Noise Reduction Measures Research Articles

Sustainable reduction in sound levels on intensive care units through noise management - an implementation study

BackgroundThe noise levels in intensive care units usually exceed the recommended limits in (inter)national recommendations. Such noise levels can affect both the recovery of intensive care patients and the performance of staff. The aim of this study was to reduce ward-based noise levels in three intensive care units (anesthesiological, neurological, and neonatological).MethodsThe implementation of a setting-specific intervention bundle consisting of (a) ward-specific guide to noise management, (b) further noise reduction and prevention measures and (c) the use of “noise traffic lights” was evaluated in an implementation study with a pre-post design. Our primary endpoint was changes in sound level (equivalent continuous sound pressure (LAeq)) 12 weeks after the intervention, and the secondary endpoint was sound level (LAeq), peak sound pressure and maximum sound level at different time points, including changes at 24-week follow-up.ResultsAfter the intervention phase, we observed a significant overall reduction in the sound level of 0.77 decibels (A-weighted) (dB (A)), 95%-CI [0.06, 1.49], p = 0.034 with post-intervention measurements of LAeq1h 56.43 dB (A) compared to pre-intervention measurements of 57.21 dB (A). The difference was particularly large (2.21 dB (A) [p < 0.0001] in one of the three intensive care units. After adjusting our analysis for the intensity of nursing workload, the sound level reduction was smaller. Comparisons of LAeq1h between measurement times during the daytime periods showed a post-interventional difference of 58.28 dB(A) to 58.84 dB(A) baseline during the day of 0.57 dB(A), 95%-CI [-0.07, 1.21], p = 0.08 and at night of 53.36 dB(A) post-interventionally to 54.48 dB(A) baseline a difference of 1.11 dB(A) 95%-CI [0.19, 2.04], p = 0.02. In follow-up, baseline sound levels became realigned and we noted a rise in sound level of 0.81 dB (A) [p = 0.01].ConclusionsOur implementation study indicates that a bundle of interventions can reduce noise levels in intensive care units, although the clinical relevance of the measured effect must be questioned. Sufficient resources and a participatory approach using an implementation framework should therefore be employed to manage sustainable noise abatement.Trial registrationGerman Clinical Trials Register (DRKS): trial registration number: DRKS00025835; Date of registration: 12.08.2021.

PETAT — an ASIC for simple and efficient readout of large PET scanners

Modern PET scanners based on scintillating crystals use solid state photo detectors for light readout. The small area of these devices is beneficial for spatial resolution, but also leads to a large number of electronic channels to be read out, mostly by application specific integrated circuits (ASICs) containing amplification, noise reduction, hit finding, time stamping and amplitude measurement. Although each ASIC provides up to ≈ 64 channels, a large number of chips is required with the need for auxiliary electronic components like voltage regulators or FPGAs for control and data readout. The FPGAs in turn often require multiple supply voltages and configuration infrastructure, so that PCBs get complicated, cumbersome and power-hungry, in addition to the significant power requirement of the front-end ASICs. We address this issue in the latest generation of our PETA readout ASIC for SiPMs by a simplified control scheme and, in particular, by a hierarchical serial data readout which does not require any additional FPGA. In addition, it provides a time-sorted stream of hit data, allowing early on-detector data reduction and hit pre-processing like the removal of hits with no coincident partner. The simplicity of this readout facilitates a supply scheme where power/ground of multiple ASICs are connected in series instead of the standard parallel connection. This `serial-powering' approach can reduce supply current (while increasing overall supply voltage) so that voltage drop issues in the supply are alleviated.

Work-related temporary hearing loss and associated factors among textile industry workers in Amhara region, Ethiopia: a cross-sectional study

ObjectivesThis study was designed to assess occupational noise exposure levels, prevalence of temporary hearing loss and associated factors among textile industry workers in Amhara region, Ethiopia.DesignAn institution-based, cross-sectional study was...

