Minimum Noise Level Research Articles

A study on the perception of refrigerator noise in everyday life

Advancements in technology and noise control measures significantly reduced the noise emissions of refrigerators. Despite the achievement of low sound power levels in modern refrigerators, substantial efforts are still dedicated to further minimizing their noise. This initiated an examination into the need for ongoing activities to reduce noise, given the already minimal noise levels. This study aimed to evaluate the impact of refrigerator noise in everyday life, examining the circumstances and extent of individuals' exposure to noise while exploring their general perception. In an online survey, attention to refrigerator noise was explored to understand how often respondents can hear refrigerator noise in their daily lives. In addition, questions about the operating conditions of the refrigerator, in particular at the times when participants could hear refrigerator noise, were also assessed in the survey. Finally, the results of measurements that generalize the extent to which refrigerator noise can exceed background noise in normal rooms were also evaluated in this study.

Impact of Ship Noise on Seafarers’ Sleep Disturbances and Daily Activities: An Analysis of Fatigue Increase and Maritime Accident Risk through a Survey

This study delves into the impact of ship noise on seafarer well-being, emphasizing fatigue—a significant contributor to maritime accidents due to human error. The investigation, centered around the hypothesis that IMO ship construction standards may not adequately minimize noise levels in seafarer cabins, seeks to establish whether these levels are sufficient to ensure seafarer security and prevent sleep disturbances. According to current IMO regulations, noise levels are set at 55 dB for vessels under 10,000 gross tonnage and 60 dB for those over 10,000, yet WHO guidelines recommend a maximum of 40 dB in bedrooms to avoid sleep disruption. A comprehensive survey involving 221 cadets demonstrates that 79.6% of participants experience sleep disturbances, work disruptions, and stress due to noise, indicating that the present noise standards are insufficient. This paper argues that reducing noise levels in individual cabins to below 40 dB is critical for enhancing seafarer health and safety and could significantly reduce human error-related maritime accidents. The findings advocate for more stringent noise control measures and regulatory reforms to bridge the knowledge gaps and improve labor protection in the maritime industry.

A MEMS Electrochemical Angular Accelerometer with Silicon-Based Four-Electrode Structure.

This paper presents a MEMS electrochemical angular accelerometer with a silicon-based four-electrode structure, which was made of thousands of interconnected microchannels for electrolyte flow, anodes uniformly coated on structure surfaces and cathodes located on the sidewalls of flow holes. From the perspective of device fabrication, in this study, the previously reported multi-piece assembly was simplified into single-piece integrative manufacturing, effectively addressing the problems of complex assembly and manual alignment. From the perspective of the sensitive structure, in this study, the silicon-based four-electrode structure featuring with complete insulation layers between anodes and cathodes can enable fast electrochemical reactions with improved sensitivities. Numerical simulations were conducted to optimize the geometrical parameters of the silicon-based four-electrode structure, where increases in fluid resistance and cathode area were found to expand working bandwidths and improve device sensitivity, respectively. Then, the silicon-based four-electrode structure was fabricated by conventional MEMS processes, mainly composed of wafer-level bonding and wafer-level etching. As to device characterization, the MEMS electrochemical angular accelerometer with the silicon-based four-electrode structure exhibited a maximum sensitivity of 1458 V/(rad/s2) at 0.01 Hz and a minimum noise level of -164 dB at 1 Hz. Compared with previously reported electrochemical angular accelerometers, the angular accelerometer developed in this study offered higher sensitivities and lower noise levels, indicating strong potential for applications in the field of rotational seismology.

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

Automatic Continuous Thrust Control for Supersonic Transport Takeoff Noise Reduction

Advanced takeoff trajectories are proposed for supersonic transport noise reduction by capitalizing on excess engine thrust and improved aerodynamic efficiency at higher takeoff speeds. These novel trajectories use i) automatic continuous control of thrust, ii) increased takeoff speed, and iii) reduced cut-back altitude, compared to conventional pilot-initiated discrete thrust cut-back procedures currently used for subsonic transport. In this paper, we develop an optimal control framework to assess the attributes of effective takeoff trajectories for supersonic transport that yield minimum noise levels. We quantify the noise reduction potential of advanced takeoff trajectories for the eight-passenger, 55-metric-ton, Mach-1.4 NASA Supersonic Technology Concept Airplane. For the aircraft examined, these advanced takeoff trajectories enable a cumulative certification noise reduction of 10.6 EPNdB, which is insufficient to meet current subsonic transport noise limits.

