Noise pollution is one of the common physical harmful factors in many work environments.The current study aimed to assess personal and environmental sound pressure level and project the sound-Isosonic map in one of th...Noise pollution is one of the common physical harmful factors in many work environments.The current study aimed to assess personal and environmental sound pressure level and project the sound-Isosonic map in one of the Razavi Khorasan Paste manufacture using Surfer V.14 and Noise at work V.5.0.This cross-sectional,descrip-tive study is analytical that was conducted in 2018 in the Paste factory that contains Canister,production and Brewing unit.Following ISO 9612:2009,Casella Cel-320 was used to measure personal sound pressure level,while CEL-450 sound level meter(manufactured by Casella-Cel,the UK)was employed to assess environmental sound pressure level.Statistical analyzes was done using SPSS V.18 and Linear Regression test.The sound-isosonic maps were projected using Surfer V.14 and Noise at work V.5.0.The results of assessing personal sound pressure level indicated that the highest received dose(172.21%)and personal equivalent sound level(87.36 dBA)were recorded for workers in the Canister unit.According to results of measuring of the environmental sound pressure level,out of 16 measurement stations in this unit,overall 87.5%were regarded as danger and caution areas.The lowest and highest sound pressure levels in this units were 61 dBA and 92 dBA that belong to Brewing and Canister units respectively.Results indicate Over 75%of the Canister and production units had a sound pressure level greater than 85 dBA and these two units were regarded as the most dangerous area in terms of noise pollution.It is there-fore necessary to implement noise control measures,apply hearing protection program and auditory tests among workers in these units.展开更多
Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and impl...Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and implement noise control plans in occupational environments is necessary.Thus,the present study aimed to review environmental sound measurements,drawing of noise maps,and prioritizing the engineering noise control methods using the Analytic Hierarchy Process(AHP).This study was a descriptive-analytical study that aimed to assess occupational noises and present a control plan in the City Gas Stations(CGSs)of Kerman,Iran in 2021.The present study was done in two phases.In the first phase,six CGSs were investigated to measure and evaluate the noise.In addition,the noise map of a CGS was drawn using the Surfer software.Finally,the AHP was used in the second phase of the research to prioritize the control measures.In this phase,four criteria and ten alternatives were identified.According to first phase results,the sound pressure level(SPL)of the stations varied from 76 to 98 dBA.Besides,the majority of the studied stations had a sound level higher than 85 dBA(danger zone).The second phase of the study showed that out of the four evaluated criteria,the executability criterion had the highest impact and the cost criterion had the lowest impact on the selection of control measures with a weight of 0.587 and 0.052,respectively.Based on the results of prioritization of the alternatives,using a silenced regulator(weight of 0.223)and increasing the thickness of the tube(weight of 0.023)had the highest and lowest priorities among the alternatives,respectively.The use of engineering noise control methods such as using silenced regulators was the best way to control the noises of CGSs.Additionally;it is noteworthy that AHP is a practical method for prioritizing alternatives to achieve the most accurate decision-making.The results of AHP can be of great help to health and safety experts and managers in choosing the sound engineering control measures more precisely.展开更多
