Noise Management Research Articles

Providing acoustical advice for the purpose of strategic land-use planning

Strategic land-use planning is the process where stakeholders work together to design future land-use to achieve more desirable economic, social or environmental outcomes. There is often uncertainty around the type of acoustical advice required for the purpose of informing strategic land-use planning decisions. There are also limitations to the level of technical detail that can be made available when little is known about the nature or locations of potential future development. EMM Consulting Pty Limited’s experience in recent years has provided opportunities to work on various strategic land-use planning projects. This experience has enabled an understanding of what is required by relevant stakeholders to appropriately inform decisions as well as what is possible from a technical perspective. The importance of establishing clear expectations around technical outcomes and uncertainties is highlighted, as well as the importance of collaboration with all relevant stakeholders. A strong understanding of the planning framework the project will be approved and operate within is critical. The importance of having an appropriate authority and/or framework to facilitate the implementation of required noise measures and a plan to transition existing land use is discussed. The benefits and limitations of a Noise Management Precinct, as described in the Noise Policy for Industry (NSW EPA, 2017), are identified. Noise modeling methods and technical assumptions that could be utilized to predict and manage likely impacts are described.

A risk-based approach to precinct planning

As urban populations increase more people being affected by noise. Industrial precincts are a key component of the economy, but they are placed near existing resident. Planning is an important tool to manage the noise exposure from these areas. This paper describes the method we developed to help with deciding where noisy activities, and the amount of mitigation required, to reduce the risk of annoyance from the precinct. Our method is based on modeling the impact from a grid of sources overlayed on the precinct boundary. The transfer functions for each source to all sensitive receiver is calculated using a standard noise propagation model. An optimization algorithm is used to fairly calculate the maximum sound power for each grid point without exceeding the noise management levels. Risk maps are created using contours based on standard industrial sound power densities to define 3 zones: the central, intermediate, and interface. The risk maps are a useful tool for planners for deciding where to locate projects and the amount of mitigation required.

Low frequency noise study of entertainment venues

Noise impacts from entertainment venues have long been a challenge to communities, local government and venue operators. A study into the decay rate of low frequency music noise from venues was undertaken in the Entertainment Precinct of Northbridge, Western Australia, for the Department of Water and Environmental Regulation (DWER). A drone mounted measurement method was utilised to gain an understanding of venue noise emissions via roof elements, combined with on-ground measurements and software noise modelling. The aerial measurements proved effective at low frequency, allowing for a more comprehensive analysis of the ten venues assessed. While the study revealed several challenges and discoveries, the concept of aerial noise measurement was proven to be useful in this application. The findings will further contribute to the development of guidelines and recommendations for noise management in Northbridge, ensuring a better acoustic environment for residents and visitors while maintaining the viability of the venues in the area.

The comprehensive role of acoustic materials in healthy sustainable building design

In today's world, the acoustic performance of buildings is increasingly evaluated in tandem with its environmental, health, and well-being implications. Design choices related to noise management, speech privacy, speech security, and reverberation time not only influence the occupant's comfort but also impact the environment and the people involved in the construction process. As such, acoustic materials are pivotal in creating sustainable and healthy buildings. Beyond traditional acoustic considerations, broader aspects impacting occupants' experience, such as sensory perception and indoor air quality, must be evaluated. A significant emphasis is placed on biophilic design to foster a connection between the built environment and nature for enhanced well-being. Similarly, the environmental impacts of material choices and the transition to recycled products to reduce the industry's environmental footprint are essential considerations. Acoustic materials have a far-reaching impact on sustainable and healthy building design by addressing occupant comfort, experience, air quality, and the environmental implications of material choices. Moreover, a comprehensive approach to acoustic design and material selection can pave the way for a greener, healthier, and more sustainable future.

A current affair: worker perceptions of noise exposure and occupational hearing loss in Australian coal mines.

