A-weighted Equivalent Noise Level Research Articles

Prevalence and correlates of occupational noise-induced hearing loss among workers in the steel industry

BackgroundThe steel industry is one of the noisiest industries, which can predispose workers to hearing loss. In Egypt, the demand for steel is increasing due to the construction of new infrastructures as bridges, flyover roads, buildings, and towers; however, little is known about the prevalence of occupational noise-induced hearing loss (NIHL) among steel workers. Understanding the distribution of the affected workers is crucial for planning prevention strategies. This study aimed to estimate the prevalence of occupational NIHL among Egyptian steel workers and identify its correlates.MethodsThis study was conducted at two steel factories in Egypt in November 2021. It involved an initial retrospective review of the factory medical records of the latest periodic medical examination conducted on workers from July to September in the year 2021 representing workers’ health status in that year. Then, a case–control approach analysis was carried out. Eligible workers (n = 606) were enrolled and divided into two groups: noise-exposed workers (n = 396) and unexposed workers (n = 210). Univariate and multivariate regression analyses were performed.ResultsOccupational exposure to hazardous A-weighted equivalent noise level (> 85 dB) was associated with higher hearing thresholds at all frequencies (highest at 4 kHz followed by 6 kHz), particularly in younger workers below the age of 40 years. Nearly 71% of noise-exposed workers had hearing impairment, and 47% had NIHL compared with unexposed workers (45.7% and 11.9%, respectively). The probability of NIHL in noise-exposed workers was 6.55 times higher than that in unexposed workers (OR = 6.55, 95%CI = 4.13, 10.40; p < 0.001). In noise-exposed workers, age and tinnitus were independent predictors of hearing thresholds, while tinnitus was found to be an independent predictor of NIHL after adjusting for age and job duration (OR = 2.06, 95%CI = 1.01, 4.20; p = 0.045).ConclusionAlmost half of noise-exposed workers had NIHL. Tinnitus was found to be an independent predictor of NIHL. Decreasing noise exposure levels in steel plants is recommended to reduce hearing loss. Future research is required to study the effect of tinnitus on audiometry measurements among workers with NIHL.

WASN-Based Spectro-Temporal Analysis and Clustering of Road Traffic Noise in Urban and Suburban Areas

Environmental noise has become one of the principal health risks for urban dwellers and road traffic noise (RTN) is considered to be the main source of these adverse effects. To address this problem, strategic noise maps and corresponding action plans have been developed throughout Europe in recent years in response to the European Noise Directive 2002/49/EC (END), especially in populated cities. Recently, wireless acoustic sensor networks (WASNs) have started to serve as an alternative to static noise maps to monitor urban areas by gathering environmental noise data in real time. Several studies have analysed and categorized the different acoustic environments described in the END (e.g., traffic, industrial, leisure, etc.). However, most of them have only considered the dynamic evolution of the A-weighted equivalent noise levels LAeq over different periods of time. In order to focus on the analysis of RTN solely, this paper introduces a clustering methodology to analyse and group spectro-temporal profiles of RTN collected simultaneously across an area of interest. The experiments were conducted on two acoustic databases collected during a weekday and a weekend day through WASNs deployed in the pilot areas of the LIFE+ DYNAMAP project. The results obtained show that the clustering of RTN, based on its spectro-temporal patterns, yields different solutions on weekdays and at weekends in both environments, being larger than those found in the suburban environment and lower than the number of clusters in the urban scenario.

Aggregate Impact of Anomalous Noise Events on the WASN-Based Computation of Road Traffic Noise Levels in Urban and Suburban Environments.

Environmental noise can be defined as the accumulation of noise pollution caused by sounds generated by outdoor human activities, Road Traffic Noise (RTN) being the main source in urban and suburban areas. To address the negative effects of environmental noise on public health, the European Environmental Noise Directive requires EU member states to tailor noise maps and define the corresponding action plans every five years for major agglomerations and key infrastructures. Noise maps have been hitherto created from expert-based measurements, after cleaning the recorded acoustic data of undesired acoustic events, or Anomalous Noise Events (ANEs). In recent years, Wireless Acoustic Sensor Networks (WASNs) have become an alternative. However, most of the proposals focus on measuring global noise levels without taking into account the presence of ANEs. The LIFE DYNAMAP project has developed a WASN-based dynamic noise mapping system to analyze the acoustic impact of road infrastructures in real time based solely on RTN levels. After studying the bias caused by individual ANEs on the computation of the A-weighted equivalent noise levels through an expert-based dataset obtained before installing the sensor networks, this work evaluates the aggregate impact of the ANEs on the RTN measurements in a real-operation environment. To that effect, 304 h and 20 min of labeled acoustic data collected through the two WASNs deployed in both pilot areas have been analyzed, computing the individual and aggregate impacts of ANEs for each sensor location and impact range (low, medium and high) for a 5 min integration time. The study shows the regular occurrence of ANEs when monitoring RTN levels in both acoustic environments, which are especially common in the urban area. Moreover, the results reveal that the aggregate contribution of low- and medium-impact ANEs can become as critical as the presence of high-impact individual ANEs, thus highlighting the importance of their automatic removal to obtain reliable WASN-based RTN maps in real-operation environments.