Analysis of noise pollution level in and around SIDCUL area in District Haridwar (Uttarakhand) India

The primary objective of this study is to evaluate the issue of noise pollution in the vicinity of the industrial zone of Haridwar city and its correlation with the health of the people in and around the SIDCUL (State Industrial Development Corporation of Uttarakhand Limited). The study revealed that noise pollution levels were above the CPCB Standard for the sound level for industrial zones and residential zones. During the period from January to December 2018, noise levels were observed and monitored in both the industrial zone (Site-I SIDCUL) and the residential zone (Site-II Siwalik Nagar). The average noise levels varied throughout the year. At Site-I (Industrial Zone), during the daytime in July, the maximum average noise level recorded was 89.5 dB, while in April; the minimum average noise level was 81.1 dB. During nighttime, in January, the maximum average noise level reached 84.1 dB, and in May, the minimum average noise level was 76.6 dB. In Site-II Siwalik Nagar (Residential Zone), the daytime noise levels were a maximum average noise level of 61.1 dB in May and a minimum average noise level of 58.8 dB in September. During nighttime, the noise level reached a maximum average of 47.2 dB in October and a minimum average of 44.5 dB in May. Overall, the study revealed that noise levels were generally higher in both zones, except for the average nighttime noise level at Site II (residential zone), which was below the prescribed standard limit for noise.

Effect of background noise on speech privacy

There is a need for speech privacy in many building environments, which is often affected by various factors such as human perception, acoustic separation of partitions, and background noise levels. Previous studies have classified speech privacy rating between spaces based on partition separation and internal noise in receiving spaces. However, the typical design process often overlooks a holistic approach to speech privacy. Green buildings, focused on sustainability, have recently gained global attention. They aim to reduce environmental impact while ensuring comfort and health for occupants through energy-efficient HVAC systems, sustainable insulation, and low emissivity glazing. Despite their benefits, energy-efficient HVAC systems can emit minimal noise levels. The low internal noise levels in green buildings can often adversely affect the speech privacy rating between spaces. The Green Building Council of Australia have recently addressed the requirement of speech privacy by introducing the need for minimum internal noise levels in the Green Star Buildings, in addition to the acoustic separation requirements between spaces. This paper aims to investigate the need for minimum internal noise levels to address the requirement of speech privacy holistically rather than addressing acoustic separation and internal noise levels as individual components of acoustic design.

Acoustic ceiling systems inside buildings: What we were taught and should now know instead

This presentation is an executive summary of how modular, suspended, acoustic, ceiling systems perform inside buildings as presented at meetings of the Acoustical Society of America and noise control engineering conferences between 2015 and 2022. It bridges the gap between laboratory testing of ceiling panel metrics and how complete ceiling systems perform inside buildings when combined with other building elements such as lights, air diffusers, floor slabs, plenum barriers and mechanical devices in the plenum. Ceiling system performance will be discussed from the perspectives of complying with minimum sound absorption, minimum sound isolation and maximum background noise level requirements in building design standards and guidelines. Corroboration with foundational testing conducted by the National Research Council of Canada and ASHREA will be integrated. Standards with prediction methods that should be used instead of ceiling panel metrics will be reviewed. Citations to studies will be provided for more detailed information.

A Two-Step Approach for the Analysis of Bulk Current Injection Setups Involving Multiwire Bundles

In this work, a two-step procedure to predict maximum (worst-case scenario) and minimum (best-case scenario) noise levels induced by bulk current injection (BCI) at the terminal sections of a wiring harness is presented. To this end, common mode (CM) and differential mode (DM) quantities are introduced by a suitable modal transformation, and equivalent modal circuits are derived, where CM (dominant mode) into DM (secondary mode) conversion is modelled by induced sources included into the DM circuit. The procedure initially foresees the solution of the CM circuit to provide input data for subsequent solution of the DM circuit. Such a two-step approach is then used to develop a probabilistic–possibilistic framework for computationally-efficient estimation of lower and upper boundaries to the variability of the noise voltages induced at the bundle terminations. To this end, random uncertainty affecting certain setup parameters is addressed through probability theory, whereas epistemic uncertainty is represented via possibility theory. Accuracy and computational efficiency of the proposed two-step method are assessed by examples involving seven and nineteen wire harnesses.

