Volume 11, Issue 1

Rapid transit or mass rapid transit (MRT) is a high-capacity public transport designed to carry a large number of passengers, especially during the peak hours. They are becoming very popular in major cities and some deem the presence of the rapid transit system in a city as a symbol of modern development and essential feature of urban life. As the rapid transit system expands, the traveling time on a rapid transit train may increase due to longer journey and cabin noise has become an environmental concern for the passengers. In the present study, we would attempt to do a more detailed study of the effect of viaduct height, in particular viaducts of different heights on the cabin noise of various rapid transit systems. The present study examined and benchmarked the cabin noise in terms of both dB(A) and dB(C) for four different rapid transit systems, namely part of the East-West line including the Tuas-West extension on elevated tracks with very high viaduct of the Singapore MRT System; part of Paris Line 2 from Anvers to Belleville station including a stretch of elevated track on viaduct; part of the Piccadilly line of London from Heathrow Airport to Green Park station with a stretch on surface ground; and finally part of Chongqing Line 3 from Gongmao to Lianglukou station across the Yangtze river. It was found that the cabin noise would be dominated by low-frequency content and would be better reflected if the measurements were presented in dB(C), especially for trains running on elevated tracks of greater height.

Presented here is a constructive solution to the challenge of utilizing the diffraction phenomenon for mitigating noise around roadside objects caused by the movement of vehicles on transportation routes. In contrast to existing prototypes, the innovation of the proposed solution lies in the creation of an active system that concentrates and directs oscillations originating from transportation sources. This active system, centered around sound absorption and reflection, establishes protective barriers and focuses on sound vibrations. The incorporation of diffraction effects within the Fraunhofer zones, along with the utilization of Fresnel lenses, directs attention towards these vibrations. The technical objective of harnessing the diffraction phenomenon for noise reduction around roadside objects involves demonstrating the feasibility of using a Fresnel zone plate (FZP) tailored for a specific oscillation frequency. This plate should demonstrate the ability to effectively manipulate sounds of varying frequencies while retaining its diffractive focusing capabilities. The intrinsic frequency characteristics of diffractive elements cannot be eliminated due to the inherent nature of sound diffraction. Consequently, it is imperative to thoroughly investigate and account for these properties. A groundbreaking discovery has been made, confirming the phenomenon of noise concentration originating from transportation sources. This revelation suggests that when a FZP is employed at frequencies other than its designed frequency, the concentration of oscillations remains. However, only the focal point of concentration shifts. Through experimentation, it has been established that the same FZP can be employed for varying wavelengths within a range of approximately ±20% while adhering to diffraction conditions. The feasibility of employing the thin lens formula to focus oscillations following the passage through a FZP has been substantiated. This solution also delves into the principal focusing, frequency, and shaping characteristics of the diffractive elements within FZPs. Furthermore, a computed estimation of the acoustic field scattered by a diffraction grating is compared against experimental data. This validates the approach and its efficacy in practical scenarios. The potential of harnessing the diffraction phenomenon to concentrate and regulate noise from transportation sources, thereby safeguarding roadside objects, is presented as a promising avenue for exploration.

In densely populated cities, residents living near aerodromes may experience heightened exposure to aircraft noise. With hybrid work arrangement, authorities have observed a rise in the number of complaints filed by residents affected by aircraft noise. In view of this problem, urban planners are now placing even more emphasis on exploring solutions that can manage aircraft noise in new and existing residential areas. To achieve this objective, urban planners usually rely on external acoustic consultants to generate noise maps using commercial software. However, urban planners may need to quickly evaluate potential noise issues in the neighbourhood so that noise management strategies can be brainstormed in advance. In this article, we present the development and benchmarking of a package designed to easily generate aircraft noise maps via simplified procedures and a reduced amount of input data, with acceptable accuracy in the results. These benefits distinguish our developed package from commercial software. Our developed package was eventually integrated into an in-house-developed unified urban environmental modelling tool that aims to help urban planners design more liveable and sustainable residential towns in an intuitive and quick manner.