The objective of the online survey was to determine worker attitudes towards, perceptions on hearing loss, and management of workplace noise; and to identify barriers within current strategies that prevent effective management of hearing health in Australian mines. This cross-sectional study utilized a modified survey design, initially designed for use by Safe Work Australia for a broader study published in 2010. The survey questionnaire was made available online to volunteer participants, recruited with the assistance of State and National Health and Safety, and mining organizations. Volunteer participants were required to be proficient in English, be employed by an Australian underground or open cut mine, including coal processing plants; or work as a contractor on one of the specified mine sites. All mining employees, regardless of occupation, job title, and occupational hearing loss classification or status, were invited to complete the questionnaire. Almost 60% of respondents indicated that they had high noise exposure for than 10 yr or more, and have some trouble hearing, mostly associated with infrequent tinnitus. Nearly 71% of these workers believe that the noise control strategies in their workplaces are effective, but this mostly refers to the use of hearing protection devices. The results indicate that general knowledge on the cause and effect of noise exposure in the workplace is well understood. However, due to the long latency associated with the development of noise-induced hearing loss (NIHL), there is an issue urgency in terms of risk management. It is surprising that most of the respondents recommended more inspections and administrative controls, especially since most respondents were health, safety, and environment (HSE) professionals. HSE professionals should be advocating for higher order, more permanent solutions, and not purely administrative controls and personal protective equipment. These findings raise the question of whether there is a multifaceted working-culture issue that needs to be addressed, in combination with higher order control implementation.

Reductions in community noise levels in vancouver, Canada, during pandemic lockdown and association with land cover type

BackgroundUrban transportation noise is a major public concern because of its adverse effects on health. The determinants of urban noise exposure have not been widely explored but the “natural experiment” presented by the COVID-19 lockdowns presented a unique opportunity.This study examined the relationship between environmental characteristics and urban noise pollution during the COVID-19 related lockdown in Metro Vancouver, Canada, from March 21st to May 18th, 2020. MethodsWe used noise exposure data from the Vancouver International Airport (YVR) noise management program, comparing the noise levels during “Phase One” of the COVID-19 lockdown in 2020 to the corresponding time period in 2019 from 21 Noise Monitoring Terminals (NMTs) located throughout Metro Vancouver. We modelled the relationship between the change in noise level and the physical NMT environments, including land cover, and total length of roads at four different time periods (24Hr, daytime, evening and nighttime) and within three different buffer zones (100 m, 250 m, and 500 m). ResultsOf 59,472 hourly measurements of community noise, the 24-h noise level was reduced by an average of 2.20 dBA between 2019 and 2020. Higher proportions of greenspace, barren areas, and soil-cover around NMTs resulted in stronger noise reductions and higher density of building, pavement, and water weakened the amount of noise reduction. Proximity of high-volume traffic roads (highways) were associated with weaker noise reduction. ConclusionThe COVID-19 related lockdown was associated with reduced noise in Metro Vancouver, and the relative reduction depended on the types of the environment surrounding the NMT. Future research on the effects of urban environmental characteristics on geographic inequality in noise levels and health consequences of the COVID-19 related lockdown is merited.

A Review of Noise Management Practice in Nigeria

Technological advancement, modern systems of transportation, and an expanding human population have brought in their wake a disturbing situation of exposure to environmental noise. This paper was therefore written to create awareness about the expository effects and impacts of environmental noise pollution on the human population. The target population of interest was the Nigerian population. The key findings were linked and related to existing regulations in Nigeria and other countries to enable effective intervention strategies to reduce the harmful impact of noise pollution. Noise pollution was identified as contributing to the poor health of citizens and as a barrier to development and growth at the national level. By focusing on adverse effects and risk factors, the paper highlighted methods to promote the best interests of the vulnerable population. The paper also acknowledged the issue of industrial and environmental noise pollution from the perspective of its contribution to the economic growth and development of the country. Noise pollution was, therefore, required to be measured and controlled with the help of effective strategic laws. It would help reduce the negative effects on the economy and the vulnerable Nigerian population. This paper will be useful in anticipating future reforms that can reduce the considerable noise pollution and its negative impact on the population group

