Equivalent Noise Level Research Articles

A Study on the Listening Environment in Schools for the Inclusive Education of Students with Hearing Impairments

Purpose: The purpose of this study was to investigate the listening environment for students with hearing impairments in inclusive education, providing fundamental data for establishing performance standards and improving classroom listening environments for these students.Methods: The teacher’s voice signal, classroom noise, and reverberation time were measured and analyzed in general classrooms, special education classrooms, and gymnasiums from 10 elementary schools where students with hearing impairments receive inclusive education.Results: The average equivalent noise level in the general classrooms was 56.8 dBA, and it was 53.4 dBA in the special education classrooms. The signal-to-noise ratio was +12.3 dB in the general classrooms, +15.7 dB in the special education classrooms, and +5.1 dB in the gymnasiums. The reverberation time was 0.4 seconds in the general classrooms, 0.5 seconds in the special education classrooms, and 0.8 seconds in the gymnasiums.Conclusion: Currently, it can be difficult for students with hearing impairments to effectively listen in inclusive educational environments. Therefore, improvements are needed to create better listening conditions.

Railway-induced vibration combined with railway noise - a systematic review with exposure-effect curves

The combined health impact of concurrent railway noise and railway vibration exposure is not yet well understood. This systematic review aimed to investigate the combined effects of vibration and concurrent noise. We converted the vibration metric to an equivalent noise level and calculated an overall noise level by energetically summing the equivalent and railway noise level. The combined health effect was determined by using published evidence-based exposure-effect formulas. Studies included in this systematic review predominately investigated annoyance and self-reported sleep disturbances; no studies on manifest diseases were identified. For the combined effects of vibration and noise on "total" annoyance, the results based on the pooled analysis of CargoVibes project are recommended as conservative approach. Our results based on epidemiological studies are corroborated by findings of laboratory studies. Converting railway vibration into equivalent noise levels in dB may offer a pragmatic approach to assess the combined health effects of railway noise and railway vibration exposure. Future studies should include cardiovascular and mental diseases in addition to vibration-induced annoyance and sleep disturbances. Furthermore, future studies should include in-depth investigations of the interaction between railway noise and railway vibration to allow for a more accurate assessment of the railway-induced burden of disease.

Analysis of noise characteristics of metal processing equipment

The management and prevention of industrial injuries among workers are crucial in the work environment. Industrial injuries occur in various forms and have diverse causes, and noise-induced hearing loss accounts for a significant proportion of workplace injuries. Therefore, this study aimed to measure the factory noise during engine-component (metal) processing for automobiles, where substantial noise-induced hearing loss is prevalent. The measurement results revealed that the 24-h equivalent continuous noise level (Leq) was approximately 83.8 dB(A), and the noise at two points was higher than the noise exposure standard of 89 dB(A). These points were identified as locations where 2,200- to 3,500-ton casting machines were positioned on both sides to melt iron to produce components. The noise generated from each machine is assumed to have combined at these points, resulting in elevated noise levels. The results were plotted on a noise rating (NR) curve. The NR values ranged from 81 to 83, surpassing the standard NR range of 60 to 70 that is commonly used in typical workplaces. The frequency band that determined the NR was 2 kHz. Therefore, measures such as the use of porous sound-absorbing materials should be considered to attenuate the frequency range based on the noise characteristics.

Assessment of environmental noise capacity for Indian Highways

India is one of the rising nations with a diverse traffic mix. Heterogeneity of traffic is a key factor in determining the noise environment around roadways. This study aims to assess the environmental noise capacity of Indian highways. To gather data for the study, Indian highways, namely NH-334, NH-7, and NH-344, were selected, specifically focusing on the sections, settlements near the highway. Four specific locations along these highways were chosen to measure the noise levels and collect comprehensive traffic data. The vehicles were classified into two categories: light vehicles and heavy vehicles. Traffic volume was assessed using videography, while traffic speed was determined using a radar gun. Sampling occurred at 15-minute intervals, encompassing both peak and off-peak hours on weekdays and weekends. A total of 460 data sets were collected to facilitate the prediction of equivalent noise levels (Leq). Environmental noise capacity (ENC) was calculated at all selected locations, revealing that the ENC value exceeded zero. This indicates that the noise levels in all areas surpassed the designated capacity. This study provides valuable insights for policymakers in developing strategies to mitigate the impacts of increasing highway noise.