The sound qualities and wind speeds of the four commercial hair dryers (Panasonic, Confu, Flyco, and Philips) were investigated through experimental methods in the present study. The sound qualities included loudness, sharpness, roughness, and fluctuation strength. The experimental results showed that the maximum sound pressure level (SPL) of all hair dryers occurred at about 200 Hz except Flyco hair dryer, which occurred at about 400 Hz. The highest loudness and highest sharpness were found when the hair dryers were set to hot mode and cold mode, respectively. No consistent relationship was found between the effect of room space and SPLs of the hair dryers. The Box–Behnken design method was used to design 13 pieces of oval and rectangular nozzles, and their sound levels and wind speeds were measured. Thereafter, these experimental results were used to derive correlation coefficients between the hair dryer nozzle area, aspect ratio, nozzle length, loudness, and wind speed using the Anova analysis method. Finally, an oval nozzle and a rectangular nozzle with an area of 0.0005 m 2 {}^{2} , an aspect ratio of 1, and nozzle lengths of 0.052 and 0.055 m, respectively, were designed and were tested. These nozzles managed to reduce the sound loudness by 15 and 9.6%, respectively, while maintaining the same level of wind speed.

This study proposed a method to predict the future aircraft noise level of the international airport by taking Baiyun International Airport (BIA) as an example. BIA was selected to be studied because it is an important international aviation hub in China. The third phase expansion project of BIA is currently in progress, which is the largest airport expansion project in China. The method included the analysis of current operation of the airport, prediction of future operation scenario and operation of the airport, and predicted future population around the airport. Based on the predicted information, this study used CadnaA software to construct and analyze the noise maps of BIA during summer and winter in 2030. The major advancement of this study compared to that of previous research is that this study predicted the noise levels of the airport during summer and winter separately based on the wind direction of airport location, while other research did not take wind direction into consideration. It is found that operation Scenario 1 produces lower noise pollution level in the future compared to Scenario 2 based on the noise exposure results. It is worth mentioning that in 2030 during winter, when the noise level is greater than 70 dB, the noise-exposed area and population of BIA increase by 71.88 and 146.87% (Scenario 1), respectively, compared to current data, which is more serious compared to the growth rate during summer.

Noise from industrial plants, wind farms, ports, and airports ranges long distances and merges with noise from linear transport infrastructures ( i.e. roads and railways). A straightforward description of people’s long-term noise exposure is usually performed using simplified algorithms implemented in software packages. However, when focusing on the worst-case scenario in favourable sound propagation conditions, the prediction needs to be more accurate and requires the model’s calibration through actual measurements. In these cases, where the noise source under investigation, the concurrent sources, or all of them may be far away from the receivers, the correct choice of the temporal and meteorological windows to perform the measurements demands specific knowledge of weather-related phenomena. Such an approach is also essential in developing technically and economically sustainable mitigation strategies when required. This article first introduces some of the meteorological principles underpinning these phenomena. Within this framework, three of the most commonly used road-traffic noise calculation methods have been applied to identical scenarios, and their performances in accounting for weather-related effects on sound propagation have been analysed. The chosen methodological approach can be used for other environmental noise sources.

The present study analyzed the effect of noise annoyance due to road traffic based on a comprehensive socio-acoustics survey at a large number of sites in the NCT of Delhi. This study presents the development of exposure–effect relationships and noise annoyance models using the Structural Equation Modeling (SEM) approach. The study assesses the traffic noise annoyance caused by road traffic at various sites in NCT of Delhi, India. Exposure–effect relationships correlate the noise annoyance and traffic noise levels. The Structural Equation Model depicts the relationship between noise annoyance and various psychological factors. The effect of noise annoyance and awareness level was determined using a socio-acoustic questionnaire survey among the community of NCT of Delhi. The various parameters undertaken were demographic, honking, health impacts, and psychological perception. The developed PLS (Partial Least Square)–SEM model predicted that noise sensitivity and road traffic noise remarkably affected the noise-induced annoyance.