Exposure to noise can lead to anatomical,nonauditory,and auditory impacts.The auditory influence of noise exposure is manifested in the form of Noise-induced hearing loss(NIHL).The current study aimed at present a sig...Exposure to noise can lead to anatomical,nonauditory,and auditory impacts.The auditory influence of noise exposure is manifested in the form of Noise-induced hearing loss(NIHL).The current study aimed at present a signal to noise ratio model of otoacoustic emission of rats’ears in the light of the combined effect of sound pressure level,sound frequency,exposure time,and potassium concentration of the used water.In total,36 adult male rates,whose age varied from 3 to 4 months and had a weight of 200±50 g,were randomly divided into 12 groups,with each group consisting of 3 rats.The rats in both groups(case and control groups)were exposed to SPLs of 85,95,and 105 dB,emitted from sources that generated white noise.A distortion product otoacoustic emission(DPOAE)machine(4000 I/O manufactured by Homoth of Germany)was utilized to gauge the signal to noise ratio(SNR)of otoacoustic emissions of rats’ears at various frequencies in an acoustic room.The inclusion criterion was SNR≥6 dB.The collected data were fed into the Statistical Package for Social Sciences(SPSS)version 18,followed by conducting descriptive and inferential data analysis procedures.The results of SNR analysis indicated that over 82%of all data had SNRs that were equal to or greater than 6 dB.These data were considered as acceptable response.Furthermore,SPL and sound frequency had significant associations with SNR(P<0.0001).Exposure time also significantly correlated with SNR(P=0.008).However,the potassium concentration of the used water had no significant correlation with SNR(P=0.97).High sound pressure levels result in lower DPOAE.Furthermore,higher frequency leads to higher SNR.On the contrary,longer exposure time reduces SNR.Finally,the potassium concentration of the used water has no effect on SNR.展开更多
In real life, when a noise problem occurs, it is important to identify the cause and measure the noise of the source, since it may affect human beings or other constructions due to vibration generated from noise, so i...In real life, when a noise problem occurs, it is important to identify the cause and measure the noise of the source, since it may affect human beings or other constructions due to vibration generated from noise, so it is necessary to determine the noise related to a specific source like a machine in the presence of other sources which is a very important approach in noise control engineering. In this article a full experiment was executed to measure the sound pressure levels of various sources (stationary and non-stationary), in both an anechoic chamber and a non-ideal noisy environment. The sound pressure level was extracted for different sources and compared for both ideal and non-ideal environment. The results showed that acoustical free field of the space is the best field to do measurements to avoid reflection, on the other hand the difference between the source and the background should be more than 3 dB to get better results.展开更多
Within previous EU projects, possible modifications to the engine components have been investigated, that would allow for an optimised aerodynamic or acoustic design of the EGV （exit guide vanes） of the TEC （turbin...Within previous EU projects, possible modifications to the engine components have been investigated, that would allow for an optimised aerodynamic or acoustic design of the EGV （exit guide vanes） of the TEC （turbine exit casing）. However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares the sound power level of a state-of-the-art TEC （reference TEC） with typical EGVs with an aerodynamically optimised TEC configuration for the engine operating point approach. It is shown that a significant weight reduction （only bladings considered） and reduction in engine length can be achieved but the sound power level for the fundamental tone （lst blade passing frequency） for this acoustically important operating point is increased. It is also shown that the losses of the aerodynamical optimised EGVs are higher for this off design point but significantly lower at the aero design point. Measurements were conducted in the STTF （subsonic test turbine facility） at the Institute for Thermal Turbo machinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes, the LPT （low pressure turbine） stage, and the EGVs have been designed by MTU Aero Engines.展开更多
