Environmental Noise Measurements Research Articles

Identifying optimal feature sets for acoustic signal classification in environmental noise measurements

Whatever the sound source to be evaluated, spurious events or unwanted sounds will always be present in environmental noise measurements. Spurious events are not characteristic of standard residual noise and must be removed prior to subsequent analyses. Currently, the removal step is deferred solely to the objective evaluation of the sound pattern and/or spectrogram by an operator. This results in the loss of many man-hours. Machine learning can be used to develop a tool capable of recognizing and removing spurious events in noise measurements. The tool must be able to account for various sounds, whether human-made or animal, and must be applicable to any environmental scenario. This is not a straightforward task, in fact if humans can easily distinguish between two sounds, such as a birds' chirps and a car passing by, based on prior experience, a machine may not be able to do so without apprenticeship. Therefore, a learning methodology must be constructed for the machine by establishing recognizable patterns. The aim of this paper is to identify the feature sets which allow the algorithm to differentiate spurious sounds in the best way. These features will represent the semantic value of the signal.

Partial equivalent sound pressure level as an approach to manage irrelevant sounds in environmental noise measurements

Residual sound and unwanted events are known factors affecting the accuracy of environmental noise measurements. ISO 1996-2 provides methods to manage these irrelevant sounds, for example by applying correction factors, but the methods require a degree of knowledge of the irrelevant sounds that is not always practical or possible to obtain when performing long-term measurements with unattended monitoring stations in complex urban soundscapes. While automatic detection of irrelevant sounds provides the required information, it also allows for new approaches not described in ISO 1996-2. In this paper, we discuss a metric called partial equivalent sound pressure level (Partial Leq), calculated after data samples with residual sound and unwanted events are identified automatically and replaced by project-specific values. Our hypothesis is that better estimates of equivalent sound pressure levels (Leq) can be achieved with this metric, compared with the general methods given in ISO 1996-2. Comparisons of results are presented, together with a discussion of applicability of the Partial Leq metric and experiences gathered from its use.

Technical specification IEC/TS 61400-11-2: measurement of wind turbine noise characteristics in receptor position - an overview

To facilitate the development of wind energy, a Technical Specification has been developed by the IEC project team PT61400-11-2, giving guidance on how to assess the noise characteristics from a wind farm in the surroundings through measurements and assessment at the receptor position. This includes physical characteristics like sound pressure levels, wind speed, amplitude modulation, tonality, amongst others. In writing the Technical Specification, the expert group intended to collect experience and knowledge from existing methods and standards. The TS is written as an operational guideline for conducting measurements for authorities and measurement institutes, tailored to the specific intentions of the measurements. It will be of particular interest in countries where no guidance on wind farm noise measurements is available but also in countries where guidance and legislation of environmental noise measurements may not be sufficiently adapted for wind turbine noise specifics. An overview of the content of the document will be presented along with the considerations and choices made during extensive discussions by the international expert group stemming from acoustic measurement institutes, wind turbine manufacturers, wind farm developer, site operators and academia.

Measurement and analysis of intra-urban environmental noise in Melbourne, Australia

Measurement and analysis of intra-urban environmental noise in Melbourne, Australia

Depressive symptoms of people living in areas with high exposure to environmental noise: a multilevel analysis

Exposure and damage caused by noise have been reported in many countries around the world. However, few nationwide studies explored the association of residential environmental noise with depressive symptoms, this study aims to examine this association. The Korean Community Health Survey at the individual-level and the Korean Environmental Noise Measurement Database at the regional-level were used. A total of 30,630 individuals were eligible for the analysis. Multilevel model framework was applied to account for the clustered structure of the regional-level data in which individual-level data containing demographic characteristics and health information were nested. As a result of the analysis, Individuals living in the highest environmental noise area had a 1.55 times higher likelihood of experiencing depressive symptoms than those living in the lowest environmental noise area (95% CI, 1.04–2.31). After stratified analysis according to depressive symptom severity, individuals residing in areas with the highest environmental noise exposure had significantly higher odds of mild (aOR, 1.46; 95% CI, 1.02–2.07) and moderate symptoms (aOR, 1.70; 95% CI, 1.00–2.91). In conclusion, the higher the residential environmental noise, the higher the possibility of mild-to-moderate depressive symptoms. Our findings suggest the need for continued attention to and management of noise pollution, which has the potential to adversely affect individual’s mental health.