Improving the quality of urban ecosystem through ecological soundscape management

Abstract In urban ecosystems, the interaction between humans and the environment is often dominated by noise from human activities, with the importance of natural sounds or the ecological soundscape being ignored. The ecological soundscape plays a crucial role in ecological interactions and the development of urban ecosystems by supporting biodiversity. Therefore, the impact of ecological soundscapes on enhancing sustainable ecosystems is aimed to be analyzed in this study. The influence of the ecological soundscape on the sustainability of living organisms in urban open spaces is evaluated, serving as an indicator for ecosystem improvement. Sound recordings were conducted at four strategic points. The dominant sound types are identified, and the role of the ecological soundscape in shaping soundscape patterns in urban open spaces is evaluated. Babakan Siliwangi Urban Forest was selected as the case study due to its significant benefits in improving the urban ecosystem. The results indicate that BSUF has not been fully taken over by the ecological soundscape. Natural sounds are masked by the constant human-made noise from traffic, indicating a decrease in biodiversity. Recommendations for enhancing the ecosystem through the ecological soundscape approach are provided, including noise reduction measures such as creating buffer zones with vegetation, expanding green spaces as habitats for wildlife contributing to natural sounds, and creating conditions supporting diverse flora and fauna. It is expected that these recommendations will lead to an enhancement of the ecological soundscape in urban areas and foster more sustainable and diverse ecosystems.

Retrofit Measures for Aircraft Noise Reduction: Simulation Benchmark and Impact Assessment

DLR, German Aerospace Center, has developed a low-noise retrofit to reduce noise generation of a conventional midrange transportation aircraft, i.e., measures to the airframe and engine exhaust nozzle. Selected measures have been installed onboard of DLR’s flying testbed Advanced Technology Research Aircraft and been subject to a flyover noise campaign. The aircraft in its original configuration and the modified aircraft have been tested and measured in flyover campaigns in 2016 and 2019, respectively. Initial simulation models have been derived from the results and previous component simulations and wind tunnel tests to account for the new reduction measures within DLR’s system noise prediction tool Parametric Aircraft Noise Analysis Module (PANAM). This paper presents the developed measures as selected for the flight test campaigns. An overview of the conducted flight tests is provided. The overall noise simulation process, including aircraft and engine design, flight simulation, and noise prediction, is presented. Simulation results obtained from this process are then compared to the measured levels from the flight campaigns. Estimated simulation uncertainties from PANAM can now be directly compared to differences between measured and simulated levels. Finally, a parameter study is conducted in order to assess the reduction potential of the novel retrofit measures along different simulated flight procedures. Spatial noise distribution in sound exposure level contours is assessed.

A systematic evaluation of helicopter cabin noise: Case study of Robinson R44 RAVEN II

A systematic evaluation of helicopter cabin noise: Case study of Robinson R44 RAVEN II

Effectiveness of noise barriers in sensitive urban areas: a comprehensive study on noise reduction strategies and public health implications.

This study investigates the effectiveness of noise management strategies, focusing on installing barriers to reduce urban noise pollution, particularly around hospitals. The research in Sakarya, Turkey, employs comprehensive noise measurements and modeling techniques to evaluate barrier interventions. The study included 24-h noise averages and specific measures for daytime, evening, and nighttime noise levels, using SoundPlan software for modeling and mapping. Results reveal that noise levels frequently exceed international thresholds, especially in high-traffic areas. However, introducing noise barriers significantly reduces noise levels, particularly at specific measurement points, demonstrating their effectiveness. This underscores the crucial role of noise management strategies in sensitive urban areas and highlights the urgency for proactive interventions to manage noise pollution. The study identifies the need for future research, including long-term studies to assess noise barriers' durability and sustained effectiveness, and the integration of other noise reduction measures such as green infrastructure. Practical applications of this research include informing urban planners and policymakers about effective strategies for mitigating noise pollution and improving public health. In conclusion, this study provides valuable insights into urban noise management by empirically demonstrating the effectiveness of barrier interventions in reducing noise pollution. It underscores the importance of proactive measures to protect human health and preserve environmental balance in sensitive urban areas. The findings advocate for the broader implementation of noise barriers and other complementary strategies in urban planning to enhance the quality of urban life.