Noise and Room Acoustic Conditions in a Tertiary Referral Hospital, Seoul National University Hospital.

Background and ObjectivesNoise levels and room acoustic parameters at a tertiary referral hospital, Seoul National University Hospital (SNUH) in Korea, are investigated.Materials and MethodsThrough a questionnaire, acoustically problematic rooms are identified. Noise levels in emergency rooms (ERs) and intensive care units (ICUs) are measured over about three days. Acoustically critical and problematic rooms in the otolaryngology department are measured including examination rooms, operating rooms, nurse stations, receptions, and patient rooms.ResultsThe A-weighted equivalent noise level, LAeq, ranges from 54 to 56 dBA, which is at least 10 dB lower than the noise levels of 65 to 73 dBA measured in American ERs. In an ICU, the noise level for the first night was 66 dBA, which came down to 56 dBA for the next day. The noise levels during three different ear surgeries vary from 57 to 62 dBA, depending on the use of surgical drills and suctions. The noise levels in a patient room is found to be 47 dBA, while the nurse stations and the receptions have high noise levels up to 64 dBA. The reverberation times in an operation room, examination room, and single patient room are found to be below 0.6 s.ConclusionsAt SNUH, the nurse stations and receptions were found to be quite noisy. The ERs were quieter than in the previous studies. The measured reverberation times seemed low enough but some other nurse stations and examination rooms were not satisfactory according to the questionnaire.

Analysis on hearing status and related influencing factors in workers exposed to noise in an automobile manufacture enterprise

Objective: To study the hearing status and analyze the related influencing factors in noise-exposed workers in an automobile manufacture enterprise, and put forward suggestions for prevention of noise-induced hearing loss. Methods: Noise exposure level testing, audiometry testing and questionnaires were performed for noise exposed workers in the automobile manufacture enterprise. To analyze the relationship between different factors and noise-induced hearing loss by cumulative noise exposure(CNE) calculated 8-hour continuous A-weighted equivalent noise level and seniority. Results: The detection rate of hearing loss in noise-exposed workers was 22.8%. The noise exposure intensity of stamping workshop is higher than other workshop, and the hearing loss detection rate of stamping workshop workers is higher than other workshop workers. The detection rate of hearing loss has significant difference in L(Aeq·8 h), seniority, CNE, age, high temperature and wearing earplugs (P<0.05). The results of logistic regression analysis showed that CNE, age and high-temperature were risk factors for noise-induced hearing loss (P<0.05 and OR>1) and there was an increasing tendency of hearing loss with increase in length of service and CNE, while using of earplugs was a protective factor (P<0.05 and OR<1). With the increase of CNE, the incidence of hearing loss is the rising trend. Conclusion: It is suggested to strengthen the noise control and individual protection and improve the high-temperature working environment, which plays an important role in reducing the occurrence of noise-induced hearing loss.

Temporal and spatial variations in road traffic noise for different frequency components in metropolitan Taichung, Taiwan

Road traffic noise exposure has been associated with auditory and non-auditory health effects, but few studies report noise characteristics. This study determines 24-h noise levels and analyzes their frequency components to investigate associations between seasons, meteorology, land-use types, and traffic. We set up 50 monitoring stations covering ten different land-use types and conducted measurements at three times of the year to obtain 24-h-average A-weighted equivalent noise levels (LAeq,24h) and frequency analyses from 2013 to 2014 in Taichung, Taiwan. Information on land-use types, road parameters, traffic flow rates, and meteorological variables was also collected for analysis with the annual averages of road traffic noise and its frequency components. The annual average LAeq,24h in Taichung was 66.4 ± 4.7 A-weighed decibels (dBA). Significant differences in LAeq,24h and frequency components were observed between land-use types (all p-values < 0.001), but not between seasons, with the highest two noise levels of 71.2 ± 1.0 dBA and 70.0 ± 2.6 dBA measured in stream-channel and commercial areas, with the highest component being 61.4 ± 5.3 dBA at 1000 Hz. Road width, traffic flow rates, and land-use types were significantly associated with annual average LAeq,24h (all p-values < 0.050). Noise levels at 125 Hz had the highest correlation with total traffic (Spearman's coefficient = 0.795) and the highest prediction in the multiple linear regression (R2 = 0.803; adjusted R2 = 0.765). These findings reveal the spatial variation in road traffic noise exposure in Taichung. The highest correlation and predictive capacity was observed between this variation and noise levels at 125 Hz. We recommend that governmental agencies should take actions to reduce noise levels from traffic vehicles.

