Material and method: by using a dosimeter we tried to study the amount of noise exposure each worker is exposed to the microphone was connected to the collar of the shirts and the dosimeter to the belt. The audiometric evaluations were performed before starting work in the factory.
Results: the years of experience in the factory has a significant correlation with amount of hearing loss in the workers of the noisy environments (based on the findings of the dosimetric measurements)
Conclusion: the findings of the current study demonstrated that workers of the door and window construction factory were exposed to high level of noises and their hearing thresholds were largely affected by the noise pollution. This is in accordance with results of the similar studies. This impact was mostly revealed in the forgers.

Sound is an inseparable part of human life and provides us with lovely experiences such as listening to music. Musicians from classical orchestras to rock groups are exposed to high decibel of sounds. Musicians playing percussion musical instruments are exposed to high level of impact noise and players of Brass musical instruments are highly exposed to noise peaks higher than 100dB. Woodwind players are enduring the risk of posing directly in front of Brass players. Based on the above-mentioned risks for hearing loss clinical consideration of noise induced hearing loss in musicians is highly required.In the current study we were aimed at examining hearing stratus of classic and traditional musicians by means of pure tone audiometry in Islamic Republic of Iran Broadcasting. 33 subjects were evaluated aged between 22 to 59 years old. Their musical experience was variable between 6 to 45 years.The study demonstrated that most of the musicians in this study suffered bilateral high frequency hearing loss with a notch in the frequency range of 4-8 KHz.

Introduction: We estimated the noise in an industrial shoe factory to determine the effect of noise in the workplace on the hearing status of the workers in such environments.
Materials and method: the intensity of noise in dB in different parts of the factory was estimated. Then working people in each part was selected randomly and their hearing thresholds were evaluated by Conventional audiometry.
Results: The results demonstrated that 23% were required to estimate thresholds more precisely and 95 needed close examination by Otolaryngologist. Besides, 10% of the workers suffered sensory neural hearing loss whose 2% of them diagnosed as NIHL.
Discussion: Since the mentioned factory has good hearing conservation program for the workers, it seems that promoting the program can decline the number of noise induced hearing losses to the least numbers.

In the current investigation we gathered information about the hearing thresholds, types of hearing loss, types of tinnitus, and also the prescribed tinnitus maskers for the veterans. We were aimed at determining the percentage of tinnitus, audiogram shape and its relationship with tinnitus, and the percentages of veterans using tinnitus maskers. The needed information was prepared by studying the audiograms and file of the patients.  The results of the investigation have been prepared here in details.

Background: workers in the spinning company were audiologically evaluated to estimate the impact of industrial noise of the factory on their hearing status.
Material & Method: subjects were 185 workers of the spinning post in the first flat of yarn. Hearing thresholds were compared at the beginning of their employment and after 1 to 19 years of work experience.
Results: the percent of hearing deficit was lower than the data reported by WHO.
Discussion: efficient application of hearing conservation devices has had a remarkable effect on hearing status of workers.

Background: Many Endogenic and exogenic factors can affect the individual&aposs susceptibility to noise exposure, for instance middle and outer ear characteristics, the amount of oxygen transmission, skin color, medical history, mental state and the patient&aposs attention, age, cigarette smoking and many otjher factors affect the amount of noise induced hearing loss and acoustic trauma.The current study was aimed at investigate the impact of various Endogenic and exogenic factors on the amount of PTS and TTS in veterans in Hamedan province.
Results: The results of the study manifested that:- Veterans with tinnitus suffered more hearing loss than patients without this symptom.- Extended intensity of noise and exposure time to war noises can exacerbate the amount of hearing loss in veterans who had fight more.- The degree of hearing loss in patients who had previously suffered middle ear infections or otitis or the familial history of hearing loss was more than people without such history
Discussion: The findings of our study in compatible with the results of other similar studies and confirms the effect of different pathologic and non-pathologic factors on the degree of noise induced hearing loss.

As the industry develops in the societies, human being is more likely to exposed to high level of noises and be at risk of hearing loss. Urbanism and working in the situation which are not in accordance with the personal nature make people even more susceptible to risk factors of hearing loss.   Exposure of workers to industrial noise has been the subject to several studies and it seems that reconsidering the situations in both society and nature can be a key to change environment for decreasing noise in the society.For example in Tehran, geographically, the slope of the earth from north to south is 5-10% which is a main factor contributing in noise pollution.Moreover, the source of most outdoor noise worldwide is mainly construction and transportation systems including motor vehicles, air craft noises and rail noises. Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area.In the current article we have examined both conditions in the hearing condition of workers with high levels of noise exposure.