The aim of this study was to map and model the noise pollution level (NPL) of a highway in Iran by using statistical techniques, geographic information system (GIS) Software, and the Traffic Noise Model version 2.5 (TNM 2.5 ). The equivalent noise level in A weighting network ( L eq(A) ) was measured in 28 stations in different seasons using the sound level meter of the TES-1358 model. The traffic noise data and indices L eq (equivalent noise level), L max and L min (the maximum and minimum time-weighted noise levels), L n (noise pressure level exceeded for n percent of the time), NPL, and TNI (traffic noise index) were measured and calculated to determine the daily sound level. They were then statistically analyzed by SPSS and Sigma Plot Software. Finally, the GIS software and TNM 2.5 techniques were used to map and predict the traffic NPL in the region and the distribution of noise levels. The highest noise level was measured at about 80 and 79.61 dB in Kouhsangi and Abadgaran stations, respectively. The lowest level was measured at around 58 dB in the Hafez Square station. In addition, the results show that the highest and lowest L eq were almost in the same range (81–85 dB). It appears that the TNM 2.5 model can reasonably predict traffic noise levels as well as the dispersion and nature of noise pollution on the highway.

This study proposed a method of obtaining the type and quantity of equipment in factories by inquiring environmental impact assessment reports, which greatly improves the efficiency of gathering factory information. Thereafter, by combining on-site measurement and numerical modelling, the noise maps of an automobile industrial area were constructed. The exposed population under different noise levels were evaluated using the noise maps. The results indicated that noise pollution at nighttime in the study area was more severe than that during daytime, with 523 people (1.08%) and 1,357 people (2.81%) exposed to excessive noise levels during daytime and nighttime, respectively. In addition, this study also constructed a low-frequency industrial noise map. The methods and results of the present study can provide novel technical path for construction and analysis of large-scale industrial noise map.

Within the current urbanised society, the call for calm and quiet areas seems more pressing than ever. Such tranquil environments like the Woonerf streets in the Netherlands allow a more human-centred design, where traffic has a restricted speed limit of 15 km/h, while pedestrians and cars share the street without segregation. In the past, predictive models have been developed to assess the tranquillity levels based on indices related to noise exposure and the amount of greenery measured through the Green View Index. However, the urban environment encompasses multiple sound sources with people having different reactions towards the auditory stimuli. Because of this complexity, objective sound measurements are examined in combination with the subjective perception of noise through eight perceptual attributes. This is done by collecting audio and visual data in 61 Woonerf streets in the cities of Groningen and Leeuwarden, supported by additional questionnaire data gathered from the corresponding residents of the above-mentioned areas. Within the context of Woonerf streets, results indicate that sound levels are perceived as relatively pleasant and uneventful. Furthermore, a difference is observed between the predicted and subjective tranquillity.

This article systematically reviews research on noise pollution monitoring conducted over the past 23 years at various bus transit terminals located worldwide. About 18 articles were identified using PRISMA method and were evaluated to provide summary of prior research work to examine accuracy, authenticity, and reliability of noise monitoring results with respect to chosen methodology and extent of noise pollution at bus transit terminals. It examines important indicators of noise pollution and the analysis parameters such as noise sampling, noise descriptors, processing of acquired data, noise mapping, etc. , and compares it with the regulations and standard guidelines notably ISO 1996-2:2017 and American National Standards Institute/ASA S12.18-1994 (R2009) and their prior versions aiming to identify research gaps. The studies have primarily focused on noise monitoring, revealing widespread excessive noise pollution exceeding permissible levels at bus terminals globally. This article underscores significant research deficiencies in noise pollution monitoring at bus terminals, emphasizing the challenge of conducting quantitative meta-analyses and statistical comparisons due to variations in parameters and qualities. Noise pollution standards are breached in all terminals covered in the identified literature; hence, noise mitigation measures must be implemented at these bus terminals. The study suggests that noise monitoring must be carefully devised with respect to individual site operations and noise sources and in compliance with standard guidelines to improve the accuracy of the results. There is a need for uniform guidelines that can be followed globally for environmental noise monitoring as there are only a few countries that have guidelines for noise monitoring. The outcomes of this research will be helpful in guiding noise monitoring, mapping, and mitigation strategies as well as designing transit terminals to improve overall acoustical ambiance for more passenger footfall for sustainable transportation.