The development of a new technical regulation on acoustics in buildings in Croatia

Even though Croatia gained its independence 32 years ago, up till now its legislation has not regulated the requirements that concern the acoustics in buildings. Instead, the regulations inherited from the former state of Yugoslavia were left in effect and have remained in use even after they were officially withdrawn, as no new regulations were adopted to replace them. To address this issue, a committee has been formed of experts affiliated with relevant governmental and professional organizations, and representing their respective fields of expertise, with the task of developing the new Technical Regulation on Acoustics in Buildings in Croatia. This document is to set detailed technical requirements on sound insulation as the means of protection from outdoor and indoor noise, the maximum permissible levels of indoor noise caused by service equipment, and the room acoustics design criteria for achieving optimal acoustics and/or as a noise reduction measure, to be partly or fully applied to a wide range of public and privately-owned buildings, with exceptions such as dedicated performance venues like concert halls or theatres. This paper presents the motivation for creating this document, its scope, and key aspects, as well as a brief overview of similar endeavors in the past.

Study on near-field noise control of stationary equipment

The noise of stationary equipment is usually controlled by the sound insulation shield with the mufflers. However, there is not enough space for the installation of the sound insulation shield in certain places or working conditions, so the noise reduction measures are difficult to apply. The noise control measures at the near-field of stationary equipment, especially those infinitely close to the surface of the equipment, can solve the problem of insufficient installation space. At this time, it is necessary to design a structure of noise control measures to ensure that it have sufficient noise reduction performance. In this paper, a noise reduction structure is designed for near-field noise control of stationary equipment. The experimental results show that the structure have a good noise reduction effect in the certain frequency range. The effective noise reduction frequency can be specially designed according to the frequency characteristics of different sound sources. In addition, a modular installation structure was designed.

Vibration and noise reduction on a cover for power electronics for electric vehicles with vibroacoustic metamaterials

Electric vehicles represent a particular challenge in terms of noise, vibration and harshness, since there is no masking of the combustion engine anymore. For consumer acceptance, long distances need to be covered with electric vehicle, which makes lightweight structures necessary. Consequently, vibration problems occur during operation, as lightweight structures are more susceptible to vibrations. Common measures for vibration and noise reduction add a considerable amount of mass to the vehicle, counteracting the lightweight efforts. Vibroacoustic metamaterials as a novel approach promise greater vibration reductions than common measures like Alubutyl or bitumen and are accompanied by a lower weight. This study deals with the design of vibroacoustic metamaterials for the noise and vibration reduction of a cover for power electronics of an electric vehicle. The design process is demonstrated for two different kinds of vibroacoustic metamaterials made from sheet metal and a plastic film. The structural dynamic behavior of both approaches is experimentally investigated and compared with a cover equipped with Alubutyl. The vibroacoustic metamaterial, which is made from sheet metal, is furthermore tested in a vehicle under driving condition. A reduction of tonal noise components by 11 dB is achieved within the passenger compartment.

Noise reduction design of new residential buildings along urban roads-taking a residential district in Foshan as an example

Taking a residential district in Foshan along the city road as an example, the impact of urban road traffic noise on it is studied. Firstly, the data is monitored in the noise field, then three-dimensional simulation models of residential buildings and road distribution are established in Cadna/A software, and noise simulation prediction is carried out according to the actual situation and relevant norms and standards. The predicted noise values of the exterior surface of residential buildings are obtained, which has exceeded the permissible interior noise level for residential buildings. By comparing the application effects of noise reduction measures in buildings, the noise reduction design scheme of new residential buildings along urban roads is finally proposed: the sound insulation doors and windows that meet the requirements are adopted. After the completion of the house, the indoor background noise and the sound insulation performance of the doors and windows are measured. The measured results show that the selection of sound insulation doors and windows is suitable and the indoor noise environment meets the design requirements of noise reduction. The results are helpful to provide technical reference for the noise reduction design and renovation of other residential buildings along urban roads.