Acoustic Requalification of an Urban Evolving Site and Design of a Noise Barrier: A Case Study at the Bologna Engineering School

The increase in new infrastructure development has raised closer attention to the environmental noise of new expansion areas. This study investigates the urban evolution of Terracini Street’s surrounding area in the Navile district, Bologna, Italy. In the last 20 years, this area has undergone various transformations, from a suburban industrial area to a new university and residential one. First, the morphologic and infrastructural characteristics of the site are established. Then, the existing regulations (acoustic, urban, and infrastructural regulations, whether local or national) are evaluated. Next, the results of environmental noise measurements are presented. Since a heavily trafficked infrastructure is very close to the occupied public area, noise limits are severely exceeded. A noise mitigation design stage follows, focusing on a novel noise barrier design. Specifically, particular attention is paid to the visual and ecological impact of the noise barrier on the area’s landscape, which must be representative of the new location of the School of Engineering. The sonic crystal technique is exploited to implement an effective noise barrier (average insertion loss of 10 dB(A) in the 200 Hz–1 kHz range), allowing air ventilation and visual transparency. This case study could further evolve using other acoustic metamaterial techniques or in different application sites.

Analysis of the Usefulness of Cheap Audio Recorders for Spectral Measurement of Environmental Noise

Environmental noise pollution is nowadays one of the most serious health threats. The impact of noise on the human body depends not only on the sound level but also on its spectral distribution. Reliable measurements of the environmental noise spectrum are often hampered by the very high price of top quality measuring devices. This paper explores the possibility of using much cheaper audio recorders for the frequency analysis. Comparative research was performed in laboratory and field conditions, which showed that, with some limitations, these devices can be useful in analyzing the frequency of environmental noise. This provides an opportunity for reducing the cost of noise analysis experimental work.

Status of the revision of ISO 1996-1 standard on the assessment of environmental noise

The international standard on "Description, measurement and assessment of environmental noise - basic quantities and assessment procedures" ISO 1996 Part 1 is a major international reference document that both inspires and is inspired by regional and national standards on noise assessment. It is supplemented by a number of standards including ISO 1996 Part 2 which deals with the determination of sound pressure levels, Part 1 defines the basic quantities to be used for the description of noise in community environments and describes basic assessment procedures. It specifies methods to assess environmental noise and gives guidance on predicting the potential annoyance response of a community to long-term exposure from various types of environmental noises. The current edition from 2016 is under revision, as an ISO "preliminary work item." This paper will explain why it was decided to revise the standard, what comments were submitted during the standard's systematic review, and the topics under discussion in the working group assigned by ISO to revise it. In addition, it will describe the process of revision within the ISO structure including the current development framework, the status of the revision and the planned next steps.

Horizontal-to-Vertical Spectral Ratios and Refraction Microtremor Analyses for Seismic Site Effects and Soil Classification in the City of David, Western Panama

The City of David constitutes one of the most important commercial centers of the Republic of Panama. However, it is located on a coastal plane, close to an area with high seismic activity and has been affected by significant earthquakes (18 July 1934, Mw = 7.4 and 12 March 1962, Mw = 6.7). The goal of this study is to estimate the seismic effects and to classify the soil in the City of David. The experimental work entailed the measurement of environmental noise for H/V spectral ratio (HVSR) analyzed at 22 stations. A series of microtremor refraction studies (ReMi) at six stations distributed from north to south of the city was also performed. The stations were distributed around urban areas of the city, which are characterized by the presence of water supply, sewerage, buildings, roads, etc. The spectral analysis of environmental noise allowed the generation of three different types of maps: First, predominant frequency maps (f0) with zones composed mainly of rigid and semi-rigid soils in the southern end of the city and rigid soils in the central and northern regions. Secondly, maximum H/V amplitude maps (A0) which evidence a low range of HVSR amplitude in the city, ranging from 1.1 to 3.8. Finally, liquefaction vulnerability (Kg) maps, with values less than 2 Hz−1, representative of a low liquefaction risk. Soil classification using ReMi and calculation of the corresponding Vs30 reveal type D soils, which correlate well with results obtained using HVSR analyses. A comparison between HVSR and ReMi shows that HVSR curves that exhibit clear peaks tend to be related to ReMi stations that presented relatively large shear-wave velocity contrasts at some depth. The results from this research are intended to aid the decision-making process related to the future development of the city, as well as government level maintenance and mitigation plans.

