Air conditioning systems are used in industries and residential environments with the aim of improving environmental conditions and creating a comfortable temperature for users. Considering the production of Sound and vibration in most of its components, the lack of control of the production Sound level always exposes the users to unwanted Sound, which in addition to hearing complications, also causes fatigue and dissatisfaction with the environmental conditions. . Compressors are one of the most important sources of Sound production in air conditioning systems, and screw compressors are one of the most widely used in air conditioning industries. Therefore, the compressor shell should be designed to minimize the transmission of Sound from inside to outside. Since the maximum working temperature of compressors is up to 80 degrees Celsius, therefore, in this research, an acoustic test was performed on a sample of a screw compressor shell in two modes of ambient temperature and maximum working temperature inside the acoustic room, and the effect of temperature increase on the Sound pressure level. transferred from the shell to the external environment is discussed. Finally, based on the frequency analysis performed in two conditions of ambient temperature and maximum working temperature and comparing the amount of Sound transmitted to the environment at different frequencies, practical solutions to reduce the amount of transmitted Sound pressure have been presented.

Low-frequency noise is annoying even at lower levels and affects cognitive functions of individuals. Some individual differences, such as sensitivity, can reduce or increase the effects of noise on cognitive performance. This study investigated the effect of noise sensitivity on cognitive performance in the presence of low-frequency noise. In this experimental study, 120 fourth-year seniors in the field of health sciences year from Hamadan University of Medical Sciences, Iran were selected through purposive sampling (60 students with high sensitivity and 60 students with low sensitivity). All the participants were exposed for 40 min to the noise levels of 50, 60, and 70 dB at the frequencies of 125 and 250 Hz, during which, the cognitive performance of the subjects was examined using the Integrative Visual-Auditory Continuous Performance Test (IVA CPT). Data were analyzed by independent t-test, and ANOVA test in SPSS 20. 0 software. The low-frequency noise negatively affected the components of cognitive performance so that with increasing the Sound pressure level (SPL) from 50 to 70 dB and from 125 to 250 Hz (P<0. 05), the components of cognitive performance decreased. The results also showed that in female subjects with high sensitivity, cognitive performance components were more affected than the male subjects with low sensitivity (P<0. 05). The components of attention and work quality reduced with increasing SPL, and this negative effect of low-frequency noise was higher in women with high sensitivity.

Workplace factors such as Sound must have the minimum impact on the operators of combine harvester, so that they can guide and control many functions of the combine. In this study, some factors affecting the noise generated by two combine harvesters John Deere 1055 and Sampo 3065 were evaluated. Research factors were engine speed, gear ratios, type of operation and microphone distance. The results of this study indicated that Sound pressure level decreased with increasing center frequencies. The Sound pressure level of John Deere and Sampo combine at center frequency of 4000 Hz were 87.96 and 84.73 db, respectively. The results showed also that the maximum Sound pressure of John Deere and Sampo combines were116db at frequency of 250 Hz and 111.1db at frequency of 40 Hz, respectively.

Background: Noise, is one of the most common sources of occupational diseases, which has a physical nature studied in various forms. Since few studies have been conducted on some of these forms, such as the calculation of Sound spectrum level, the present study was done to assess the balance of spectrum in Crepenaz textile factory.Methods: In this study, first, Pykanol Hall in Crepenaz factory, which is the most important location in terms of noise production, was set up into 286 Sound stations with 6 in 6 meters wide for each one. In addition, noise levels have also been studied. The Sound pressure is measured using a Sound level meter and subsequently frequency analysis was performed in the stations with the level of noise more than 85 dB. In the third step, with calculation of the balance of spectrum in these stations, an opportunity was provided to facilitate the comparison of the extent of the risk exposure in the stations.Results: Of 286 Sound stations, only 73 were active. In seven stations, the Sound pressure level was more than 85 dB. A comparison between Sound levels was subsequently provided and carried out.Conclusion: The present study demonstrated a distribution of Sound pressure levels in the different parts of the factory. The Sound control in this work place was provided through determining the stations with high Sound levels and calculating the Sound levels.

