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.

Diagnostic ultrasound is a beneficial technique which can be used the audiologists based on essential instruction. Although there are a lot of barriers in relation to the size of the probe and the resolution of the pictures which are obtained,with this method some kind of information can be gained that is impossible to get by any other method. The ability of real- time A and B modes for direct visualization makes them useful tools to study the changes of the ear structures. Ultrasound system is a useful method to evaluate dizzy patients, which can be potentially used along with vestibular tests.

Clinical picture of vestibulotoxicity with drugs includes imbalance and babbingoscillopsia. Nistagmus is not seen and thermal and rotational tests show bilateral dysfunction of labyrinths. Aminoglycosides are the main category causes inner ear toxicity more than any other antibiotics.The amount of degeneration of vestibular system depends on the type of drug, repetition and total dose age.

Hearing function can affect communication skills and especially speech and language abilities.As a result, most of the attempts in behavioral audiometry have focused on the improvement and rectification of the techniques for hearing evaluations of the infants and children.Crib-O-gram and the methods suggested by northern & Downs are some of the mentined protocoles.

For years a significant advance for evaluating hearing sensitivity of children have been taken place. say, behavoral visual audiometry, VRA, TROCA and play audiometry. some studies also have been performed regarding to the use of BOA technique in mental retarded children and its success in evaluating hearing sensitivity in such children.other protocoles use rewarding thechniques for reinforcing child's responses which have been demonstrated to be success in the evaluation.

In addition,by comparying the results of frequency and intensity discrimination (by means of Luescher test), the changes in the resonance frequency of the outer ear and loudness conmfortable level(LDL), one can study the process of hearing development in children.

It has always been attempted that systems connected to the ear through hearing aids efficiently meet the patient expectations. It is recommended to avoid using occluded earmolds when the hearing is normal or there is mild hearing loss. In order that natural sound  reaches to the ear, the ear canal should stay open as much as possible.To achieve the above goal and the suitable acoustic modifications, non-occluding ear molds are beneficial.

Hearing aid selection as the first step in modifying the hearing loss is a critical point . people with severe to profound hearing loss need special consideration. In order to determine the amount of gain and output of hearing aids, some formulae are presented. Although most of these formulae are planned for mild to moderate hearing loss, they are used for severe to profound hearing losses. POGO method is one of these formulae.This method, based on halving the hearing threshold, is not suitable for profound hearing loss. There are some considerations in revising this method for severe to profound hearing loss and it’s name has changed to POGO II, too.

 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.

People with profound hearing loss are not able to use some kinds of conventional amplifiers due to the nature of their loss . In these people, hearing sense is stimulated only when the auditory nerve is activated via electrical stimulation. This stimulation is possible through cochlear implant. In fact, for the deaf people who have good mental health and can not use surgical and medical treatment and also can not benefit from air and bone conduction hearing aids, this device is used if they have normal central auditory system. The basic parts of the device included: Microphone, speech processor, transmitter,  stimulator and receiver, and electrode array.

The study included 80 patients treated for sudden deafness over the last 5-7 years. Case history, laboratory findings, pure-tone audiogram and electronystagmography (ENG) findings were noted. If any abnormalities had been recorded in ENG studies, the studies were redone. ORL status was redefined and audiograms were obtained in all patients. When becoming ill, the 80 patients had not differed from the normal population in common cardiovascular risk factors. None of them had had signs of viral infection (paired serum samples had been taken at 2-week intervals routine examinations had been done for common viral antigens). As many as 31 of the 80 patients with acute hearing loss had had abnormalities such as spontaneous nystagmus (PN), hypoexcitability (HE) and directional preponderance (DP) in the bithermal caloric tests (+44 degrees C, + 30 degrees C) of their ENG studies. Twenty of the 31 patients still had abnormal ENG studies after 5-7 years. Only 1 subject had positional nystagmus, and none had subjective vertigo. Patients with an abnormal ENG study showed a poor recovery of the speech reception threshold, whereas those with a normal ENG study showed slightly significant (p less than 0.05) recovery.

Diagnostic ultrasound is a beneficial technique which can be used the audiologists based on essential instruction. Although there are a lot of barriers in relation to the size of the probe and the resolution of the pictures which are obtained, with this method some kind of information can be gained that is impossible to get by any other method. The ability of real- time A and B modes for direct visualization makes them useful tools to study the changes of the ear structures. Ultrasound system is a useful method to evaluate dizzy patients, which can be potentially used along with vestibular tests.

Hearing function can affect communication skills and especially speech and language abilities.As a result, most of the attempts in behavioral audiometry have focused on the improvement and rectification of the techniques for hearing evaluations of the infants and children.Crib-O-gram and the methods suggested by northern & Downs are some of the mentioned protocols.For years a significant advance for evaluating hearing sensitivity of children have been taken place. say, behavioral visual audiometry, VRA, TROCA and play audiometry. some studies also have been performed regarding to the use of BOA technique in mental retarded children and its success in evaluating hearing sensitivity in such children.other protocols use rewarding techniques for reinforcing child's responses which have been demonstrated to be success in the evaluation.In addition,by comparing the results of frequency and intensity discrimination (by means of Luescher test), the changes in the resonance frequency of the outer ear and loudness comfortable level(LDL), one can study the process of hearing development in children.

In the current article we will have a look at the evolution of audiological tests. Based on the Olsen's theory, having knowledge about the history of audiological evaluation is not a 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 investigators should not be ignored.

 This is a study performed following the study between the years 1980 to 1982 to investigate risk factors and diagnostic and rehabilitative patterns in a group of newborns suffered hearing loss in a city centre. The current findings which have been attained from 1983 to 1988 manifested that just one third of the deaf newborns can be tracked by means of common auditory evaluation tests in the Neonatal Intense Care Unit (NICU). Although these newborns have been followed sooner than the infants in the Well Baby Nursery (WBN). The age for enrolling in the Parent-Infant Program for both groups is approximately 20 month. During these 8 years it has been detected that the common age for taking part in the rehabilitative programs for newborns is 1 year or more greater than that recommended by Joint Committee on infant hearing

 People with profound hearing loss are not able to use some kinds of conventional amplifiers due to the nature of their loss. In these people, hearing sense is stimulated only when the auditory nerve is activated via electrical stimulation. This stimulation is possible through cochlear implant. In fact, for the deaf people who have good mental health and can not use surgical and medical treatment and also can not benefit from air and bone conduction hearing aids, this device is used if they have normal central auditory system. The basic parts of the device included: Microphone, speech processor, transmitter,  stimulator and receiver, and electrode array.

Sudden hearing loss is a type of hearing loss that occurs in three successive frequencies by more than 30 dB and in less than 72 hours. Every 10 person in 100000 in the world and 25000 people in USA suffer this kind of hearing loss. The average age of the onset is 43 years old.

The corpus callosum is a group of nerve fibers that connect both sides of the brain and allow them to communicate. In the current article we are aimed at discussing the special functions of each hemisphere and the role that corpus callosum plays in many cognitive functions that will led in the interaction of the operations of the hemispheres. Corpus callosectomy can affects hearing abilities and other communicative functions.

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.