Results of study of environmental noise before, during and after COVID-19 period in conditions of Samara region of Russia and approaches to noise reduction

The acoustical pollution in conditions of urban territories is rapidly increasing and causing a negative impact to the population and to the staff of industrial enterprises. The sources of environmental noise generations are analyzed. Transport and industrial plants may be considered as the main noise sources in the city environment. New results of research of environmental noise in urban conditions before, during and after COVID-19 period on the Samara region of Russia are presented. Experimental results of noise measurements caused by traffic movement and industrial enterprises operation are discussed. Comparison of results of environmental noise measurements in urban conditions before and during COVID-19 period shows that transport noise level was reduced, but the industrial noise level was almost the same, especially in low frequency range. Approaches to reduction of increased environmental noise levels in urban conditions are suggested.

Long-term environmental noise measurement methods for industrial noise sources

Industrial noise sources can impact nearby residential communities, especially in rural areas. In order to assess the situation after commissioning, plant noise must be reliably differentiated from prevailing ambient, transient environmental noises, and weather-related events. Continuously attending such measurements is generally impractical. On the other hand, classifying events by eyeballing a stream of Leq values after the fact isn't sufficiently reliable in most cases either. An effective approach is presented that involves measurement and statistical, observational, and analytical methods to perform much of the work in an automated fashion. Methods include statistically excluding transients from the Leq, filtering to eliminate birds and bugs, spectral characteristics of wind events, and potential spectral identifiers indicative of operation. Classifications are confirmed by listening to periodic and/or event-driven audio segments. This approach works best when both the plant noise and prevailing ambient are quasi-steady; plant-generated transients and weather events may require manual reclassification. Examples from long-term environmental noise studies are provided. The methods are neither dramatic nor novel but their effectiveness in combination may be useful, especially for those new to this type of work.

Automatic tracking method for submarine cables and pipelines of AUV based on side scan sonar

Submarine cables and pipelines laid on the seafloor are critical infrastructures for energy transportation and communication transmission and must be inspected in a timely manner to determine maintenance needs. Autonomous inspection of cables (including pipelines) and their surroundings using underwater vehicles is difficult because of sensor myopia and deviations in cable routing. This study proposes an automatic cable-tracking method (ACTM) based on side-scan sonar (SSS) that endows autonomous underwater vehicles (AUVs) with autonomous decision-making capabilities to achieve fast localization and stable tracking of submarine cables with large uncertainties. Compared with the traditional predefined waypoint method, the proposed method decomposes the tasks into a series of independent behaviors according to operational objectives; thus, the AUV can perform online dynamic task replanning and realize an autonomous coverage search of the target region. When a cable is detected, the cable-tracking task is constructed as a path-following control problem on the horizontal plane. To reduce uncertainties caused by environmental noise and sensor measurement errors, a uniform motion model based on target tracking theory was used to model the virtual mass abstracted from the cable, and the states of the cable were estimated using the Kalman filter. Subsequently, an adaptive line-of-sight guidance algorithm for the SSS is established to dynamically adjust the look-ahead distance by introducing states such as cable curvature and angular change rate, which somewhat alleviates the tracking loss caused by the SSS short-sightedness. The proposed ACTM effectiveness and robustness were validated through numerical simulations and field tests. The results showed that the proposed method can achieve automatic search and adaptive tracking of cables, further reducing the role of humans in the task.