Background: One of the harmful factors in the field of occupational health is exposure to noise and vibration. Better control of hazardous agent requires robust and efficient software that prevents the increased risk with real-time control. Therefore, this study was conducted with the aim of setting a system using labview software to monitor the Sound momently.Methods: The research is an experimental study that was doing by using Labview software, microphones and Sound analyzer card. Environmental information collected as Sound pressure level via microphones and then processed by the Sound analyzes card. The information showed by software as a graph or plot in the next step.Findings: This software is including the front panel, back panel and connector panel that with these panels can be determined information such as various frequency weighting and time weighing. After entering the information, can be specified the Sound pressure level, Sound amplitude, power spectrum, power spectral density and other Sound characteristics.Conclusion: Labview programming capabilities in the field of Sound can be referred to the measurement of Sound, frequency analysis and Sound control that actually the software acts like a Sound level meter and Sound analyzer. According to the mentioned features, you can use this software to analyze and process Sound and vibration as a monitoring system.

Noise is an unwelcome harmful factor in hospital environments. This study was conducted aiming at evaluating Sound pressure levels in different parts of an educational hospital, the knowledge of that hospital’ s personnel over Sound pressure level, and their attitude towards it. In this cross-sectional study, the knowledge of 29 doctors, 63 nurses, 58 clerks, and 25 orderlies was checked. All questionnaires were distributed among the personnel through simple random method, after determining the reliability and validity of them. Sound pressure level was measured by Cell 450 Sound meter of the UK from the height of 150 cm, and the gathered data were analyzed by Chi-square test and SPSS software. The results of the present study indicated that, there is a meaningful relationship between job rank of an individual and Sound knowledge grade of the same person (P< 0. 05), but the relationship between the job rank of a person and his attitude score was proven to be meaningless. Measurement findings after data analysis showed that, Sound pressure levels and Sound interference levels in all the studied parts were higher than the recommended limits in hospitals, and average Sound levels of the hospital in different parts of it equaled 56. 3 decibels (dB). Gaining knowledge over Sound/ noise effects, improving the personnel’ s attitude towards this subject, and regulations observance could be influential in work environments.