Critical assessment of day time traffic noise level at curbside open-air microenvironment of Kolkata City, India.

BackgroundThe objective of the research work is to assess day time traffic noise level at curbside open-air microenvironment of Kolkata city, India under heterogeneous environmental conditions.ResultsPrevailing traffic noise level in terms of A-weighted equivalent noise level (Leq) at the microenvironment was in excess of 12.6 ± 2.1 dB(A) from the day time standard of 65 dB(A) for commercial area recommended by the Central Pollution Control Board (CPCB) of India. Noise Climate and Traffic Noise Index of the microenvironment were accounted for 13 ± 1.8 dB(A) and 88.8 ± 6.1 dB(A) respectively. A correlation analysis explored that prevailing traffic noise level of the microenvironment had weak negative (−0.21; p < 0.01) and very weak positive (0.19; p < 0.01) correlation with air temperature and relative humidity. A Varimax rotated principal component analysis explored that motorized traffic volume had moderate positive loading with background noise component (L90, L95, L99) and prevailing traffic noise level had very strong positive loading with peak noise component (L1, L5, L10). Background and peak noise component cumulatively explained 80.98 % of variance in the data set.ConclusionsTraffic noise level at curbside open-air microenvironment of Kolkata City was higher than the standard recommended by CPCB of India. It was highly annoying also. Air temperature and relative humidity had little influence and the peak noise component had the most significant influence on the prevailing traffic noise level at curbside open-air microenvironment. Therefore, traffic noise level at the microenvironment of the city can be reduced with careful honking and driving.

Characteristics Of Road Traffic Noise And Frequency Analysis In The Metropolitan Taichung, Taiwan

Introduction: This study determined 24-hour noise levels of road traffic noise and analyzed frequency components over one year to investigate associations between seasons, meteorology, land-use types and the traffic. Methods: We set up 50 monitoring stations (including 10 commercial areas, 10 residential areas, 5 industrial areas, 2 harbor areas, 8 culture-educational areas, 2 protective area, 3 scenic areas, 4 mountain areas, 3 agricultural areas and 3 green-land areas) to conduct 3-time measurements for 24-hour-average A-weighted equivalent noise levels (LAeq, 24h) and frequency analyses during 2013-2014 in Taichung. Information of land-use types, road parameters, traffic flow rates and meteorological variables were also collected to be associated with the annual average of road traffic noise and frequency components. Results: The annual average of LAeq, 24h in Taichung was 66.4±4.7 A-weighed decibel (dBA). No significant differences in LAeq, 24h between seasons were identified (p = 0.050). Significant differences in LAeq, 24h were observed between land-use types (p &lt; 0.001) to have the highest value of 70.2±3.2 dBA in commercial areas and the lowest one of 60.8±4.8 dBA in protective areas. We also found significant differences in annual average levels of LAeq, 24h between frequency components with the highest value of 61.4±5.3 dBA at 1k Hz and the lowest one of 31.5±4.9 dBA at 31.5 Hz. Multiple linear regressions showed that land-use types and traffic flow rates were significantly associated with the annual average of LAeq, 24h and exposure levels at different frequencies (all p values &lt; 0.050). Conclusions: These findings suggested that the annual average of LAeq, 24h in the Metropolitan Taichung was less than the hearing-loss threshold of 70 dBA recommended by World Health Organization except the commercial and harbor areas. Road traffic noise may have the highest level at 1k Hz and may be associated with land-use types and the traffic.

Traffic composition and variability of road traffic noise levels in the vicinity of Colombo, Sri Lanka

A study was conducted to determine the contribution of different types of vehicles to road traffic noise levels. Measurements were carried out on three different categories of roads at six separate locations, approximately 30 km away from the city of Colombo. At each location, continuous noise measurements were taken for a duration of 13 hours on weekdays and several key noise level descriptors (Leq, L10, L50, L90) were measured simultaneously. It was observed that A-weighted equivalent noise level (Leq) along main roads and secondary roads reached ~70 dB(A), which is the maximum permissible noise level prescribed for road traffic by Japan for residential areas. Similar to previous studies, a linear correlation was observed between Leq and other noise descriptors. Specially L10, which can be related to annoyance, can be estimated with an accuracy of ± 1 dB(A) by measuring Leq. The correlation between the rate of vehicle flow and the measured noise level showed a logarithmic relationship. It is shown that the key noise descriptors can be estimated with an accuracy of ± 2.5 dB(A) by measuring the flow rate of vehicles. The vehicle composition showed that heavy vehicles such as lorries, buses and containers contribute significantly to the average noise levels. J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 135-140