Workers in the Municipality of Tehran expose to high level of noises. The major sources of noise are the vehicles for garbage collection, Asphalt production and its usage in construction of pavements, Repairing motor vehicles, technical and constructive implementation including road and building construction , Forging, Concrete planning, Welding, Building structure and  etc.Although most of such activities are performed by Contractors, many workers are exposed to high levels of noise during such processes. Since hearing conservation program is a duty for the Municipality, we have managed to use some new protocols to prepare a convenient and quiet environment for workers that is going to be discussed here in the present article

We designed this study to measure the Percussion caused by pneumatic drill( 32gram) which is used commonly in different in city services. this study have been performed in the summer of 1375 in Hamedan. The results demonstrated that the average background noise level (including environment and compressor) was 92.4 with standard deviation of 5.4 dBC, the average background noise level of the drills while working was 109.6 dBC with the standard deviation of about 2.2dBC and the average peaking factor was 18.6 with a standard deviation of 3.7dBC. the average background noise level of the drills while working in a distance of 5m, 10m and 20m from the source respectively were 98.6 dBA(with a standard deviation of 2.8dBA), 91.5dBA(with a standard deviation of2.6dBA) and 86.8dBA with a standard deviation of 2.8dBA).Based on the obtained results and the potential effects of exposure to noise which mainly can be summarized to damage to auditory system, interference with the communication skills, neural excitation, Hypertension and tachycardia the side effects of noise should be taken in to account seriously.Based on the mounting evidences regarding the adverse impact of working in the noisy environment and the damaging consequences of living in such atmospheres and the findings of the current study which confirms that the noise exposure level is more than allowed limit, the health of the workers and citizens is threaded by the noise pollution factors mentioned in the current study and serious considerations should be taken in to account.

We measured the noise caused by Vehicles and its subjective effects in the Modarres high way In Tehran. we examined 143 cases in 11 stations in the mentioned pathway with an accuracy of 95%  and a standard deviation of 39%. The noise criteria of Leq and the number of vehicles were determined in dBA. The loudness contours were also measured in some stations to determine the subjective impacts of noise. Then the correlation of the responses of the interviewees with sound pressure level was measured. Based on our findings, decrease of  the noise of traffic sources should be considered three levels: the first level is noise reduction at the level of source, e.g. the vehiclesthe second is Noise reduction at the traffic level and the third is noise reduction at the level of general activity.

This study was designed to measure the noise caused by a 63.20KV transformer in the residential area close to it that consisted of 36 points inside the post and the surrounding area around it (including 29 points+30 points). the results demonstrated that noise caused by the function of the transformer t1 was 59.1dBA with the standard deviation of 6.89dBA and for transformer t2 was 59.89dBA with a standard deviation of 6.86dBA .The measured noise in the west residential area around the post was 54.95dBA with a standard deviation of 1.76dBA, in the east was 54.1dBA with a standard deviation of 2.52dBA and in the south was 49.71dBA with a standard deviation of 1.07dBA.The statistical measurements showed no significant difference in the measured noise around in the mentioned direction.The results of this measurements manifested that the noise measured in all residential areas close to the post was more than noise permitted in night.

Tinnitus from the Latin word tinnire meaning ringing is the perception of sound within the human ear in the absence of corresponding external sound. The most common cause is noise induced hearing loss. Tinnitus may be induced by an acoustic trauma or a permanent noise in the workplace. In case that Tinnitus is induced by acoustic trauma the site of lesion is commonly the base of the cochlea. Tinnitus in the senile population is mostly accompanying presbycusis. Although the incidence of permanent tinnitus following noise exposure is high, little is published about this issue. In the current article we are aimed at studying the prevalence of tinnitus in Minoo and other manufactures.

One of the most common and important sources of noise in the residential environments are vehicles such as airplanes and subways. Trafficking of vehicles in streets and highways, psychologically, have damaging impacts on people living close to such areas. The development and expansion of the trading and industrial units is another factor that causes more and more exposure to noise.We have aimed at measuring the noises caused by vibration of subways of the Line of Karaj-Tehran-Mehrshahr and its effect on its surrounding area.To study this effect we designed a mathematical model and put the information of this subway line in the mentioned model. Then we analyzed the findings.This model demonstrated that we can control the harsh noise of the subway by reducing the speed of the train to 60Km/h in some points and increase in other parts to 130Km/h.

Nowadays, unwanted noise is present everywhere in the workplace and in the living environment and disturbs human peace and calm. In spite of the importance of the indirect impact of noise on human life, little is performed about this issue in our country. Therefore, the present study have been focused on the measurement of noise pollution that impose operators of the telecommunication company in addition to the evaluation of the psychological and mental effect of sound on the telecommunication operators.