The Welsh Government’s policy on noise and soundscape is underpinned by two key pieces of legislation: the Well-being of Future Generations (Wales) Act 2015, and the Environment (Air Quality and Soundscapes) (Wales) Act 2024. The former established our national well-being/sustainable development goals and five ways of working that public bodies should follow in order to achieve them. The latter requires Welsh Ministers to set out their soundscape policies in a national strategy and requires public authorities to have regard to the policies in that strategy when carrying out their functions. The intent of this article is to raise international awareness amongst soundscape researchers as to how one devolved nation has incorporated the concept of soundscape in its policies and legislation and hopefully encourage the further development and dissemination of soundscape assessment and design tools that enable practitioners to better implement those policies.

A university campus is a complex environment, as it comprises many areas, each with distinctive acoustic characteristics. There are zones where a quiet environment is crucial for work and study, parking lots and internal road networks, as well as vibrant spaces where students and personnel stay during leisure time. Thus, university campuses clearly offer a remarkable opportunity for the evaluation of soundscape analysis tools and the exploration of new methodologies for assessing and mapping soundscapes. In this work, the Fisciano campus of the University of Salerno (Italy) has been depicted as a case study. Specifically, the outcomes of a soundwalk conducted following ISO/TS 12913 standards will be presented, together with data gathered through crowd-sourcing during NoiseCapture parties. The data from NoiseCapture parties have been used to test and validate an innovative methodology based on an inverse distance weighting interpolation to produce soundscapes’ attributes maps, using the mean pleasantness as an example and exploring the relative influence of the maximum distance used to characterize an homogeneous sound environment to build the maps themselves. The results will offer valuable insights into the proposed methodology.

High environmental noise as well as poor biodiversity and air pollution pose significant challenges for the European population, particularly those residing in urban areas, impacting clearly on citizens’ health. The Conscious Walk initiative stands for an innovative hybrid approach to analyse citizens’ perception of their environment. Being a citizen science participative project, Conscious Walks involves both citizens and scientists collecting high-quality acoustic, chemical, biodiversity, and comfort data while walking in pre-analysed urban environments. The main objective of this proposal is to obtain comprehensive data encompassing both subjective and objective aspects related to soundscape, air quality, biodiversity, and urban comfort. All these elements are closely tied to the overall acoustic environmental quality of the places under study. The effectiveness of this methodology has been tested in various locations in Catalonia, including Sabadell and Barcelona. This contribution focuses on the evaluation of the soundscape in the urban centre of Barcelona, with a comprehensive analysis that integrates data collected by both citizens and scientists during Conscious Walks, air quality metrics, biodiversity, and human comfort information.

In recent years, various stakeholders and political decision-makers have recognized the significance of high-quality urban sound environments, stressing the need for user-centered trajectories. Despite the rising interest in this field, the soundscape approach has not yet fully permeated urban planning and design, possibly due to a lack of comprehensible guidelines on how to implement and curate successful soundscape designs, attributed to on-going developments on this subject. In the course of the Catalogue of Soundscape Interventions (CSI) Project, a taxonomy of eight dimensions was developed to serve as an orientation aid for practitioners, describing important aspects of soundscape-related measures that can be used as a brief to facilitate communication between authorities, consultants, and researchers. This study describes the theoretical framework and, in particular, the sequential coding process involved in deriving these dimensions, which is based on grounded theory. It lists observations and limitations of the resulting taxonomy and builds upon these findings to critically review and revisit existing nomenclature and concepts. Finally, a qualitative distinction in the form of a design pyramid according to ascending levels of epistemic rigor is proposed, to differentiate between documented practices, which may serve as a reference point for future harmonization and standardization.