Geophysical Surveys for Geotechnical Model Reconstruction and Slope Stability Modelling

Performing a reliable stability analysis of a landslide slope requires a good understanding of the internal geometries and an accurate characterisation of the geotechnical parameters of the identified strata. Geotechnical models are commonly based on geomorphological data combined with direct and intrusive geotechnical investigations. However, the existence of numerous empirical correlations between seismic parameters (e.g., S-wave velocity) and geotechnical parameters in the literature has made it possible to investigate areas that are difficult to reach with direct instrumentation. These correlations are often overlooked even though they enable a reduction in investigation costs and time. By means of geophysical tests, it is in fact possible to estimate the N-SPT value and derive the friction angle from results obtained from environmental seismic noise measurements. Despite the empirical character and a certain level of uncertainty derived from the estimation of geotechnical parameters, these are particularly useful in the preliminary stages of an emergency, when straight data are not available and on all those soils where other direct in situ tests are not reliable. These correlations were successfully applied to the Theilly landslide (Western Alps, Italy), where the geotechnical model was obtained by integrating the results of a multi-parameter geophysical survey (H/V seismic noise and ground-penetrating radar) with stratigraphic and geomorphological observations, digital terrain model and field survey data. The analysis of the triggering conditions of the landslide was conducted by means of hydrological–geotechnical modelling, evaluating the behaviour of the slope under different rainfall scenarios and considering (or not) the stabilisation interventions present on the slope. The results of the filtration analyses for all events showed a top-down saturation mechanism, which led to the formation of a saturated face with a maximum thickness of 5 m. Stability analyses conducted for the same events showed the development of a shallow landslide in the first few metres of saturated soil. The modelling results are compatible with the actual evolution of the phenomenon and allow us to understand the triggering mechanism, providing models to support future interventions.

Localization of a remote source in a noisy deep ocean sound channel using phase-only matched autoproduct processing

Long-range passive source localization is possible in the deep ocean using phase-only matched autoproduct processing (POMAP) [Geroski and Dowling (2021). J. Acoust. Soc. Am. 150, 171-182], an algorithm based on matched field processing that is more robust to environmental mismatch. This paper extends these prior POMAP results by analyzing the localization performance of this algorithm in the presence of environmental noise. The noise rejection performance of POMAP is assessed using both simulated and measured signal data, with noise data based on environmental noise measurements. Herein, signal and noise measurements are from the nominally one-year-long PhilSea10 ocean acoustic propagation experiment. All signals were recorded from a single moored source, placed near the ocean sound channel 129.4 km away from a nearly water-column-spanning distributed vertical line array. The source transmitted linear frequency modulated chirps with nominal bandwidth from 200 to 300 Hz. The noise measurements used in this study were collected in the months after this source stopped transmitting, and synthetic samples of noise are calculated based on the characteristics of this measured noise. The effect that noise rejection algorithms have on the source localization performance of POMAP is also evaluated, but only 1 dB of performance improvement is achieved using these.

Comparison of soft ground and miscellaneous attenuation in pastureland of the American West

Environmental noise measurements were performed in American West pastureland including incremental measurements over soft ground and miscellaneous attenuation through thick willow brush. Measurements will be compared with standard prediction methods such as ISO 9613. Additional distant highway measurements complimented by an ambisonic microphone will also be discussed.

The Status of International Guidance and Standards for Environmental Noise Assessment

Since its first publication in 1971 of ISO/R 1996:1971 on Acoustics Assessment of Noise with Respect to Community Response, the International Organization for Standardization (ISO) has developed and published a range of standards for environmental noise assessment. The main ISO 1996 series of standards on Description, Measurement and Assessment of Environmental Noise has been developed in phases. And almost 30 years ago, ISO 9613 Attenuation of Sound During Propagation Outdoors was added. More recently, supporting standards such as the ISO PAS 20065 Objective Method for Assessing the Audibility of Tones in Noise and the ISO 17534 series concerning Software for the Calculation of Sound Outdoors have been added, and cooperation initiated with the International Electrotechnical Commission on the IEC 61400-11-2 Assessment of Wind Turbines Noise at receptor positions. This paper provides an overview of ISO standards related to environmental noise assessment. It also describes the historical development of the ISO 1996 series and related standards. Current developments, including their status, are described. Finally, it provides some suggestions and considerations for further research.