The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environ...The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environmental sounds using the double-level energy detection (DED) was presented. The DED was used to detect the existence of the sound signals under noise conditions. In addition, MFCC features from the frames which were detected the presence of the sound signals by DED were extracted. Experimental results show that the proposed technology has better noise immunity than classic MFCC, and also outperforms time-domain energy detection (TED) and frequency-domain energy detection (FED) respectively.展开更多
矿用轴流式局部通风机在工作时产生强烈的噪声,严重危害工作人员的身心健康,降低风机噪声就成为亟待解决的问题。以一台FBS No 8.0型矿用两级轴流局部通风机为研究对象,采用大涡模拟(Large Eddy Simulation,LES)与基于Lighthill声类比的...矿用轴流式局部通风机在工作时产生强烈的噪声,严重危害工作人员的身心健康,降低风机噪声就成为亟待解决的问题。以一台FBS No 8.0型矿用两级轴流局部通风机为研究对象,采用大涡模拟(Large Eddy Simulation,LES)与基于Lighthill声类比的FW-H(Ffowcs Williams-Hawkings)模型相结合的方法,针对前级动叶5种周向非均匀分布方案,分别模拟得到风机的声功率级分布和不同区域气动噪声的时频特性,并与前级动叶周向均匀分布方案进行比较。结果表明:前级动叶的周向非均匀分布,打破其尾迹气流对下游导叶的周期性冲击,削弱前级动叶与中导叶之间的周期性干涉噪声,降低叶顶附近、叶片尾缘处和叶根处的声功率级;与前级动叶周向均匀分布的原风机叶顶区域压力脉动的时域特征相比前级动叶周向非均匀分布仅使其相位发生改变,幅值并无明显变化;考察的5种动叶周向非均匀分布方案,均能使风机在通过频率处发生调制现象,即将基频和谐频处所对应的离散噪声峰值均匀地分布于两侧,从而显著降低风机在通过频率处的离散噪声。展开更多
[背景]噪声性听力损失(NIHL)是工作场所常见的职业损害,且非稳态噪声暴露尤为普遍。目前已有基于线性回归的峰度调整等效声级(L'EX,8h)方法评估其对听力的损害,但因峰度作用复杂,仍需通过非线性回归引入新指标,以提高对非稳态噪声...[背景]噪声性听力损失(NIHL)是工作场所常见的职业损害,且非稳态噪声暴露尤为普遍。目前已有基于线性回归的峰度调整等效声级(L'EX,8h)方法评估其对听力的损害,但因峰度作用复杂,仍需通过非线性回归引入新指标,以提高对非稳态噪声致听力损失的预测精度。[目的]本研究旨在基于非线性回归探讨L'_(EX,8h)的调整项Ig(β_(N)/β_(G))及调整系数λ,并评估该方法在评估非稳态噪声所致职业性听力损失中的有效性。[方法]采用横断面研究设计,纳入1034名制造业工人,采集噪声暴露与听力损失指标。运用分位数回归分析量化测试频率为3、4和6 kHz的噪声性永久性听阈位移(NIPTS346)影响因素的贡献比例,通过多元线性回归及非线性最小二乘法计算L'_(EX,8h)。采用配对t检验分析峰度调整前后的预测效能,评估其对ISO 1999模型NIPTS346预测值的影响;利用Chow检验比较非稳态噪声(L'EX,8h)与稳态噪声(LEX,8h)的高频听力损失(HFINIHL)发病率logistic回归曲线相似性,进而评估L'_(EX,8h)的有效性。[结果]分位数回归结果显示峰度是评估非稳态噪声职业性听力损失风险的重要指标之一(贡献度为27.5%,P<0.05)。通过多元线性回归和非线性最小二乘法得到6个不同的调整系数λ与调整项Ig(β_(N)/β_(G))的组合,将不同的L'_(EX,8h)代入ISO 1999预测方程,结果均显著改善对NIPTS的低估L_(EX,8h)低估值为14.2 dB HL,L'_(EX,8h,n)低估值为11.5~5.6dB HL,P<0.001),L'EX,8h,6=LEX,8h+7.9Ig(βN/10)的改善效果最佳(低估改善8.7 dB HL)。logistic曲线中,所有L'_(EX,8h)对应的非稳态噪声剂量-效应关系曲线均较L_(EX,8h)更贴近稳态噪声组,其中L'_(EX,8h,6)所对应的回归曲线最为接近稳态噪声组(差值为4.1%)。[结论]L'_(EX,8h)能有效地评估非稳态噪声暴露导致的职业性听力损失风险。采用非线性回归法计算调整项、调整系数所构建的L'_(EX,8h)在评估非稳态噪声暴露导致的职业性听力损失时比线性回归法更加有效。展开更多
文摘Noise pollution is one of the common physical harmful factors in many work environments.The current study aimed to assess personal and environmental sound pressure level and project the sound-Isosonic map in one of the Razavi Khorasan Paste manufacture using Surfer V.14 and Noise at work V.5.0.This cross-sectional,descrip-tive study is analytical that was conducted in 2018 in the Paste factory that contains Canister,production and Brewing unit.Following ISO 9612:2009,Casella Cel-320 was used to measure personal sound pressure level,while CEL-450 sound level meter(manufactured by Casella-Cel,the UK)was employed to assess environmental sound pressure level.Statistical analyzes was done using SPSS V.18 and Linear Regression test.The sound-isosonic maps were projected using Surfer V.14 and Noise at work V.5.0.The results of assessing personal sound pressure level indicated that the highest received dose(172.21%)and personal equivalent sound level(87.36 dBA)were recorded for workers in the Canister unit.According to results of measuring of the environmental sound pressure level,out of 16 measurement stations in this unit,overall 87.5%were regarded as danger and caution areas.The lowest and highest sound pressure levels in this units were 61 dBA and 92 dBA that belong to Brewing and Canister units respectively.Results indicate Over 75%of the Canister and production units had a sound pressure level greater than 85 dBA and these two units were regarded as the most dangerous area in terms of noise pollution.It is there-fore necessary to implement noise control measures,apply hearing protection program and auditory tests among workers in these units.