Background and aims: The ceramics industry is one of the key industries in the economic development of any country. This industry has a large share of Iran's non-oil exports so that in recent years it has consistently placed Iran's position in the production and export of this product among other developing countries. However, there are many harmful factors in these industries, which threaten the physical and mental health of workers, the most important of which are environmental hazards, cooling, heating, vibration, noise pollution, and so on. Noise pollution is very important in the ceramics industry, as in other industries. According to research, about 600 million people worldwide and 30 million people in the United States face more than 85 dB noise in their workplace. According to the report, about 2 million workers are reported in Iran, according to a report by the Health Ministry's Workplace Health Center. Also, according to the National Institute of Occupational Safety and Health (NIOSH), 14 percent of the total workforce is working in environments with noise levels above 90 dB. Consequently, exposure to noise in the world, including Iran, is a problem in the workplace. In addition, according to studies in the ceramics industry, it can be concluded that exposure to noise is high for the employees of the industry so that the study results Kargar et al. Found that about 45% of the ceramic industry's employees are exposed to noise above the permitted level. As a result, personal exposure to noise will be of particular importance to employees in the industry, based on the results of past exposure research. Hair can work with noise in the workplace, except for hearing loss Hypertension, cardiovascular disease, gastrointestinal, behavioral, mental and sleep disorders. On the other hand, acoustic disturbance is a new topic that has been considered by researchers recently as one of the negative effects on one's health and comfort. The most common subjective response is measurable, and its effects may include physiological responses, central nervous system responses, and biochemical changes. These failures include various areas such as memory, distraction, forgetfulness, inadvertent errors. Also, due to interference with daily activities can cause serious harm to the person. As a result, the present study investigated acoustic annoyance as the most common measurable subjective response among people exposed to noise and cognitive impairment as an indicator of one's ability to perform tasks that he or she is naturally capable of performing in a ceramic industry. At the same time, it is intended to examine the relationship between Sound pressure level values ​ ​ with acoustic annoyance scores and cognitive failure. Methods: This descriptive-analytical study was conducted in the ceramics industry in 1998. To determine individual exposure to noise, we first examined the production sections and the annual results of the Sound measurements, and then the loudspeakers were identified. In this study, the sample size was calculated using Cohen's sampling formula with 80% confidence interval of 95% confidence level of 96 persons. Under 50 years of age, congenital hearing impairment, lack of sleep medications and CNS overdose, depression, and lack of a second job were considered. Thus, at the end of this study, after eliminating some of the study population, 50 workers were exposed and 50 administrative staff were placed in the control group. Also, volunteers were asked about the importance of the research subject. Then, to complete the questionnaires used in the study, a research session was held with the presence of the research population. Then the questionnaires were distributed to the individuals and their observation was completed. given. DOS 1354 TES was used to measure the Sound pressure level. At the same time, the subjects completed a demographic questionnaire, noise annoyance and cognitive impairment (CFQ) questionnaire. Measurement was done in two groups of exposure and control. The TES-1356 calibrator was manufactured in Taiwan to obtain the exact results of the equipment used before each measurement. In accordance with ISO 9612 standard, a dosimeter microphone was installed on their collar at a distance of 10-30 cm from the outer ear canal. At the end, exposure dose calculations were performed, as production workers were exposed to the same noise levels during the shift, and a two-hour dosimetry was performed and generalized to the equivalent of the 8-hour balance calculations. There are four components that have the first component of distraction (2 items), memory problems (7 items), inadvertent errors (7 items), lack of recall of names (2 items). The acoustic annoyance questionnaire consists of three parts. These three sections include: The first part is heavily rated for workplace noise, the second and third are respectively for workplace noise disturbance and for determining the situations people experience throughout the day, such as fatigue, lethargy, loss of concentration, and so on checked. The questionnaire is divided into 0 to 10 levels of annoyance, with zero being non-annoying and 10 being excessive annoyance. The data were confirmed. Mann-Whitney test was used to analyze marital status with Sound pressure level, acoustic distress and cognitive impairment. In addition, Spearman test was used to correlate the parameters of Sound pressure level, acoustic annoyance and cognitive failure. The level of 0. 05 was considered as the significant level. Results: The results of this study showed that 50% of the study population was 27-33 years old, 45% had a 3 to 5 year work experience, 64% were married and only 9% had university education. Qualitative in both exposure and control groups showed that there was no significant difference between work experience, marital status and education but there was a significant difference in age variable (p <0. 05). Mean Sound pressure levels in the exposure and control groups were 86. 44 86 4. 49 dB and 59. 29 ± 3. 02 dB, respectively. Also the score of acoustic annoyance and cognitive impairment in the exposure group were 70. 79 /10 10. 54 and 63. 46 8 8. 97 and in the control group were 20. 09 20 20. 20 and 45. 14 8 8. 00, respectively. . Also, the highest and the lowest noise pressure levels in the exposure group were 95, 78 dB and 64, 50 dB, respectively. In addition, the highest frequency of acupuncture reported in the case group was 60% in the range of severe distress and 28% in the range of severe distress. However, the highest rate of acoustic annoyance in the control group was 68% in the non-annoyance range and 30% in the mild annoyance range. The results of the analysis of the third part of the acoustic annoyance questionnaire related to the situations that people experience during the day showed that the average experience of fatigue (3. 38), fatigue and drowsiness (3. 40), dizziness (3. 46), Decreased focus strength (3. 58), headache (3. 67), more discomfort (3. 57) than control group. In addition, headaches (3. 67) and fatigue (2. 49) had the highest mean of exposure and control groups, respectively. The results of the statistical analysis showed that there was a significant positive relationship between the scale of acoustic annoyance and mood states (fatigue, lethargy and drowsiness, dizziness, loss of concentration, dizziness, headache, discomfort) (p <0. 05). Also, Kruskal-Wallis test was used to assess the scale of acoustic annoyance with demographic characteristics. The results of Cognitive Failure Survey in the employees of this industry were analyzed in four sections, mean of four sections of distraction, memory problems, inadvertent errors, failure to recall names in exposure group, respectively, 22/01, 20/60, 15/88, respectively. It was 5. 70. However, the mean of the four sections in the control group were reported to be 16. 44, 13. 92, 13. 24, 2. 30, respectively. In addition, the mean correlation coefficient was upward (-0. 778). 0/613) There is a strong association between acoustic annoyance and memory problems and lack of recall. Also, the mean of cognitive failure was analyzed by age, work experience, marital status and education. The results showed that the highest rate of cognitive failure was in the age of 27-33 years, work experience of 5-5 years and cognitive failure in people with Education was also less affected. Also, the relationship between Sound pressure level and cognitive failure criteria showed a positive and significant relationship between them. There was also a significant relationship between Cognitive Failure Scale, acoustic annoyance and Sound pressure level in both the exposure and control groups. r = 0. 768, p <0. 05) showed a significant positive relationship. Conclusion: The results of the present study confirm that the noise level is higher than the recognized limit for hearing and mental health and consequently high levels of noise and cognitive impairment in ceramic workers. The most important outcome of acoustic disturbance in this population is a decrease in concentration, headache, dizziness, lethargy, and drowsiness that affect the physical and mental health of the individual and ultimately the productivity. Sound-induced annoyance followed by experience Emotions such as fatigue and loss of concentration increase the likelihood of human error and sometimes irreparable occupational accidents, which makes clear the importance of noise exposure levels in terms of health and workplace safety. Given the significant relationship between these factors and noise pressure levels, it is recommended to take appropriate measures to reduce workers 'exposure to noise in the industry in order to maintain employees' mental health and increase their work efficiency. Also, considering the individual differences in the sense of distress, assessing people's sensitivity to noise for work in areas with high noise pollution can also help improve workplace conditions and prevent serious injuries in susceptible individuals.