Environmental Noise Measurement Technique and Evaluation of Contribution of a Large Industrial Enterprise to Noise Pollution in the Neighboring Residential Area

Introduction: Strong influence of noise on the urban population is one of the problems of a large city. The main sources of noise include road transport, industrial enterprises, and construction sites. A combined exposure to various sources of noise impedes assessment of their effects on the population. Distinguishing one noise source from another is a difficult measurement task. Objective: To measure noise levels close to a large industrial enterprise given busy traffic nearby, and determine contributions of the industry and road transport to the noise situation in the neighboring residential area. Materials and methods: In summer 2022, noise levels were measured in the vicinity of a large industrial enterprise located in the city of Perm in the daytime and at night at seven and eight sites, respectively, using a sound and vibration meter of the “Assistant” series with an additional “Monitoring” mode. The subsequent processing of chronograms in the “Monitoring” software enabled us to distinguish the noise generated by the industry from that of road traffic using the “Cut” function that removes interferences. Processing of the results using the “energy subtraction” technique allowed quantification of contributions of various sources to the local noise pollution. Results: In this study, noise was measured in a residential area adjacent to an industrial enterprise and the obtained results are provided. Noise levels from the enterprise were determined using a specialized software. The calculated contributions to the noise environment in the residential area vary between 0.035 and 0.603. The conclusion is made about a possible effect produced by noise from the analyzed industrial enterprise on people living on this territory. Conclusion: The effect of industrial noise on people living close to industrial premises is significant only at nighttime.

Overview of technical certificate program from the Institute of Noise Control Engineering

Standards are often misunderstood by even the most seasoned of acoustic professionals, let alone new technicians and engineers in the field, as they are often very complicated, written in piecemeal fashion by committees and are updated often. Some of the standards even conflict with one another. To help alleviate this problem, the Institute of Noise Control Engineering (INCE) is developing two technical certificate programs designed to educate and evaluate participants on the details of common standards used in the noise control industry. Each program will contain education, testing, and continuing education on ASTM International and Acoustics Society of America (ASA) standards. The first program will cover general acoustical measurements and environmental noise measurements. The second program will cover field testing of building acoustics, including airborne and impact noise insulation as described in ASTM E336, ASTM E1007, and associated standards. The courses are currently being developed with a target launch date of early 2023. Comparisons to similar programs that have been developed in other countries will be included. A business case will be made on how these programs will save noise control engineering firms time and money in training new staff.

A novel approach to localization of environmental noise sources: Sub-windowing for time domain beamforming

This article brings a breakthrough in understanding the computation of direction of arrival (DOA) of sound waves and represents an important step in the further introduction of spatial domain into environmental noise and acoustics measurements in general. Instead of improving the accuracy of beamforming, it makes more sense to increase the number of DOA calculations in the time domain and to use the statistical properties of environmental noise to localise the noise sources. We know from experience that two noise sources never have the same frequency characteristics, operating times, and spatial locations. This is the foundation on which the presented research stands and is validated with experiments. The high frequency sampling of 192 kHz allows a subwindow approach to time domain beamforming and the subdivision of microphone signals into time intervals of less than one millisecond. This allows statistical analysis of the immission directivity during the typically used time constant of 125 ms. The calculation of DOA in the subwindows shortens the time needed to evaluate the contribution of each noise source to the total sound pressure level. This leads to more data points (immission vectors) and lower statistical error in environmental noise measurements. In this paper, we propose associating the temporal dominant direction with the temporal sound pressure level within the subwindow and integrating the results to determine the immission directivity. Numerical simulations, experiments and practical application of the sub-windowing differential beamforming algorithm (SubW-DBA) method provided promising results.

Research on the Environmental Impact of Industrial Noise Emitted By Mine and Mining Plants

Abstract The article presents the results of measurements of environmental noise accompanying the operation of devices operated in surface facilities of hard coal mines and noise generated in technological processes related to the loading and transport of spoil and materials necessary for production. The research results presented in the article are part of the program of “Consequences of excessive noise in the mining environment of hard coal mines”, the overarching goal of which is to reduce the emission of industrial noise. The research described in the article, carried out using the sampling method, was introduced in order to determine the actual values of noise levels emitted to the external environment from mines and mining plants, as well as to identify the acoustic power levels of devices and processes constituting the main sources of noise in mines. The obtained results showed that mines and mining plants are often not fully aware of the scale of the environmental impact of undesirable noise they emit. Therefore, the current periodic measurements of environmental noise should be replaced with permanent monitoring, which will be beneficial not only for the environment, residents of housing estates located near mines, but also for the mining plants themselves.