A study on the difference in noise reduction between rear and side microphone on CPX measurement method through sound absorption frequency analysis

The road noise evaluation method in Korea is based on the 'noise vibration process test standard' by the Ministry of Environment. In this evaluation method, the noise felt at the sound-receiving point is measured as LAeq. Recently, in order to clarify the noise measurement standards for low-noise pavements, an international standard (ISO11819-2, CPX method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, CPX measurement method adopts side microphones as mandatory, and the rear microphone as optional. Due to the difference in location noise level is different, causing confusion in the road noise evaluation method. Researchers have published several studies in the past that the rear microphone is highly correlated with the equivalent noise level method based on the Korean standard. As a follow-up study to the above results, this study examines the characteristics and causes of the frequency spectrum of the rear and side microphones in the case of dense asphalt pavement and porous asphalt pavement and derives the results through frequency analysis of the sound absorption coefficient test to determine and to contribute improving reliability and institutional rationalization of the CPX measurement method.

Road Traffic Noise Levels Estimations by means of Fully Dynamic and Microscopic Approach Compared to CNOSSOS-EU Model

In the last decades, research has been dedicated to refining models for assessing traffic noise levels, supporting national authorities in addressing associated problems. Progress has shifted from basic statistical models to dynamic ones, typically composed of a Noise Emission Model (NEM) for estimating source sound power levels and a sound propagation model for assessing equivalent noise levels at specific receiver points. These models commonly integrate the average speed of traffic flow as an input variable, placing them in the macroscopic or mesoscopic realm. The CNOSSOS-EU model (reference in Europe) exemplifies this macroscopic approach. However, due to the modular structure of road traffic noise models, a NEM can be coupled with different sound propagation models, facilitating the transition from macroscopic to microscopic assessments. This paper demonstrates the coupling of a NEM with two distinct simplified sound propagation models: CNOSSOS-EU and the sum of Sound Exposure Levels (SEL) models. The latter approach showcases the potential of using individual on-road vehicle speeds as inputs, enabling microscopic noise assessments. Vehicle speed data is extracted from video records, while the goodness of the proposed approaches is tested by comparing the models' estimations with ground truth values recorded on a National Road in Portugal.

Noise and frequency propagation in natural stone processing plants

In this study, 510 noise measurements recorded in eight natural stone processing plants operating in Sivas City, Turkey were evaluated and the noise levels and dominant frequency bands of 11 different processing machines used in these plants were determined. The daily equivalent noise level of all natural stone processing plants was around or above the exposure limit value (87 dBA) specified in relevant regulations. Considering the machines and plant environment, the frequency ranges for the highest noise levels were mostly between 630 Hz - 5000 Hz, centering around 3150 Hz. Variations in the noise level of the processing machines in separate plants where similar processes were carried out was primarily related to the plant size and machine layout, the number of machines operating simultaneously and the type of natural stone processed. While the difference between the noise levels of gangsaws, bridge cutting, ST cutting, head/side cutting, trimming, cement filling, slab polishing, narrow polishing, chamfering and splitting machines were statistically significant, aging machines generated similar noise levels.