Recent Advancement in Savonius Wind Turbine- A Review

In the steps to save our earth from global warming every nation focused on their own way to promote green energy among which the Savonius vertical axis wind turbine is one of the excellent viable solutions for scavenging wind energy in a downtown background, due to distinctive characteristics such as compactness, self-starting ability at light wind, minimum noise level, with relatively reasonable price and simple assembly. However, the traditional Savonius Wind Turbines with semicircular blades has a proportionately low power coefficient together with a high negative torque produced by the returning blade is a crucial disadvantage of this rotor. This work focuses on reviewing and giving an overview on the form of the wings of Savonius Vertical Axis Wind Turbine. This paper also aims to give a run through of the several augmentation approaches used in Savonius rotor over the last four decades. In this paper, a brief on all possible segments and parts of the machine is given after a brief analysis and research on each topic.

Vehicular pollution prediction using HWTO‐ANFIS model in urban areas of Hyderabad City

AbstractAir pollution has become a life‐threatening factor around the world in recent decades as a result of vehicles, industrialization, human activities, and urbanization. The existing vehicular air pollution prediction studies met several shortcomings in terms of poor prediction accuracy, higher error rates, huge execution time and etc. To tackle these challenges, this study proposed a Hybrid Whale Tabu Optimization‐based Adaptive Neuro‐Fuzzy Inference System (HWTO‐ANFIS) predict the effects of vehicular pollution in urban areas. The major objective of this paper is to minimize the forecasting error and get optimal results during pollution prediction. The average, minimum and maximum noise levels of vehicles are effectively predicted using the proposed HWTO‐ANFIS model. The proposed model efficiency is evaluated using various performance measures such as Normalized Mean Square Error, Mean absolute percent error, Mean Absolute Error, Average Error and Root Mean Square Error respectively. The MATLAB software performs the implementation work. Hyderabad city based vehicular pollution data is taken and analyzed to predict environmental pollution based on vehicles. For the analysis of the dataset, the number of pollutants is considered and the Air Quality Index (AQI) is also determined. The proposed hybrid method is tested and evaluated with the existing methods like Artificial Neural Networks (ANN) and Fuzzy Logic Controllers (FLC). In this study, the proposed HWTO‐ANFIS model is utilized to predict vehicular pollution in the last years such as 2018, 2019, 2020 and 2021, respectively. The proposed method's accuracy is 7%–12% greater than that of other conventional techniques. However, the proposed method offers superior detection performances than other state‐of‐art methods.

A report on a modified protocol for flow cytometry-based assessment of blood group erythrocyte antigens potentially suitable for analysis of weak ABO subgroups.

Flow cytometry (FC) has proven its utility in scrutinizing AB antigen expression in red blood cells (RBCs), cooperating with serological tests for accurate blood group typing. However, technical difficulties may impair the characterization of weak ABO subtypes when background noises appear at non-negligible levels. We sought to establish an FC method that could prevent antibody-induced hemagglutination and an increase in cellular autofluorescence, two major issues inherent to RBC-FC analysis of AB expression. We optimized fixatives, multicolor-staining protocols, and sequential gating strategies. Blood samples from weak ABO subtype cases, Bm and Ael , were analyzed with the established protocol. The optimized mixture of glutaraldehyde and formaldehyde successfully generated fixed RBCs resistant to agglutination while maintaining low autofluorescence. These features allowed co-staining of leukocyte- and erythrocyte-markers, which enabled sequential gating strategies facilitating the precise AB antigen analysis in purely single RBCs with minimum background noises. By the established FC analysis, we could detect in the Bm sample a small RBC population exhibiting weak B antigen expression. The assay also proved it feasible to identify a small population (0.04%) of RBCs weakly expressing the A antigen in the Ael sample confirmed as harboring a rare c.816dupG ABO variant allele. The RBC-FC analysis described here allows the detection of AB antigens weakly expressed in RBCs while achieving minimum background noise levels in negative control samples. Overall, the modified protocol provides a quick and reliable assay valuable in transfusion medicine and is potentially applicable to the characterization of rare weak ABO variants.