Exposure to noise pollution in closed occupational and non-occupational places can cause disturbances in human well-being, comfort and health. The Sound pressure level index (Lp) inside the building is affected by the Sound power of sources outside and inside the building and the resonance caused by the reflection of the internal surfaces. The amount of Sound energy inside the building caused by these real sources inside and outside the building is determined. In order to determine the effect of internal reflective surfaces as a virtual source of Sound, on the amplification of energy in the closed environment and consequently the amplification of the Sound pressure level, it is necessary to provide models for the prediction of the final Sound pressure level. The existing calculation models show that the control intervention on the internal surfaces of the building through Sound absorbing materials can theoretically reduce the ambient noise up to 30 dB and objectively up to 20 dB. So far, no valid model has been presented to separate the role of the interior surfaces of the building in the amount of Sound amplification of the total of real sources. In this article, while introducing the acoustic analysis indicators inside the building, the room index (RI) is introduced to determine the role of the virtual source in the Sound amplification inside the building, and an experimental model is presented to determine this index.

Background and Objectives: Over the last three decades environmental pollutions became a more noticeable problem in all around of the world. In many countries, noise pollution as a basic problem has a great importance. Development of the city, increasing of industrial centers, increasing vehicles, other annoying noise resources and also little information about the noise pollution of Tabriz city, has led to the doing of this research.Materials and Methods: Sampling and measuring of noise pressure levels was done 180 times According to the EPA standards, measuring was done simultaneously in two stations(commercial-residential areas), three times a day (morning 7:30 -9:30 am, midday 12:30-14:30 pm and night 19:00-21:00 pm) and 30 days in month. Results: Sound pressure level in both stations was higher than the standards and the highest average level with 71.4 db was recorded in Raste-koche station at midday. Also lowest calculated average value with 68.5 db was measured in Golbad station at the morning time that is 8.5 db higher than the standards. Conclusion: Average measured Sound pressure level in two stations was higher than the standards. The results show that Tabriz has a noise pollution in commercial and residential - commercial areas. It is suggested that other noise pollution resources identified and the proper management actions for its reduction be done.