Analysis of Noise Level in Soekarno Hatta International Airport Area

One of the environmental impacts in the operation of an airport is noise, which originates from aircraft activities. Soekarno-Hatta International Airport is a public service airport located in Tangerang. This study aims to determine the noise levels around Soekarno-Hatta International Airport.The research results indicate that the noise levels of aircraft around Soekarno-Hatta International Airport in the northern part were collected using a sound level meter and then analyzed using the Weighted Equivalent Continuous Perceived Noise Level (WECPNL) method from aircraft landing activities. The results show that the noise intensity is categorized within the Weighted Equivalent Continuous Noise Level (WECPNL) range from ≥ 75 to ≥ 80 dBA.The researchers suggest that the airport authorities conduct regular noise measurements to monitor and control noise levels following the established noise standards and regulations to prevent direct impacts on the surrounding communities of Soekarno-Hatta International Airport

Multidimensional analysis of road traffic noise and probable public health hazards in Barisal city corporation, Bangladesh

Noise pollution is a major challenge in urban contexts all around the world. The study was designed to assess road traffic noise pollution with possible health effects on those living in the study region. The IDW spatial interpolation approach and an ArcGIS-based evaluation were used to map the recorded noise levels in the research region. The noise descriptors including Noise Climate (NC), Traffic Noise Index (TNI), Equivalent Noise Level (Leq), and Noise Pollution Level (NPL) were computed. The required information has been collected through a questionnaire survey and previously published documents. The study reveals that the current noise level is higher than the recommended national threshold at every location. According to the study, the Nathullabad region had the highest level of noise pollution (86.5 dBA), while the Kaunia Abasik area had the lowest level (67.8 dBA). Study findings also show that in the area context, the highest levels of noise pollution are found in commercial areas (82 dBA), followed by industrial areas (80.4 dBA),mixed areas (81.3 dBA), and residential areas (72.7 dBA). The lowest level is found in sensitive areas (72.5 dBA). Statistical analyses, including one-way ANOVA, Tukey HSD post-hoc and LSD post-hoc test results, showed that there was no statistically significant difference (p > 0.05) between the noise pollution levels (NPL) in the morning, noon, and evening shifts. The results showed that 32 % of respondents stated they felt disturbed while working, and 27% of respondents said it was somewhat sensitive for them. As the last step in minimizing noise pollution in the research area, 37 % of respondents reported enforcing the regulations, 31% suggested making hydraulic horns illegally, and 21 % suggested raising public awareness. This study may contribute to academic knowledge and assist decision-makers of government officials in formulating appropriate local strategies to deal with this grave environmental problem.

Commuter Experience: An Assessment of Metro-Train Comfort Amidst Operational Vibroacoustic Conditions

This study investigates the impact of different passenger rolling stock structures and train configurations on vibrations and noise generated during operation. Vibroacoustic measurements were performed during acceleration, constant speed, and braking phases to analyze the effects using statistical analysis according to the relevant standards, revealing a statistically significant relationship between the equivalent noise level and vibration dose. In the context of the expanding Warsaw metro network, which is adding new lines and modern rolling stock, trends in the development of metro rolling stock were analyzed using five different types of metro vehicles, from the oldest to the newest designs. Vehicle performance was ranked in the context of ride comfort using standards and combined vibration and noise measures. The research results allowed for a collective comparative assessment of the construction of individual types of passenger rolling stock in terms of vibroacoustic phenomena, thanks to which it is possible to assess the impact of modern solutions and the justification for investing in modern rolling stock. Newer trains generally record significantly lower vibration and noise levels. The difference between the oldest and the most modern vehicle types is 57% for the vibration acceleration level (0.08 ms−2 RMS) and 66% for the noise level (2.2 dB LAeq).

Detailed CNEL/Ldn roadway noise calculations vs. estimation methods

Roadway traffic noise calculations of the community noise equivalent level (CNEL) and the day-night average sound level (Ldn) metrics are sometimes required for various federal, state, and local government permitting requirements. To complete calculations of these metrics, detailed hourly traffic data is needed and obtaining this data can sometimes be a challenge. This paper explores various estimation strategies that are sometimes employed for situations where this data is not available and compares the estimates against calculations using detailed hourly traffic data to assess their validity. Project examples are provided of various permitting efforts such as those in support of California Environmental Quality Act (CEQA) documents, roadway projects at airports for Federal Aviation Administration (FAA) National Environmental Policy Act (NEPA) documents, and other local permitting requirements.

