the present study are exclusively valid for the society being considered, and their generalization requires more researches.

Studying auditory discrimination in children and the role it plays in acquiring language skills is of great importance. Also the relationship between articulation disorder and the ability to discriminate the speech sound is an important topic for speech and language researchers.Previous event- related potentials (ERPs) studies have suggested a possible participation of the visual cortex of the blind subjects were asked to discriminate 100 couple Farsi words (auditory discrimination tack) while they were listening them from recorded tape.The results showed that the blinds were able to discriminate heard material better than sighted subjects. (Prro.05)According to this study in blind subjects conical are as normally reserved for vision may be activated by other sensory modalities.This is in accordance with previous studies. We suggest that auditory cortex expands in blind humans.

Rehabilitation of deaf individual is one of the important subjects that has attracted attention of many researchers during past centuries. Different opinions have been established in this direction. Electrophysiologic tests were established and developed parallel to developments in rehabilitation. Therefore, opinion of using electrophysiologic test for evaluation and fitting of hearing aid became gradually popular. Ultimately, the electrophysiologic tests are used in evaluation and fitting of hearing aid in two ways:1-Direct way2- Indirect wayIn direct way aided ABR is obtained and special attention is paid to wave V. This technique has many difficulties. Inindirect way, electrophysiologic tests such, ECochG, OAE and ABR, AMLR, ALR and P300 and other objective tests are used, especially in infants and neonates for evaluating the state of hearing. Researches are continuing in this field. It is probable to have aided electrophysiologic responses with speech stimuli in near future.

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.

Auditory integration training (AIT) is a hearing enhancement training process for sensory input anomalies found in individuals with autism, attention deficit hyperactive disorder, dyslexia, hyperactivity, learning disability, language impairments, pervasive developmental disorder, central auditory processing disorder, attention deficit disorder, depressin, and hyperacute hearing. AIT, recently introduced in the United States, and has received much notice of late following the release of The Sound of a Moracle, by Annabel Stehli. In her book, Mrs. Stehli describes before and after auditory integration training experiences with her daughter, who was diagnosed at age four as having autism.

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.

Neurofibromatosis type 2 (NF2) is an inherited disease which is mainly characterized by the development of multiple schwannomas and meningiomas.  Incidence of the disease is about 1 in 60,000. Affected individuals inevitably develop schwannomas, typically affecting both auditory-vestibular nerve which lead in hearing loss and deafness. The majority of patients present with hearing loss, which is usually unilateral at onset and may be accompanied or preceded by tinnitus. Vestibular schwannomas may also cause dizziness or imbalance as a first symptom. Nausea, vomiting or true vertigo are rare symptoms, except in late-stage disease. NF II is caused by a defect in the gene that normally gives rise to a product called Merlin or Schwannomin, located on chromosome 22. Diagnosis is based on clinical and neuroimaging studies. Presymptomatic genetic testing is an integral part of the management of NF2 families. Prenatal diagnosis and pre-implantation genetic diagnosis is possible.

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.