Estimation of population exposed to road traffic noise in Kosovo highway using GIS modelling and roadside measurements

New highways have been introduced into Kosovo landscape in recent years. The trajectory of the highways crosses through the fields and in the middle of some previously remote rural settlements. This has changed the environment for these areas and the environmental noise is a major concern. This study aims to estimate the population exposed to high traffic noise levels around the highway routes in Kosovo. GIS has been used to model the highway lines, the terrain and the buildings on site. Roadside traffic noise measurements as well as traffic flow measurements have been conducted to approximate the noise sources. An approximate noise map has been generated for the studied area. The population exposed to daytime and nighttime road traffic noise were estimated. The results show the need for road traffic noise reduction measures and areas where they are most needed.

Handling of porous road surfaces in traffic noise calculations with Nord2000

Using porous road surfaces can be an alternative to more traditional noise reduction measures. Two factors contribute to the fact that road noise can get lower than with a conventional dense road surface: the rolling noise emission decreases, and the sound-absorbing road surface can further reduce the level. In a traffic noise calculation with Nord2000, the influence of the road surface on the sound emission is specified using road surface corrections while the acoustic surface impedance of the road surface determines the ground attenuation. However, due to measurement technical reasons, porous road surface corrections will include some (undesirable) ground attenuation, leading to that the rolling noise emission might be underestimated. Another problem is that the impedance model in Nord2000 (Delany &amp; Bazley) does not give correct results for porous road surfaces. These complications have been investigated with Nord2000 calculations using a program code extended to also include an impedance model capable of handling porous road surfaces (Hamet et al). The results have been used to formulate official Swedish recommendations on how porous road surfaces can be handled in traffic noise investigations with Nord2000.

Assessment of the effectiveness of ship machinery noise reduction measures using a test platform in a water basin

Assessment of the effectiveness of ship machinery noise reduction measures using a test platform in a water basin

Research on the Calculation Method and Influence Law of High-speed Railway Line Sound Source Propagation Attenuation Caused by Building Sheltering

Abstract In recent years, China’s rail transit system, particularly the high-speed railway network, has experienced rapid development. However, the issue of noise pollution along these railways has become increasingly severe. The accurate prediction of sound levels at specific points near buildings is challenging due to complex factors such as differences in line height, distance, and angle relative to the building. To address this challenge and improve predictions of sound propagation attenuation caused by building shelter from high-speed railway line sources, this study derives an integral expression for diffraction attenuation based on Curze and Meakawa’s point source acoustic diffraction theory. Numerical calculations are conducted to investigate the sound propagation attenuation patterns under different position relationships between buildings and railway lines. Field tests are also carried out along a high-speed railway in China. The findings are as follows: (1) The calculated results show a difference of less than 0.5 dB compared to measured values, indicating that they accurately reflect sound attenuation caused by building shelter. (2) The angle between the building and the railway as well as the distance between the sound point and the edge of the building significantly influence building shelter attenuation; with angle being most prominent among them within a frequency band of 500~2000 Hz resulting in an attenuation range of 0.6~15 dB variation should be considered when predicting noise levels at sensitive points or designing vibration and noise reduction measures accordingly. (3) Different distances between buildings and railway lines result in additional effects on attenuations.

Analysis of noise reduction in natural gas pressure-boosted power generation equipment

Abstract To address the issue of excessive noise from the natural gas pressure-boosted power generation equipment, this paper conducts a noise analysis on the equipment at a natural gas purification plant in the Southwest oil and gas field. It identifies the primary sources and mechanisms contributing to the noise from the pressure-boosted power generation equipment. The paper clarifies the effectiveness of the existing noise control measures. It proceeds to conduct indoor experimental research on the noise reduction effects of different combinations of sound insulation and absorption materials. It selects optimal noise reduction strategies suitable for different frequency spectra of noise sources and proposes recommendations for noise reduction measures. Additionally, it employs CadnaA software to simulate and validate the noise reduction effects.