Prediction of traffic noise induced annoyance of vendors through noise indices using structural equation modeling: Artificial neural network model

AbstractUrbanization and population growth, as well as the movement of diverse vehicles on urban roadways, all contribute to excessive noise in the urban acoustic environment. Annoyance, cardiovascular disease, dementia, hypertension, stress, sleeping problem, irritation, hair‐fall, headache, are the most common reported problems due to traffic noise exposure. The “Structural Equation Modeling–Artificial Neural Network Model” was used in the current study to predict traffic noise induced annoyance among 100 vendors whose shops are located from Khandagiri to Baramunda along the National Highway 16 of the smart city Bhubaneswar Odisha. Due to the movement of large number of heavy vehicles as well as medium and light weight vehicles, these roadways remain noisy throughout the day. Moreover, the annoyance questionnaire was developed in compliance with ISO/TS 15666 criteria for assessing annoyance level. The combination of SEM and ANN is rarely seen in acoustics, especially in noise studies. However, in this study, both SEM and ANN are used to predict annoyance using various noise indices. Moreover, the SEM model revealed a significant association between “Equivalent Noise Level” (Leq) and annoyance (p‐value = 0.031), “Minimum Noise Level” (LMin) and annoyance (p‐value = 0.049), “Background Noise Level” (L90) and annoyance (p‐value = 0.047), “Noise Pollution Level” (NPL) and annoyance (p‐value = 0.038). These associations indicate that Leq, LMin, L90 and NPL have a significant effect on annoyance. Furthermore, the PLS algorithm output from the measurement model verified a 47 percent variance in annoyance level. The ANN model confirmed that NPL is the most significant predictor of noise annoyance, followed by LMin, Leq, and L90. Moreover, the ANN model can predict annoyance with an accuracy of 68.5 percent.

The Selection of Propeller and Primary Engine Matching of A 30 GT Fishing Vessel (Case Study KM Inka Mina 759)

Reducing fuel consumption and carbon emissions in the development of ship propulsion systems following the required Energy Efficiency Design Index (EEDI) has become a concern for the fishing industry as determined by the International Maritime Organization (IMO). This study analyzes the suitability of using a 30 GT fishing vessel propeller and propulsion engine for optimum efficiency. The analysis focuses on developing a propulsion system selection model, studying the characteristics of the ship's resistance, loading propellers, and selecting the appropriate engine. The propeller-engine matching procedure predicts the propeller and engine suitability. Furthermore, the Analytic Hierarchy Process (AHP) method determines the suitability level for the propeller and diesel engine. The results showed the highest level of suitability for the Yanmar 6CH-HHTEC engine versus the A.30X34 type propeller with 31.7%. Then the Deutz BF06M1013MC engine versus the B.30X28 propeller type, the Yuchai YC6A170C engine versus the B30X28 propeller type, and the Volvo D7ATA engine versus the B30X28 propeller type with percentages of 26.6%, 26.4%, and 15.3%, respectively. The high level of SP2 selection is due to the propulsion system having minimal noise levels, dimensions, and engine weight but having maximum power.

Hearing Status and Noise Exposure Levels of Workers at a Laundry Plant in Sri Lanka

Purpose: The aim of this study was to determine the hearing status and noise exposure levels of workers at a laundry plant in Sri Lanka.Methods: A descriptive cross-sectional study was done to determine the noise levels workers were exposed to during their shifts, to evaluate hearing-related complaints, to evaluate audiometric measures of the workers, and lastly to determine the association between the job category and hearing status. The study included 107 workers between the age of 20~50 years. Noise levels of the laundry plant were measured and data was gathered via an interviewer-administered questionnaire and screening and diagnostic hearing tests were performed.Results: The minimum and maximum noise levels were 63.1 dBA and 100.3 dBA. Among workers, 40.18% indicated abnormal audiograms. Among those who had abnormal audiograms, 31.77% were diagnosed with noise induced hearing loss (NIHL) in the right ear while 28.03% had NIHL in the left ear.Conclusion: There was no significant association between the degree of hearing loss and exposure duration of the workers as well as hearing status with reference to the job category. However, the workers in the dryer and hydro sections were at high risk for NIHL, as the mean Leq levels at the laundry plant exceeded the 85 dBA action level recommended by the Occupational Safety and Health Administration (OSHA). Hence it can be concluded that laundry plants are hazardous occupational settings for hearing loss, thus preventive measures, such as hearing conservation programs must be adopted for the well-being of workers.