ASSESSMENT OF NOISE POLLUTION LEVELS IN AN ACADEMIC AREA OF AN ENGINEERING INSTITUTE IN INDIA

Present study focuses on typical noise assessment at 29 key locations in an academic area of a college during academic and non-academic hours, and comparison with Indian standards for sensitive zone. The equivalent continuous noise levels (L_Aeq) were observed to be exceeding the permissible limits of 50 dB L_Aeq during day time and 40 dB during night time on weekday as well as weekend of classrooms, corridors, central workshop and open spaces in academic area. The average L_Aeq values for the entire academic area on weekday during day time (65.88 dB), weekday night time (47.70 dB), weekend day time (57.73 dB) and weekend night time (45.77 dB) were also observed to be 31.77 %, 19.24 %, 15.45 % and 14.43 % respectively higher than the prescribed standards for educational/ academic institutes. Further, noise maps were created by ArcGIS using Inverse Distance Weighting (IDW) technique showing noise hotspots at a glance.

Impact of low-frequency noise on a residential zone due to commercial HVAC systems

Low frequency noise (LFN) is a serious growing global challenge for the urban environment where noise itself is an undervalued pollutant. The commercial establishments are equipped with multiple HVAC (Heating Ventilation and Air Conditioning) units responsible for the generation of LFN. To assess the impact of LFN, the noise was monitored using A and C-weighting sound level meters at HVAC outlets as well as in and around the residential premises. The noise due to HVAC units is found to be highly intensive in the lower frequency zones (<250Hz), affecting psychological and physiological health of living beings in the residential zones. A substantial 39.4 dB sound pressure level discrepancy between A and C-weighting inside the residential premises underscores the pronounced predominance of low-frequency noise. Noise monitoring using A-weighting failed to highlight the significant impact of lower frequency octave bands. The C-weighting noise monitoring revealed a substantial contribution of lower frequency octave bands (8Hz–250Hz) with 48.2 dB(C), in the overall equivalent noise level of 48.6(C), primarily attributed to HVAC units. The study suggests monitoring and assessment of the LFN, its mitigation and control strategies and its impact on the noise environment, especially on a residential zone.

Diurnal rail noise measurement, analysis, and evaluation of associated health impacts on residents living in the proximity of rail track area.

In India, railway is the major transportation mode for carrying goods and people. The tracks for the movement of the rail were initially constructed in the city for the pre-eminence and expediency of the vantage of the people. Rapid modernization and increasing population in the city crammed the area around the railway tracks. Moving rail on the tracks passing through the city is not compatible, which is creating problems for the nearby residents. In the urban and suburban regions, the railway noise has become a major problem. This study was conducted to examine the perception of the physiological and psychological effects of railway noise in the nearby areas of railway stations in Delhi, India. For this purpose, 10 sites near the railway station were selected for the study. To assess the impact of railway noise pollution on the health of humans, a questionnaire survey was conducted. The data of 344 individuals were collected through the questionnaire survey and analyzed to get the perception towards railway noise. Noise level was monitored by a Sound Level Meter (SLM) and the equivalent noise level (Leq) in dB(A) was used to compute the noise pollution in three shifts, i.e., morning, noon, and evening time. Results showed that 57.65% of female and 86.11% of male respondents in the survey reported the disturbance due to railway noise. The level of noise pollution was found higher in the evening time as compared to the noon and morningperiod, which exceeds the limit set by the Central Pollution Control Board (CPCB) at all the monitored locations. Findings of the study show that the primary cause of the health problems is railroad noise, which is negatively impacting the health of the residents, who are living in the proximity of the rail track region. The perception survey reported that headache, sleep disturbance, irritation, and stress are common health issues among the locals residing around the railway track proximity in Delhi.