Measured outdoor-indoor noise reduction through various open window sizes

Quantifying the effect of window openings on composite noise reduction of building façades is useful for evaluation with respect to noise regulations that prescribe indoor sound level limits with open window conditions. There are historical documents that indicate overall sound level reductions of open and closed windows, but there is little data available in octave band or one-third octave band resolution, or on the effect of the opening size. A series of Outdoor-Indoor Noise Reduction measurements were performed on a residential façade with closed-window and various open-window configurations. The test room was normally furnished with an approximate room volume of 64 m3. The open window areas ranged from approximately 1 to 13% of the total façade area. In addition to presenting one-third octave band results, the overall noise reduction ratings were computed using the reference sound spectrum from ASTM E1332. The overall noise reduction results show a trend of higher reduction with smaller open window area as expected. The results of the measurements also show that the slope of the trend varies with frequency.

RESEARCH OF THE NOISE LOAD OF VEHICLES

Noise can be viewed as an undesirable component of a signal that can affect the quality of perception or transmission of information in a system. In different contexts, the term «noise» may have different meanings, but a common feature is the random impulsive nature of this phenomenon. Automotive noise is sound energy generated by the movement of a vehicle and its components. The study of road traffic noise is an important area, especially in environments where noise can have a significant impact. This includes analyzing noise levels, identifying noise sources, assessing its impact on the environment, and developing strategies to reduce noise. This study analyzes the causes of automobile noise and their noise sources, and provides classification features. The research methodology included measuring the noise level at different points of the bus interior using a specialized acoustic sound level meter Testo 816. The Sound Meter program was additionally used to obtain current time values of noise level changes with graphical data interpretation. When the bus is idling, a monotonous noise load level in the range of 58-63 dB is observed in the cabin, which is typical for a running diesel engine, which is the main source of noise. The movement of the bus in urban conditions is accompanied by a change in traffic conditions, which in turn increases the maximum noise load to 73 dB. The movement of the bus in the city is accompanied by an increase in the noise load up to 74 dB and the equivalent up to 67 dB. This is due to an increase in speed, contact of tires with the asphalt road, interaction of the air environment with bus elements, the appearance of vibrations and other noises.Although the noise load in the bus interior is within the upper permissible limits, it requires the introduction of noise reduction measures, especially for long-distance buses for a comfortable ride for passengers. Therefore, it is important to take noise levels into account when designing and operating vehicles, as well as when planning urban infrastructure projects.

Analysis and control measures of vibration and noise sources in urban rail transit under the perspective of standard governance

With the rapid and large-scale development of rail transit engineering in China, the vibration and noise problems caused by rail transit operations are increasingly receiving widespread attention from all sectors of society. This paper is based on literature research and comprehensively analyzes the vibration and noise sources of urban rail transit. It systematically analyzes the composition, characteristics, and causes of vibration and noise in rail transit, and provides systematic governance measures for vibration and noise reduction in rail transit from two aspects: noise sources and propagation paths. The research results of this article have significant reference value for the engineering practice of vibration and noise reduction in rail transit.

Analyzing the impact of flexible shells and sound absorbent lining on acoustic wave behavior in ducts

This study focuses on investigating the propagation of acoustic waves in a cylindrical waveguide with higher‐order derivative‐based boundary conditions and a sound absorbent lining. The mode‐matching method is employed to solve the governing boundary value problem, utilizing continuity conditions for pressure and velocity at waveguide interfaces. The objective is to establish a theoretical framework for analyzing and optimizing the acoustic performance of the waveguide, considering the influence of crucial parameters. The study's findings hold significant practical implications in acoustic engineering and noise control, enabling accurate prediction of acoustic wave behavior and facilitating the design of effective noise reduction measures and optimized sound‐absorbing materials in various applications. Additionally, the numerical techniques developed here can be extended to address more complex waveguide geometries and boundary conditions.