There are increasing evidences about the vestibular damage caused by the exposure to noise. Histological and functional derangements of the vestibular system have been reported in laboratory animals exposed to high levels of noise. However, clinical series describe contradictory results with regard to vestibular disturbances in industrial workers and military personnel suffering from noise induced hearing loss (NIHL). Animal studies have proved that crista ampullaris bears the most disturbances, though some damages have been also detected in macula of the utricle and saccule and utricle. These changes have been induced due to acoustical pressure on the vestibular labyrinth. The findings from the experiments regarding vestibular function in patients suffering NIHL have shown a paramount diminish in vestibulo-occular Reflex (VOR). The correlation among NIHL, VOR and unilateral caloric weakness were statistically significant which can be due to a common mechanism of disturbances in the function of cochlea and vestibule.

NIHL occurs when too much sound intensity is transmitted into and through the auditory system and can be occur following a shot gun or the exposure to a moderately intense sound for a long period of time. NIHL caused by acoustic trauma refers to permanent cochlear damage from a one-time exposure to excessive sound pressure. This form of NIHL commonly results from exposure to high-intensity sounds such as explosions, gunfire, a large drum hit loudly and firecrackers.Meanwhile the sound intensity, duration of exposure and personal hearing thresholds as the effective factors in the amount of noise induced hearing loss should not be overlooked.  Since numerous investigations have been performed about intense sudden sound we will discuss it in detail in the current article.

Many researchers have reported that after the sound trauma, RNA and DNA in the outer hair cells and ganglion cells will decrease. Some scientists have also mentioned the mitochondrial enzyme deficits in cochlear cells. Sound stimulation will induce the decrease of enzyme activities which are effective in the process of energy production. This process happens because of the reduced ATP synthesis and in turn the damage to receptors due to energy disruption.  The moderate oxygen deficiency can also be considered as a potential factor in the amplitude changes of the potential of cochlear microphonic due to irrita6ing sounds. On the other hand, since the organ of corti is far from blood tissue, logically, Anaerobic Glycogen should be considered as the main factor in the metabolism of the organ of corti.In addition to that, there are evidences which demonstrate intense acoustical stimulation can increase Na+ and decrease K+ in endolymphatic fluid and a contrary effect in perylimphatic fluid in scala vestibule.

Sounds are the creatures of God which are found in nature in diverse forms. In addition to sounds naturally exist in the environment there are artificial sounds that is hand-maid and we experience them in our daily life. Industrialization has had detrimental effect on manufacturing such sounds in the environment which in turn can affect our mental and physical state.The current article is taking sound from a religious point of view into account. We want to discuss the role of sounds in perceiving the meanings of related concepts and also will have an overall look on the devastating effects of noise and irritating sounds on human life and the human mental and physical health.

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.

The human immunodeficiency virus (HIV) is the virus that causes AIDS (acquired immune-deficiency syndrome). Head and neck are the most common sites in contamination with this virus. HIV can affect outer, middle and inner parts of the ear. Changing in the color of the skin, effusion, infection and sudden hearing loss are some types of the audiological and ontological findings in such patients.

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In this study, we tried to put forward some formulas for interpreting Alternate Binaural Loudness Balance (ABLB) test results by using characteristics of ABLB graphs. Last step of loudness balancing (in dB HL) and thresholds of both ears are considered as formulas variables. The procedure includes: At first, resulting values are put in a formula to obtain type of graph slope. If the slope represents different recruitment (complete, partial or hyper recruitment), the second formula (last test step value ratio) will be used to determine recruitment types. It should be mentioned that in determining exact ABLB test results, ± 10 dB variability must be considered as a test error. As a result, mentioned formulas have not been an exception and this error factor was included in computing them. In next step, we tried to reduce test time which may be considered as a dilemma for test by using this method. Therefore, the test includes only the last step of loudness balancing and the mentioned formulas are used to obtain the test results. At last, the results of this method were compared to the graph procedure for determining their effectiveness.

Recent studies have been ocused on designing an intelligent system containing binaural fitting. Researchers are mostly aimed at seperating signals from background noise and other disturbing signals. most of such techniques include Digital Signal Processing(DSP). Here we will have a look in this technique.

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.

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.

One of the most important issue for selecting and fitting of hearing aids that should receive special attention is binaural amplification.According to several investigations, superiority of binaural amplification on monaural one is confirmed.Binaural Amplification may have considerable effects on fromation and developing of superior dimensions of hearing including: Localization, Binaural squelch (Better hearing in presence of noise).So, it is necessary to know the basic and scientific concepts and applicable principles of binaural hearing and binaural fitting.Present paper deals with this important subject.

In order to develop oral communication, hearing impaired infants and young children must be able to hear speech comfortably and consistently. To day children with all degrees of hearing loss may be condidates for some kinds of amlification.As children differ from adults, many Factors should be consider in hearing aid selection, evaluation and fitting. For example the child age when he or she is candidate for custom instruments? Do we consider programmable Hearing aid? Are multi memory instruments appropriate for them? What about directional microphones? What style of hearing aid do we select? In this paper such questions are responded.

OAEs are sound founds in the external aditory meatus that originate in the cochlea. OAEs are generated only when the organ of corti is in near normal condition and They can be detected only when the middle ear system is operating normally. The sound generated by the cochlea are small but  potentially audible, sometimes as much as 30 dBSPL. They can emerge spontaneously in the cochlea, but more commonly OAEs follow acoustic stimulation. No electrod are needed to  observe OAEs. In fact, microphone are used to detect them.

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.

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.

Auditory Hallucination or Paracusia is a form of hallucination that involves perceiving sounds without auditory stimulus. A common is hearing one or more talking voices which is associated with psychotic disorders such as schizophrenia or mania. Hallucination, itself, is the most common feature of perceiving the wrong stimulus or to the better word perception of the absence stimulus.Here we will discuss four definitions of hallucinations:1. Perceiving of a stimulus without the presence of any subject2. hallucination proper which are the wrong perceptions that are not the falsification of real perception, Although manifest as a new subject and happen along with and synchronously with a real perception3. hallucination is an out-of-body perception which has no accordance with a real subject In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid, substantial, and located in external objective space. We are going to discuss it in details here.