Determination of Traffic Induced Noise Pollution and Its Impact on The Citizens in The Zakho City Area

The current paper deals with determining the level of noise pollution in the area of ​​the Zakho city and its regions Impact on city residents. In this study, noise levels were measured with a digital sound level meter in seven different places in Zakho from 9:00 AM to 8:00 PM during working days. The time-weighted average noise level was measured on the roadside. The data collected was analyzed to calculate the average, maximum, and minimum noise level in decibels (dB) with respect to traffic volume. It was observed from the study that the highest roadside noise level in Zakho city was 96.1 dB found in the traffic (A) at the evening, which exceeded the acceptable limit of 60 dB set by the Government of Iraqi region and the minimum sound level of 51.5 dB was recorded in Traffic (D) area at the morning. The highest mean value is 88.63dB found in traffic (A) at the evening and the lowest median value is 66.5dB found in the Traffic (D) at the morning. During the study and according to Questionnaire survey, Noise health effects are the health consequences that high levels of noise have on health. It causes hearing loss, high blood pressure, and decreased blood flow to the heart, bowel movements, sleep disturbance, and an increase in work accident rates.

DESIGN AND TECHNOLOGICAL METHODS FOR REDUCING THE NOISE EMISSION OF TOOTHED-BELT TRANSMISSIONS

Design and technological methods of noise emission reduction in toothed-belt transmissions are considered. An improved method for selecting rational geometric parameters of drive toothed belts that ensure a minimum level of transmission noise has been developed.

Optical injection locking based local oscillator regeneration for continuous variable quantum key distribution.

We develop an optical injection locking (OIL) based local oscillator (LO) regeneration for continuous variable quantum key distribution (CVQKD) by sending a weak polarization multiplexed pilot carrier from the transmitter. The OIL at the receiver has superior performance in terms of minimum input power and noise level at offset frequencies to the erbium-doped fiber amplifier (EDFA)-based scheme. The weak pilot carrier is recovered both in power and phase via the OIL while incurring little excess noise to the CVQKD system. The phase-locked LO enables heterodyne detection of a Gaussian modulated quantum signal with a simple data-aided phase recovery without pilot tone. The obtained parameters are compatible with a raw key rate of 0.83 Mbit/s in the asymptotic regime over a 22-km fiber transmission. The technique is expected to be used in more phase-sensitive quantum optical applications.

Bitslice Masking and Improved Shuffling:

We revisit the popular adage that side-channel countermeasures must be combined to be efficient, and study its application to bitslice masking and shuffling. Our main contributions are twofold. First, we improve this combination: by shuffling the shares of a masked implementation rather than its tuples, we can amplify the impact of the shuffling exponentially in the number of shares, while this impact was independent of the masking security order in previous works. Second, we evaluate the masking and shuffling combination’s performance vs. security tradeoff under sufficient noise conditions: we show that the best approach is to mask first (i.e., fill the registers with as many shares as possible) and shuffle the independent operations that remain. We conclude that with moderate but sufficient noise, the “bitslice masking + shuffling” combination of countermeasures is practically relevant, and its interest increases when randomness is expensive and many independent operations are available for shuffling. When these conditions are not met, masking only is the best option. As additional side results, we improve the best known attack against the shuffling countermeasure from ASIACRYPT 2012. We also recall that algorithmic countermeasures like masking and shuffling, and therefore their combination, cannot be implemented securely without a minimum level of physical noise.

Schools Traffic Noise Pollution Levels Along Federal Roads in Muallim District, Perak, Malaysia

This article aims to identify the school traffic noise level along federal roads in Muallim District, Perak, namely SMK Khir Johari (SMKKJ), SMK Agama Slim River (SMKASR) and SMK Dato’ Zulkifli Muhammad (SMKDZ). Data were collected during school hours and on weekends, from 7 September to 13 September 2019 and three times a day, 7.00 -8.00 am, 9.00 -10.00 am and 12.00 -1.00 pm. Data was collected using Digital Sound Level Meter AS804, which was mounted on a tripod approximately one meter high from the road surface to prevent road sound reflection. Sound recordings were performed using decibel scale weights (dBA) and values for Max (Maximum Noise Level), Min (Minimum Noise Level), Leq (Average Overall Noise) with five minutes time delay and descriptive analysis. The findings show all stations values exceeded the standards set by the Malaysia Department of Environment (DOE) (60 dBA). SMKKJ shows the Min value is 57.7 dBA, the Max value is 94.5 dBA and Leq 76.1 dBA during working hours. In conclusion, the study showed that all stations recorded high noise during working hours and non-working hours surpass the standard set by DOE during the day. The need for the Malaysian Ministry of Education to assess and plan to reduce this noise level through short-term and long-term measures.