Nowadays, sound is a critical part of our daily life and its unwanted and undesirable disturbances in the environment and in the workplace has induced much psychological and physical annoyance to human being and had also lessened the efficacy of the daily activities. Since the mechanical vibrations of molecules in the air had led in producing sound and considering profound damaging vibrations produced by the harsh sounds in the objects and instruments, we have studied the noise and the vibrations caused by it, together.With this introduction and Considering the potential devastating impact of noise and the need to keep staff which are working in the control room secure from this effects the power house of "Shahjid Madhaj"  have proposed a project to control and limiting the noise in the control room by examining the diverse ways of transmitting sound into it. The project will be discussed here in details.

Noise measurement and social questionnaire surveys in three residential areas around Mehrabad International Airport (Tehran, Iran) were based upon randomly selected dwellings in each area. A total of 193 individuals responded and many are annoyed and dissatisfied with aircraft noise and in consequence they would like to move. Aircraft noise is the strongest negative environmental factor affecting the residents in the vicinity of Mehrabad Airport and it could be a hazard for their health.

Materials and Methods: It is for the first time in Iran that designing and construction of phase-shifter instrument for performing Masking Level Difference have been studied. For reducing limitations of MLD test in middle ear pathologies, new methods of performing MLD has been considered.
In this method noise is conducted by bone vibrator, located on forehead. The comparison between standard method and proposed method has been obtained.Forty 20-25 year-old men referring to the Faculty of Rehabilitation Science in Iran university of Medical Sciences have been tested in the period of time between 10.30.1998 to 12.21.1998.The MLD test was performed in both method at frequencies of 250, 500, 1000, 2000 & 4000 Hz.
Results: The mean of MLD results n the standard method was 11.175 dB ranging from 10 to 13 dB that is in accordance with normative data.
- There was no significant difference between the means obtained in the methods for performing MLD.
- In both methods the MLD means decreased with frequency increments.
Conclusion: It is preferable to use proposal method in middle ear disorders due to normal cochlear sensitivity and subsequently enough noise that is conducted by bone conduction (60 dB SPL).

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.

Objectives :Determining the frequency distribution of hearing disorders among the student of public elementary school by Otoscopy, Puretone Audiometry, impedance Audiometry and questionnaires.
Methods and Materials: This study was can-led out in a cross - sectional descriptive survey - on 1000 students (500 girls and 500 boys) among the student of primary school of EslamAhad Gharh, academic year 1376-77
Results: 1- Otoscopy examination abnormal conditions of external ear canal was found in 13.65% of cases mostly impacted ceruman (13.3%). Abnormal conditions of external ear canal was more prevalent in girls than boys and the difference was statistically meaningful in the right (P V=0 .012) and left (PV=0.043) ear. Abnormal tympanic membrane was seen in 6.75% of cases mostly retraction (295%).
2- Impedance Audiometry: 11.05% abnormal tympanograms were observed, mostly type C (4.1%).
3- Pure Tone Audiometry: An overall 9.7% hearing loss was found in this population including 3.5% bilateral and
6.2% unilateral hearing loss. 4.15% of population suffered from SNHL observed mostly in boys and conductive. Hearing loss mostly in girls and the difference was statistically meaning in the left ear (PV=0.03).25.8% of cases were in need of medical care and surgery and six of them (l.e 0.6%) were in need of rehabilitation services.Family background showed on effects on the hearing disorders.Only 11. 4% of parents, 13.4% of teachers and 14.4% of afflicted students were aware of the problem.

Objectives: determining the frequency distribution of hearing disorders among the student of public elementary school by Otoscopy, Puretone Audiometry, Impedance Audiometiy and questionnaires.
Methods and Materials:This study was carried out in a cross - sectional descriptive survey - on 1200 students (600 girls and 600 boys) among the student of primary school of Neishabbor, academic year 1376-77
Results:1- Otoscopy examination abnormal conditions of external ear canal was found in 14.1% of cases mostly impacted ceruman (13.6%) Abnormal conditions of tympanic membrane (0.4%) and foreign body 0.16%. Abnormal conditions of external ear canal was statistically unmeaningful. (P V=0 .8)
2- Impedance Audiometiy: 5. 75% Abnormal tympanograms were observed, mostly type C (3.15%)
3- Pure Tone Audiometry: An overall 5.5% hearing loss was found in this population including 3% bilateral and 1.25% unilateral hearing loss. Only conductive hearing loss was found in this population (2.7% in right ear and 3.5% in left ear), PV=0.9.Hearing loss observed mostly in girls but the difference was slight.Family background showed no effects on the hearing disorders.9.8% of cases were in need of medical care and 0.3% were in need of rehabilitation services.Only 28.8% of parents, 36.3% of teachers and 40.9% of afflicted students were aware of the problem.