Prediction of Noise Level in Ota Metropolis Using Artificial Neural Network

Capturing noise data is laborious, time-consuming, expensive and dangerous due to the exposure of the investigator to the menace. Also, appropriate software, computational skill and computational time are also required before the captured data could be of any use. In this work, an artificial neural network (ANN) was deployed to learn and train noise data in Ota Metropolis. Data were captured from forty-one (41) locations for the morning, afternoon and evening in Ota Metropolis. ANN with Levenberg Marquardt algorithm and architectural configuration of 2-21-9 (input-hidden neuron-output) was used to predict noise descriptors for Ota Metropolis with 73% accuracy. The two input variables were the latitude and longitude of the location measured in degrees while the nine output variables are the noise descriptors such traffic noise index (TNI), noise pollution level (LNP), and average equivalent noise levels (LAeq) computed for each selected location for morning, afternoon and evening periods. The results could be used in mobile applications, Google Earth and other platforms to guide residence dwellers, travellers, industrialists and technocrats in selecting travelling routes, choice of apartment location and use of appropriate personal protective equipment (PPE) in unavoidable noisy locations.

Assessment and mapping of noise pollution in recreation spaces using geostatistic method after COVID-19 lockdown in Turkey

Increased use of recreational areas after the lifting of COVID-19 pandemic restrictions has led to increased noise levels. This study aims to determine the level of noise pollution experienced in recreational areas with the increasing domestic and international tourism activities after the lifting of pandemic lockdowns, to produce spatial distribution maps of noise pollution, and to develop strategic planning suggestions for reducing noise pollution in line with the results obtained. Antalya-Konyaaltı Beach Recreation Area, the most important international tourism destination of Turkey, is determined as the study area. To determine the existing noise pollution, 31 measurement points were marked at 100 m intervals within the study area. Noise measurements were taken during the daytime (07:00–19:00), evening (19:00–23:00), and nighttime (23:00–07:00) on weekdays (Monday, Wednesday, Friday) and weekends (Sunday) over 2 months in the summer when the lockdown was lifted. In addition, the sound level at each measurement point was recorded for 15 min, while the number of vehicles passing through the area during the same period was determined. The database created as a result of measurements and observations was analyzed using statistical and geostatistical methods. After the analysis of the data, it was found that the co-kriging-stable model showed superior performance in noise mapping. Additionally, it was revealed that there is a high correlation between traffic density and noise intensity, with the highest equivalent noise level (Leq) on weekdays and weekend evenings due to traffic and user density. In conclusion, regions exposed to intense noise pollution were identified and strategic planning recommendations were developed to prevent/reduce noise sources in these identified regions.

Acoustic Impact of Rail Transport on Residential Areas of the City of Voronezh

Introduction: Adverse human health effects of railway noise are examined in many foreign and domestic studies. The purpose of our work was to assess the noise impact of rail transport and its contribution to creating an acoustic discomfort zone in residential areas of the city of Voronezh. Materials and methods: We took 36 noise measurements at nine monitoring points in the residential area of single-family housing construction at the distances of 25, 50, and 75 meters from the main local source of noise, i.e. railway traffic, including long-distance and suburban passenger trains. The “Assistant” sound level meter (accuracy class 1) was used for measurements taken in November 2023 – January 2024 on weekends (Sat–Sun) in the daytime and at night. Contribution of railway transport to the overall noise level was then estimated. Results: Field measurements showed that in the daytime, the equivalent noise level along the railway track exceeded hygienic standards by 1.4 to 1.7 dBA in the absence of railway traffic due to the proximity to a highway (70 m) and by 14 to 18.6 dBA in its presence; at night – by 2.2 to 3.2 dBA and by 25 to 29.9 dBA, respectively. This means that during 24 hours, 30 % of the territory of the study object is exposed to higher noise levels in the absence of railway traffic. During the passage of long-distance passenger trains and suburban electric trains, the discomfort zone increases to 60 % in the daytime and to 100 % at night. Conclusions: In our case, rail transport noise pollution can be reduced by installing additional translucent noise shields, landscaping the adjacent territory to separate residential buildings from railway tracks, and planting trees and shrubs. In general, when designing railway lines and their infrastructure facilities, it is important to envisage sanitary gaps with modern means of protection against noise.

Ultra-low noise front-end design for smart optical sensors with high sensitivity and wide dynamic range.