The hospital soundscape is known for high noise levels and a perception of chaos, leading to concerns about its impact on patients, families, professionals, and other hospital staff. This study investigates the relationship between sound, A nnoyance, and sleep quality in a multi-patient neurology ward. A mixed-methods approach was employed. Interviews were conducted with medical staff ( n = 7) to understand their experiences with sound. Questionnaires and sleep tracking devices ( n = 20) assessed patient sleep quality and A nnoyance caused by sound events. In addition, listeners ( n = 28) annotated 429 nighttime audio recordings to identify sound sources and rate A nnoyance level, which we considered the key emotional descriptor for patients. Over 9,200 sound events were analysed. While snoring, a patient-generated sound dominated the nighttime soundscape and was highly rated for A nnoyance, and staff-generated sounds such as speech and footsteps were found to contribute more to accumulated A nnoyance due to their extended duration. This study suggests that patient sleep quality can be improved by focusing on design interventions that reduce the impact of specific sounds. These might include raising awareness among staff about activities that might produce annoying sounds and implementing strategies to mitigate their disruptive effects.

In the field of urban design assessment, increasing attention to the nonexpert verbalizations is paid to engage social participation in planning processes, especially those not limited to static visual renderings. However, little has been explored on reproducible methods to collect these vocabularies and their relationship with architectural features. This study presents a hierarchical multifactor analysis to extract the main perceptual nonexpert clusters; and a linear correlation analysis to relate them with 2D isovist measures. In an on-line experiment, participants ( n = 20 n=20 ) elicited individual attributes ( n = 120 n=120 ) to describe their soundscape and visual perception and compared recorded urban environments ( n = 8 n=8 ). The results show that a percentage of nonexpert audio attributes correlate as well as the visual ones with isovist metrics.

Road traffic noise is the second largest environmental stressor in urban areas in Europe after air pollution. The harmful effects of noise arise mainly from the stress response it triggers in the human body, which can have significant consequences for physical and mental health. Therefore, the use of a reliable noise prediction model is an important prerequisite for the quality assessment of a number of residents exposed to excessive noise levels and for the selection of appropriate noise mitigation measures. In this study, the analysis of road traffic noise in an urban street in the narrower centre of the Croatian capital Zagreb was performed using four noise prediction models: "RLS-90", "RLS-19", “NMPB-Routes-96 (SET-RA-CERTU-LCPC-CSTB)”, and “CNOSSOS-EU”. LimA V2021 noise prediction software was used for the analysis, and the noise modelling results were validated with short-term noise measurements. The main objective of the research presented in the article was to test the “CNOSSOS-EU” method, recently introduced in Croatian noise control practice, and to gain initial insights into which of the aforementioned noise prediction models is the most reliable for the assessment of road traffic noise in urban environments in Croatia. A comparison of the noise modelling results with the results of short-term noise measurements has shown that the German national calculation methods “RLS-90” and “RLS-19” as well as the “CNOSSOS-EU” method provide significantly more accurate noise predictions than the “NMPB-Routes-96 (SETRA-CERTU-LCPC-CSTB)” method.

Environmental noise directive requires Member States to produce and periodically update strategic noise maps for agglomerates in order to evaluate citizens’ noise exposure before the action plan. Its ultimate purpose is to mitigate the highest or most harmful noise levels. Available tools do not provide a point-to-point indication of the predominant sources to be addressed by intervention on the sources by individual owners. Recently, noise source predominance maps were developed to show the predominant source at each point of the calculation grid of the strategic noise map by means of polygons and colors. Intensity noise source predominance maps were also developed to add the visualization of noise exposure levels by coloring the polygons according to a color scale. This work investigates their applicability in agglomerates and defines an additional indicator with the purpose of connecting the high levels of citizen exposure to its predominant source. The new approach provides an aid to administrations in identifying areas where singular noise mitigations would be truly effective in improving the citizen’s quality of life by ensuring a noticeable decrease in total noise while reducing exposure to the specific source.