Potency of some economic variables affecting environmental quality in Nigeria

Environmental quality (EQ) is germane to achieving sustainable living on earth. To evaluate a related stimulus of EQ on area basis, a comparative analyses of economic factors that influence pollution in Iwo and Ibadan metropolis was carried out. Data for the study was generated through the administration of 700 structured questionnaires in total at both locations, out of which 165 and 473 were retrieved from Iwo and Ibadan respectively. The distribution of respondents in form of male gender, married status, tertiary education and household size of not more than 5 were 51.5%, 78.2%, 24.9% and 46.1% respectively for Iwo, while it was 38.5%, 81.0%, 28.6% and 48.8% in the same order for Ibadan. Economic factors analyzed were (1) Income (2) living standard indexed by the form of accommodation occupied (3) waste/noise management regimen (4) energy utilization (5) orthodox versus green economy adoption and (6) waste sorting capacity. Kaiser–Meyer–Olkin sampling adequacy and Bartlett’s test of sphericity admitted the data as factorable at p < 0.005. Results showed that three of the economic variables significantly explained the pollution status in Iwo and Ibadan. The variables in Iwo explained 59.3% of the factors and these are waste/noise management strategies (22.5%), living standard (18.7%) and green economy adoption (18.3%). 60.2% of economic impacts on pollution in Ibadan were explained by living standard (24.4%), green economy adoption (18.8%) and waste/noise management strategies (17.0%). Only two of the variables namely living standard, and green economy adoption were common to the two study locations, although, their importance and ordering varied. While waste and noise management were most significant in Iwo, the same variable had the least effect in Ibadan. Green economy adoption was least in Iwo but most significant in Ibadan. Thus, the economic factors influencing pollution in Iwo and Ibadan metropolis, though similar, may not be given a generalized weighting. In other words, analyses of pollution-related matters from the economic viewpoint should be location specific.

Multi-Faceted Analysis of Airborne Noise Impact in the Port of Split (II)

Given the increasing number of citizen complaints about port noise and the lack of relevant studies assessing resident exposure, the effects of port noise are gaining increasing public attention. It is especially significant in ports near residential areas, where excessive noise emissions can seriously impact the urban environment. This paper aimed to investigate the perceptions and attitudes of the population living near the cargo terminals in the Port of Split regarding the impact of port noise in the urban area, focusing on their health and standards of living. The research methodology included a questionnaire distributed in the areas where the residents are most affected by noise. In addition to conventional descriptive survey analysis, the authors used regression analysis and two-way ANOVA with the Tukey post hoc test as a parametric data analysis tool. The survey results showed the harmful effects of port noise on most set parameters, and perceived noise intensity for three different times of the day caused a high level of concern for the urban environment. In addition, the regression analysis results showed a weak and reverse dependency between the distance of the selected residences from the noise sources and the perceived noise intensity. These findings support the validity of the respondents’ perceptions and the credibility of the obtained results. The application of parametric data analysis revealed a lack of formal knowledge of residents about the effects of noise and a strong differentiation between groups based on the variables that determine the level of education of residents and their assessments of the noise intensity of the cargo terminal. However, the subjective impressions and the psycho-physical and emotional states of the residents need also to be included in the validation of the results. The obtained results will facilitate the adoption of noise management policies and implementation of noise abatement programs in the Port of Split.

Agglomeration of Novi Sad Strategic Noise Maps

The local governing unit of the City of Novi Sad issued a public procurement in 2021 for the first strategic noise maps for the territory of the Novi Sad agglomeration. The strategic noise maps were methodologically and in terms of content realized in accordance with the local regulations of the Republic of Serbia that were in effect, as well as the Directive EU 2015/996 (CNOSSOS - EU:2015) and Directive 2002/49/EZ (better known as "European Noise Directive – END") guidelines. Road traffic was specifically analyzed due to it being the dominant noise source in the agglomeration. During the realization of the strategic noise maps a noise model for road traffic was created, with more than 3.000 road sections, where a road section is a part between two road junctions for the entire traffic infrastructure, with parameters for the acoustic model defined from point-to-point along the section. A part of the traffic data was gathered through the Traffic Study of Novi Sad 2029, which encompassed the Transportation Model of Novi Sad – NOSTRAM Model [1], the realization of which was planned as part of the development of General Plan of Novi Sad until 2029. The calculations encompassed more than 70.000 buildings with 147.618 living units and 320.346 inhabitants on a total area of 137,96 km2. This strategic document is the first step in noise management and environmental noise assessment, the data of which is used as the basis for action plans for environmental noise protection through which noise reduction measures are defined.