Ultra-low noise is a critical component in the design of high-precision sensor front-ends. We introduced differential phase-sensitive detection (d-PSD) to mitigate both multiplicative and additive noise in optical sensors, aiming for an enhanced performance and cost-effectiveness. The d-PSD combines a capacitive transimpedance amplifier (C-TIA), a delta-sigma analog-to-digital converter (ΔΣ-ADC), and a software-based lock-in amplifier (s-LIA). The first two components utilize the DDC112 (a dual current input 20-bit ADC) for a minimal analog channel length, thus reducing noise efficiently, while the latter employs a cost-effective 32-bit microcontroller unit (MCU), the HC32F460. This approach was successfully implemented as the front-end for a smart optical sensor. Testing indicated that the sensor achieved an equivalent current noise level of 0.6 nA/√Hz, primarily attributed to the light source driver rather than the sensor's front-end circuit. The sensor exhibited an exceptional performance, with a 3σ measurement precision of 5.4 × 10-4 over a 1-second integration time and a dynamic range of 100 dB, leveraging the proposed method and design. Furthermore, the front-end of the sensor boasts a compact size, low power consumption, and affordability, making it an ideal, versatile solution for ultra-high precision, smart optical sensors.

Analisis Keterkaitan Antara Aktivitas Kendaraan Bermotor dengan Tingkat Kebisingan: Studi Kasus di Jalan Gatot Subroto, Kota Palu

The elevation of mobility in Palu has evolved into a new noise issue. Noise from motorized vehicles has quite an impact on the tranquility of areas that directly intersect with the highway. Gatot Subroto Axis Road is an instance of a congested road as public facilities such as educational institutions take the crowd of the area. The study aims to analyze the relationship of vehicle activities toward noise level at Gatot Subroto. The research method uses field measurement by a sound level meter (SLM), tripod, and counter. Noise sampling standards refer to SNI 8427:2017 regarding measuring environmental noise levels. Data was collected for one day on weekdays and weekends with three take times at three sampling points. Noise level analysis is carried out using frequency distribution. The next data analysis is to look for the equivalent noise level or LAeq. The noise level points varied between 71,6 dBA-84,02 dBA. The traffic volume reached a peak at 853. The p-value was 0,72 which was above 0,05. The regression test was Y=0,0048x+72,904, and R2 showed 0,15 points, which means that 15% of the noise level was affected by traffic volume. In conclusion, the average noise level at Gatot Subroto Axis Road exceeded the quality standards set according to the Decree of the Minister of State for the Environment No. 48 of 1996, which is 55 dB(A). Despite no significant difference in noise levels on weekdays and weekends based on the t-test, the noise level is affected by traffic volume. Noise from motorized vehicles has quite a big impact on the tranquility of areas that directly intersect with the highway. he limitation of this research is the limited amount of data due to the small number of research points and the insufficient number of days, so further research is needed.

Evaluation of Equivalent Noise Levels across Some Commercial Areas of Warri and Benin Metropolis in Nigeria

Globalisation has given rise to an increase in the amount of noise generated around us, such that man has adjusted to this increment without considering the possible risks associated with it. This study aims to measure the equivalent noise level in eighteen (18) locations in some commercial areas of Warri and Benin Metropolis in Nigeria using a noise level metre (Model: CEL-231). The assessment was done twice daily, during the day and at night. The results obtained revealed that the daytime equivalent noise level of both cities ranged from 48–68, 78–102 dBA for minimum and maximum noise levels, while the nighttime equivalent noise level ranged from 39–59, 59–83 dBA for minimum and maximum levels, respectively. It was observed that the daytime noise level values in some locations for both cities were higher than the nighttime values and also higher than the recommended standard noise quality description for daytime and nighttime duration as recommended by the World Health Organization (WHO) and some existing literature in Nigeria and across the globe. The reason for this noise level elevation is due to the activities of automobiles and tricycles plying the road incessantly, and again, these are major industrial cities with a lot of activities during the daytime. However, it can be recommended that those whose daily activities confine them to areas with unhealthy noise levels ensure at least 10 hours of recovery time in areas where the sound level is less than 65 dBA and also encourage the planting of trees in this vicinity