Relationship between road and railway noise annoyance and overall indoor sound exposure

Using data from a realistic experiment conducted using recorded traffic sounds, the relationship between indicators of magnitude, spectrum, and temporal evolution of the sonic environment and the reported annoyance are analyzed. The exposure is characterized by the binaurally recorded overall indoor sound. It is found that a series of parameters derived from multiple linear models related to the temporal and spectral structure of the sound pressure level produces better models than the overall indoor A-weighted equivalent noise level. The descriptors thus complement this indicator, at least when exposure is based on overall indoor sound. Principle components amongst the exposure indicators studied relate to the detectability of the sound indoors and to the typical temporal difference between road and rail traffic. Linear models based on these indicators also outperform models based on source related façade.

A simplified model for urban traffic noise prediction

A new simplified model for traffic noise prediction has been developed. The model predicts 1-hour A-weighted equivalent noise level L eq , in a simple way by assigning each variable into high, medium or low level. The significance of each variable that affects the traffic noise is also estimated.

Wideband micromachined capacitive microphones with radio frequency detection

Silicon microphones based on capacitive micromachined ultrasonic transducer membranes and radio frequency detection overcome many of the limitations in bandwidth, uniformity of response, and durability associated with micromachined condenser microphones. These membranes are vacuum-sealed to withstand submersion in water and have a flat mechanical response from dc up to ultrasonic frequencies. However, a sensitive radio frequency detection scheme is necessary to detect the small changes in membrane displacement that result from utilizing small membranes. In this paper we develop a mathematical model for calculating the expected output signal and noise level and verifies the model with measurements on a fabricated microphone. Measurements on a sensor with 1.3 mm2 area demonstrate less than 0.5 dB variation in the output response between 0.1 Hz to 100 kHz under electrostatic actuation and an A-weighted equivalent noise level of 63.6 dB(A) SPL in the audio band. Because the vacuum-sealed membrane structure has a low mechanical noise floor, there is the potential for improved sensitivity using higher carrier frequencies and more sophisticated detection circuitry.

Work conditions and health of locomotive engineers. I. Noise, vibration, thermal climate, diesel exhaust constituents, ergonomics.

Noise and vibration were measured in the cabs of 35 locomotives from 15 locomotive series. Noise exposure was estimated from measurements of A-weighted equivalent noise levels with personal noise dose meters. For the evaluation of the frequency .and fluctuation level, noise samples were recorded under different operating conditions. Forty-five percent of the measured equivalent noise levels exceeded 85 dB during a measuring period of 0.52 h. Vibration was measured from the seat of the locomotive cab, at the foot of the seat, and at the floor level. The most harmful vibr·ation was detected between 1 and 3 Hz of the 1/3 octave band, the 8-h risk limit of ISO standard 2631 often being exceeded in this range. The thermal climate in 20 locomotive cabs was evaluated under both summer and winter conditions with the measurement of temperature, velocity, relative humidity of the air, and globe temperature. The results were compared with the international comfort and health standards for climatic conditions. The analyses indicated nonuniform air temperature and draft in the cabs. These discomforts were caused by the cold air flow and the low surface temperature of the windows in winter. The thermal climate parameters often exceeded the comfort limit in summer. Diesel exhaust constituents were measured in the air of four roundhouses and of nine cabs during a trip. Four constituents with the highest dilution coefficients were chosen for measurement, namely, oxides of nitrogen, acrolein, formaldehyde, and total dlL9t. The Finnish threshold limit values of these substances were not exceeded. The highest values were obtained in the sheds, where the exposure times were very short. Ergonomic surveys utilizing spatial measurements, observation, photography, and interviews were made for the ten most common Finnish locomotive series in order to provide for recommendations both for the design of new locomotive types and for the modification of those in use. The features requiring the most urgent attention were connected with climbing in and out of the cab, as well as with the design of the seats, the controls, and the instrument board. The steps were usually in an upright angle, positioned at unequal intervals, and slippery; therefore the ascent and descent were dangerous. The seats were defective in design and poorly adjustable. The seat of the locomotive assistant was unfeasible in many cabs. The arrangement of the dials on the instrument board was often confusing. Many of the controls were far from the engineer and inadequately designed.