Acoustic Dissipation and Modal Coupling in Server Computers

Interest in the interior acoustics of server computers is growing as noise generated by air movers (fans) is increasingly observed to impact the performance of hard disk drives (HDD) inside these computers. In a typical server, a backplane cavity is located between an array of air movers and an array of HDD such that the HDD may be within a fan diameter of the air movers. The possibility of functional degradation requires careful management of air mover noise with respect to HDD susceptibility to acoustic noise disturbances and motivates understanding the physical phenomena underlying the acoustics. A previous investigation demonstrated the importance of coherence between acoustic standing wave modes in the backplane cavity. In this paper server interior airborne acoustics are further investigated by focusing on acoustic dissipation and inter-modal coupling in the backplane cavity. Various dissipation models are developed and used in conjunction with a previously formulated modal cavity acoustic model to generate cavity transfer factors. The transfer factor predictions are compared to measured transfer factors to draw further insights into the physical phenomena governing the interior cavity acoustics.

An efficient calculation method of large-region dynamic traffic noise maps based on hybrid modeling

The construction of noise maps is of great significance for the management and control of urban noise and the protection of residents’ physical and mental health. The European Noise Directive recommends using computational methods to construct strategic noise maps when possible. The current noise maps based on model calculation rely on complex noise emission and propagation models, and their huge number of regional grids needs to consume a lot of calculation time. This seriously restricts the update efficiency of noise maps, making it difficult to realize large-scale application and real-time dynamic update of noise maps. In order to improve the computational efficiency of noise maps, based on big data-driven technology, this paper combines the traditional CNOSSOS-EU noise emission modeling method with the multivariate nonlinear regression modeling method, and proposes an efficient calculation method of large-region dynamic traffic noise maps based on hybrid modeling method. First, this paper constructs the (daily and nightly) noise contribution prediction models of road sources with different classes, considering the daily and nightly periods and different urban road classes. Parameters of the proposed model are evaluated by using the multivariate nonlinear regression method to replace the complex nonlinear acoustic mechanism modeling. On this basis, in order to further improve the computational efficiency, noise contribution attenuations of the constructed models are parameterized and evaluated quantitatively. And then, the database containing the index table of the road noise sources-receivers and the corresponding noise contribution attenuations is constructed. The experimental results show that compared with the traditional calculation methods based on acoustic mechanism model, the noise map calculation method based on hybrid model proposed in this paper greatly reduces the model computations of noise map, improves the efficiency of noise mapping. It will provide technical support for constructing dynamic noise maps of large urban regions.

GIS Based Urban Noise Pollution Analysis and Mapping: The Case of Antalya, Turkey

In this study, it is aimed to determine the urban noise level, to classify it according to the provisions of the relevant regulation, to map it using geographic information systems (GIS) and to develop physical and administrative suggestions for eliminating the noise above the threshold value. In this context, the city center of Antalya was chosen as the study area. This area was digitized, and its maps were produced with the help of remote sensing and geographic information systems. Then, the noise levels of the region were measured using a decibel meter, provided that it was evenly distributed throughout the study area, all measurement points were coordinated, transferred to the map and a database was created. Interpolation was applied based on the noise threshold values in the "Evaluation and Management of Environmental Noise" regulation in the national legislation, noise levels were classified and noise maps were produced. In accordance with the relevant regulation, land survey was carried out again for the regions exceeding the noise limit values, and the sources of noise were identified. In line with the results, physical and administrative solutions have been developed for the elimination of noise in the region.

Characterizing the information transmission of inverse stochastic resonance and noise-induced activity amplification in neuronal systems.

Purkinje cells exhibit a reduction of the mean firing rate at intermediate-noise intensities, which is somewhat reminiscent of the response enhancement known as "stochastic resonance" (SR). Although the comparison with the stochastic resonance ends here, the current phenomenon has been given the name "inverse stochastic resonance" (ISR). Recent research has demonstrated that the ISR effect, like its close relative "nonstandard SR" [or, more correctly, noise-induced activity amplification (NIAA)], has been shown to stem from the weak-noise quenching of the initial distribution, in bistable regimes where the metastable state has a larger attraction basin than the global minimum. To understand the underlying mechanism of the ISR and NIAA phenomena, we study the probability distribution function of a one-dimensional system subjected to a bistable potential that has the property of symmetry, i.e., if we change the sign of one of its parameters, we can obtain both phenomena with the same properties in the depth of the wells and the width of their basins of attraction subjected to Gaussian white noise with variable intensity. Previous work has shown that one can theoretically determine the probability distribution function using the convex sum between the behavior at small and high noise intensities. To determine the probability distribution function more precisely, we resort to the "weighted ensemble Brownian dynamics simulation" model, which provides an accurate estimate of the probability distribution function for both low and high noise intensities and, most importantly, for the transition of both behaviors. In this way, on the one hand, we show that both phenomena emerge from a metastable system where, in the case of ISR, the global minimum of the system is in a state of lower activity, while in the case of NIAA, the global minimum is in a state of increased activity, the importance of which does not depend on the width of the basins of attraction. On the other hand, we see that quantifiers such as Fisher information, statistical complexity, and especially Shannon entropy fail to distinguish them, but they show the existence of the mentioned phenomena. Thus, noise management may well be a mechanism by which Purkinje cells find an efficient way to transmit information in the cerebral cortex.