文摘Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and implement noise control plans in occupational environments is necessary.Thus,the present study aimed to review environmental sound measurements,drawing of noise maps,and prioritizing the engineering noise control methods using the Analytic Hierarchy Process(AHP).This study was a descriptive-analytical study that aimed to assess occupational noises and present a control plan in the City Gas Stations(CGSs)of Kerman,Iran in 2021.The present study was done in two phases.In the first phase,six CGSs were investigated to measure and evaluate the noise.In addition,the noise map of a CGS was drawn using the Surfer software.Finally,the AHP was used in the second phase of the research to prioritize the control measures.In this phase,four criteria and ten alternatives were identified.According to first phase results,the sound pressure level(SPL)of the stations varied from 76 to 98 dBA.Besides,the majority of the studied stations had a sound level higher than 85 dBA(danger zone).The second phase of the study showed that out of the four evaluated criteria,the executability criterion had the highest impact and the cost criterion had the lowest impact on the selection of control measures with a weight of 0.587 and 0.052,respectively.Based on the results of prioritization of the alternatives,using a silenced regulator(weight of 0.223)and increasing the thickness of the tube(weight of 0.023)had the highest and lowest priorities among the alternatives,respectively.The use of engineering noise control methods such as using silenced regulators was the best way to control the noises of CGSs.Additionally;it is noteworthy that AHP is a practical method for prioritizing alternatives to achieve the most accurate decision-making.The results of AHP can be of great help to health and safety experts and managers in choosing the sound engineering control measures more precisely.
基金the output of a research project(registration number:24455)which was financially supported by Tehran University of Medical Sciences.
文摘Exposure to noise can lead to anatomical,nonauditory,and auditory impacts.The auditory influence of noise exposure is manifested in the form of Noise-induced hearing loss(NIHL).The current study aimed at present a signal to noise ratio model of otoacoustic emission of rats’ears in the light of the combined effect of sound pressure level,sound frequency,exposure time,and potassium concentration of the used water.In total,36 adult male rates,whose age varied from 3 to 4 months and had a weight of 200±50 g,were randomly divided into 12 groups,with each group consisting of 3 rats.The rats in both groups(case and control groups)were exposed to SPLs of 85,95,and 105 dB,emitted from sources that generated white noise.A distortion product otoacoustic emission(DPOAE)machine(4000 I/O manufactured by Homoth of Germany)was utilized to gauge the signal to noise ratio(SNR)of otoacoustic emissions of rats’ears at various frequencies in an acoustic room.The inclusion criterion was SNR≥6 dB.The collected data were fed into the Statistical Package for Social Sciences(SPSS)version 18,followed by conducting descriptive and inferential data analysis procedures.The results of SNR analysis indicated that over 82%of all data had SNRs that were equal to or greater than 6 dB.These data were considered as acceptable response.Furthermore,SPL and sound frequency had significant associations with SNR(P<0.0001).Exposure time also significantly correlated with SNR(P=0.008).However,the potassium concentration of the used water had no significant correlation with SNR(P=0.97).High sound pressure levels result in lower DPOAE.Furthermore,higher frequency leads to higher SNR.On the contrary,longer exposure time reduces SNR.Finally,the potassium concentration of the used water has no effect on SNR.
文摘In real life, when a noise problem occurs, it is important to identify the cause and measure the noise of the source, since it may affect human beings or other constructions due to vibration generated from noise, so it is necessary to determine the noise related to a specific source like a machine in the presence of other sources which is a very important approach in noise control engineering. In this article a full experiment was executed to measure the sound pressure levels of various sources (stationary and non-stationary), in both an anechoic chamber and a non-ideal noisy environment. The sound pressure level was extracted for different sources and compared for both ideal and non-ideal environment. The results showed that acoustical free field of the space is the best field to do measurements to avoid reflection, on the other hand the difference between the source and the background should be more than 3 dB to get better results.