Rice stubble: cotton fly waste composites for acoustic applications

The comfort level of human being can be increased by effective noise management without damaging the external environmental resources. The burning of rice stubble particularly in rice growing Asian countries makes the situation bad to worst. Rice stubble deserve for an immediate solution of in product development for its sustainable disposal. Rice stubble, cotton fly waste were used to manufacture composite material to be used as acoustic panel. Rice stubble powder 60%, 70%, and 80%, cotton fly waste 20%, 30%, and 40% by weight, and polyurethane (PU) resin were used to manufacture composite as acoustic panels. The composites were tested for pore size, morphology, water absorbability, and noise reduction coefficient (NRC) mainly. Acceptable level of NRC and other features were achieved. This study will provide a new pathway to use the discarded challenging waste materials to manufacture wealth-generating products.

A Comprehensive Review of Noise Measurement, Standards, Assessment, Geospatial Mapping and Public Health

Noise pollution is an emerging issue in cities around the world. Noise is a pernicious pollutant in urban landscapes mainly due to the increasing number of city inhabitants, road and aviation traffic, industrial and construction activities, and appliances or machinery used in daily life. The objective of this paper is to present a comprehensive review of noise measurement, guidelines/standards, and parameters used in noise monitoring; noise assessment associated with the area characteristics and the violations of guidelines/standards; noise geospatial mapping in urban planning; and physiological and psychological effects of noise exposure on public health. The review results revealed that standard methodology was lacking in many of the reviewed studies for noise measurement in various land-use patterns, especially the duration of noise monitoring; noise levels exceeded the prescribed noise standards in almost every noise assessment study across the globe irrespective of land-use or designated zone, and are exhibiting rising trends particularly due to traffic-induced noise; the majority of the urban population has been exposed to the noisy environment and affected with significant physiological and psychological health impacts; noise geospatial mapping has demonstrated high potential in noise abatement and management; and marked drop in noise levels in an urban environment during COVID-19 lockdown period. Based on the review results, the present study has suggested some future research perspectives of noise abatement and management that include a focus on – methodical noise assessment with prescribed guidelines of noise measurement and standards; geospatial noise mapping of urban areas, and real-time information system; universal database management software (DBMS) such as SQL and Improvado to compile data in single storage that will allow multiple users to access data despite different geographical locations; awareness programs using multi-media approaches in urban areas; and strict implementation of noise laws and regulations, that leads to the development of advanced technologies, integrated strategies, and sustainable environmental planning to mitigate the menace of noise pollution.

The Lyre and the Lyric: Spanish Vihuelists and the Courtly Poetry of the Renaissance

This article provides a close examination of sixteenth-century vihuela books to understand the ways in which vihuelists affected courtly poetry in Renaissance Spain. Analysis of their cancioneros in the light of other poetry collections and accounts of the aulic life reveal aural and performative aspects of the production and consumption of poetry that otherwise would have remained hidden to literary studies. These aspects range from voice register of the singer to tempo and musical ornamentation, but also textual manipulation of ballads and sonnets—which they help popularize among courtiers—and management of noise and interruptions.

Deep Learning-Based Road Traffic Noise Annoyance Assessment.

With the development of urban road traffic, road noise pollution is becoming a public concern. Controlling and reducing the harm caused by traffic noise pollution have been the hot spots of traffic noise management research. The subjective annoyance level of traffic noise has become one of the most important measurements for evaluating road traffic pollution. There are subjective experimental methods and objective prediction methods to assess the annoyance level of traffic noise: the subjective experimental method usually uses social surveys or listening experiments in laboratories to directly assess the subjective annoyance level, which is highly reliable, but often requires a lot of time and effort. The objective method extracts acoustic features and predicts the annoyance level through model mapping. Combining the above two methods, this paper proposes a deep learning model-based objective annoyance evaluation method, which directly constructs the mapping between the noise and annoyance level based on the listening experimental results and realizes the rapid evaluation of the noise annoyance level. The experimental results show that this method has reduced the mean absolute error by 30% more than the regression algorithm and neural network, while its performance is insufficient in the annoyance interval where samples are lacking. To solve this problem, the algorithm adopts transfer learning to further improve the robustness with a 30% mean absolute error reduction and a 5% improvement in the correlation coefficient between the true results and predicted results. Although the model trained on college students' data has some limitations, it is still a useful attempt to apply deep learning to noise assessment.

Assessment of people’s perception of air quality in Phnom Penh, the capital city of Cambodia

Air pollution is one of the regional and global ranking environmental issues, and certainly, become worthy of attention in terms of health concerns. The aims of this study are to monitor and measure particulate matter (PM2.5), as well as to study the people’s perception of air quality and their willingness to contribute to controlling air pollution in Phnom Penh. Realtime data of PM2.5 concentration was monitored from October 2018 through January 2019 by using a light-scattering sensor in downtown Chamkar Mon, Tuoll kork, and Chraoy Changva districts which were the places remarked as highly trafficked. The design questionnaire on the perception of people on air pollution and air quality was assessed through an online form called the KoboToolbox application, using simple random sampling. PM2.5 concentrations ranges from 14.879 to 33.481 µg/m3. The concentration found, is obviously above the standard level of the Environmental Protection Agency (EPA) has set. The air quality becomes deteriorated, while participants’ subjective assessment of air quality mostly has a neutral opinion. They don’t seem to take careful attention to how air quality becomes which reveals a significant difference between people’s perceptions and reality. Most participants have a negative impression greatly on vehicles. Seventy-seven and a haft percent of participants recognize vehicles as the main pollution sources followed by industrial facilities, open burning, construction sites, and BBQ restaurants by 52.50 %, 25.83 %, 24.16 %, and 5 %, respectively. Haft of the participants (50.83 %) are unaware of what is sub-degree 2000 related to air quality and noise management still, 65 % of participants give a positive attitude concerning the willingness to report air pollution cases regardless of incentive. Nearly 80 % of participants utilize social media, Facebook to perceive knowledge and related information about air. The result of the survey questionnaire in this study will be an initiative for policymakers to enhance legislative on-air quality management. However, the collective responsibility of society and individual contributors play important role in air quality control measures. Government should educate people about the peak period of air pollution in the city, by educating them on how important prevention is on the Facebook platform.

Qluster: An easy-to-implement generic workflow for robust clustering of health data.

The exploration of heath data by clustering algorithms allows to better describe the populations of interest by seeking the sub-profiles that compose it. This therefore reinforces medical knowledge, whether it is about a disease or a targeted population in real life. Nevertheless, contrary to the so-called conventional biostatistical methods where numerous guidelines exist, the standardization of data science approaches in clinical research remains a little discussed subject. This results in a significant variability in the execution of data science projects, whether in terms of algorithms used, reliability and credibility of the designed approach. Taking the path of parsimonious and judicious choice of both algorithms and implementations at each stage, this article proposes Qluster, a practical workflow for performing clustering tasks. Indeed, this workflow makes a compromise between (1) genericity of applications (e.g. usable on small or big data, on continuous, categorical or mixed variables, on database of high-dimensionality or not), (2) ease of implementation (need for few packages, few algorithms, few parameters, ...), and (3) robustness (e.g. use of proven algorithms and robust packages, evaluation of the stability of clusters, management of noise and multicollinearity). This workflow can be easily automated and/or routinely applied on a wide range of clustering projects. It can be useful both for data scientists with little experience in the field to make data clustering easier and more robust, and for more experienced data scientists who are looking for a straightforward and reliable solution to routinely perform preliminary data mining. A synthesis of the literature on data clustering as well as the scientific rationale supporting the proposed workflow is also provided. Finally, a detailed application of the workflow on a concrete use case is provided, along with a practical discussion for data scientists. An implementation on the Dataiku platform is available upon request to the authors.