文摘Within previous EU projects, possible modifications to the engine components have been investigated, that would allow for an optimised aerodynamic or acoustic design of the EGV （exit guide vanes） of the TEC （turbine exit casing）. However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares the sound power level of a state-of-the-art TEC （reference TEC） with typical EGVs with an aerodynamically optimised TEC configuration for the engine operating point approach. It is shown that a significant weight reduction （only bladings considered） and reduction in engine length can be achieved but the sound power level for the fundamental tone （lst blade passing frequency） for this acoustically important operating point is increased. It is also shown that the losses of the aerodynamical optimised EGVs are higher for this off design point but significantly lower at the aero design point. Measurements were conducted in the STTF （subsonic test turbine facility） at the Institute for Thermal Turbo machinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes, the LPT （low pressure turbine） stage, and the EGVs have been designed by MTU Aero Engines.
文摘The performance of classic Mel-frequency cepstral coefficients (MFCC) is unsatisfactory in noisy environment with different sound sources from nature. In this paper, a classification approach of the ecological environmental sounds using the double-level energy detection (DED) was presented. The DED was used to detect the existence of the sound signals under noise conditions. In addition, MFCC features from the frames which were detected the presence of the sound signals by DED were extracted. Experimental results show that the proposed technology has better noise immunity than classic MFCC, and also outperforms time-domain energy detection (TED) and frequency-domain energy detection (FED) respectively.
文摘[背景]噪声性听力损失(NIHL)是工作场所常见的职业损害,且非稳态噪声暴露尤为普遍。目前已有基于线性回归的峰度调整等效声级(L'EX,8h)方法评估其对听力的损害,但因峰度作用复杂,仍需通过非线性回归引入新指标,以提高对非稳态噪声致听力损失的预测精度。[目的]本研究旨在基于非线性回归探讨L'_(EX,8h)的调整项Ig(β_(N)/β_(G))及调整系数λ,并评估该方法在评估非稳态噪声所致职业性听力损失中的有效性。[方法]采用横断面研究设计,纳入1034名制造业工人,采集噪声暴露与听力损失指标。运用分位数回归分析量化测试频率为3、4和6 kHz的噪声性永久性听阈位移(NIPTS346)影响因素的贡献比例,通过多元线性回归及非线性最小二乘法计算L'_(EX,8h)。采用配对t检验分析峰度调整前后的预测效能,评估其对ISO 1999模型NIPTS346预测值的影响;利用Chow检验比较非稳态噪声(L'EX,8h)与稳态噪声(LEX,8h)的高频听力损失(HFINIHL)发病率logistic回归曲线相似性,进而评估L'_(EX,8h)的有效性。[结果]分位数回归结果显示峰度是评估非稳态噪声职业性听力损失风险的重要指标之一(贡献度为27.5%,P<0.05)。通过多元线性回归和非线性最小二乘法得到6个不同的调整系数λ与调整项Ig(β_(N)/β_(G))的组合,将不同的L'_(EX,8h)代入ISO 1999预测方程,结果均显著改善对NIPTS的低估L_(EX,8h)低估值为14.2 dB HL,L'_(EX,8h,n)低估值为11.5~5.6dB HL,P<0.001),L'EX,8h,6=LEX,8h+7.9Ig(βN/10)的改善效果最佳(低估改善8.7 dB HL)。logistic曲线中,所有L'_(EX,8h)对应的非稳态噪声剂量-效应关系曲线均较L_(EX,8h)更贴近稳态噪声组,其中L'_(EX,8h,6)所对应的回归曲线最为接近稳态噪声组(差值为4.1%)。[结论]L'_(EX,8h)能有效地评估非稳态噪声暴露导致的职业性听力损失风险。采用非线性回归法计算调整项、调整系数所构建的L'_(EX,8h)在评估非稳态噪声暴露导致的职业性听力损失时比线性回归法更加有效。
