Equivalent Continuous A-weighted Sound Pressure Research Articles

Forecasting an urban sound model using space syntax theory in three different urban patterns in Egypt

The objective of this study is to investigate an acoustic environment based on spatial configurations. To achieve this objective, two types of data were utilized. First, the urban acoustic data was collected from 96 measurements based on equivalent continuous A-weighted sound pressure levels across three different urban areas in Cairo, Egypt, during weekends and at night. The data was plotted on a contour map in an effort to investigate their distribution in the urban area. Secondly, the data was collected using DepthMapX software, and in this way, spatial analysis was produced with diverse spatial attributes. Moreover, on-site observations of pedestrian and traffic rates were made, and land use distribution was observed.Statistical analysis was also conducted using the Statistical Package for Social Sciences (SPSS). Our statistical analysis showed that the value of sound pressure level (LAeq) is greatly influenced by spatial attributes in highly accessible spatial configurations, with Normalized Angular Integration (NAIN) being the most accurate predictor of sound pressure level. Our findings also verified the existence of a high correlation between commercial and mixed land uses and (LAeq).Additionally, this study revealed that the urban sound model can predict sound pressure level (LAeq) in an urban setting. This dataset functions as a valuable resource for future research, urban designers, and policymakers who are addressing sustainable issues pertaining to soundscape, noise pollution, and urban planning.

Acute effects of military aircraft noise on sedative and analgesic drug administrations in psychiatric patients: A case-time series analysis

BackgroundExisting evidence suggests that psychiatric patients are highly noise sensitive, and that noise exposure increases the risk for adverse mental health outcomes, such as psychiatric hospitalizations and even suicide. To investigate acute effects of noise in this vulnerable population, we assessed short-term associations between fighter jet noise and on-demand sedative and analgesic drug administrations in a psychiatric clinic located close to a military airfield in Switzerland. MethodsWe applied a case time series analysis with an hourly time resolution using distributed-lag models. Analysis was adjusted for long-term and seasonal trends, day of week, time of day, time-varying weather conditions and the week of stay. Noise exposure (hourly A-weighted equivalent continuous sound pressure levels (LAeq)) was modelled using detailed flight plans and noise footprints for different fighter jet and route combinations. Outcome data were available from the clinic’s records. OutcomesDuring the study period (06/2016–12/2021), 23,486 flights occurred. 5,968 clinical stays with a median length of 41 days (IQR: 28d, 50d) were recorded. The odds ratio (OR) for medication administration over the lag period of 3 hours after exposure was 1.016 (95 %CI: 1.006, 1.026) per 10 dB LAeq for sedatives and 1.032 (95 %CI: 1.016, 1.048) per 10 dB for analgesics. Effects were larger in multimorbid patients. InterpretationCase time series analysis is a novel method to investigate transient associations in observational data while minimizing risk of bias. Using an objectively recorded outcome measure, our results demonstrate that psychiatric patients are a vulnerable population, in which noise exposure can lead to symptom exacerbations and adverse events.

Psychological and physiological evaluations of time-varying noises produced by air conditioners

Air conditioners are widely used in buildings to maintain thermal comfort for long time. Air conditioners produce sounds during operation, and air conditioners are regarded as one of the main noise sources in buildings. Most sounds produced by the air conditioner do not fluctuate over time and sound quality of the steady sounds produced by the air conditioner have been evaluated. However, air conditioners sometimes produce time-varying noises. Customers criticizes such noises are annoying when they sleep and they spend time quietly in the living room. The aim of this study was to determine the factors that significantly influence the psycho-physiological response to the time-varying noises produced by air conditioners. We assessed the A-weighted equivalent continuous sound pressure level (LAeq) and factors extracted from the autocorrelation function (ACF). Subjective loudness, sharpness, annoyance, and electroencephalography (EEG) were evaluated. Relationships between psychological and physiological responses and physical parameters, LAeq, the ACF factors, and their standard deviation, were determined. The LAeq and peak of the first maximum peak of the ACF were identified as significant factors for the time-varying noises.

Environmental controls of air-conditioned noise with the aid of the Psychoacoustics Perception Scale (PPS)

It is known that an air-conditioning system is an essential component of modern buildings for maintaining good indoor environmental quality. However, the adverse effect due to air-conditioned noise can offset its benefits. Although several noise indices such as Noise Criteria (NC), Noise Rating (NR), Room Criteria (RC), and A-weighted equivalent continuous sound pressure level (LAeq) have been developed to assess the acceptability of indoor noise environments, the noise feature of the environments and its psychological impacts on the occupants are not comprehensively evaluated. Psychoacoustics Perception Scale (PPS) is a psychometric tool to assess the psychological impacts about general judgment (Evaluation, E), sensitivity to the magnitude (Potency, P), and sensation of the temporal and spectral compositions (Activity, A) of noise on occupants. This study aimed to evaluate the air-conditioning building environments by using the traditional noise indices, psychoacoustic metrics, and the PPS. The significant correlations were found between the objective and subjective data. The results of the study provided the useful knowledge on future designs of the environmental controls of air-conditioned noise.

Variations in sound environment in an urban apartment building: A case study during and after the COVID-19 lockdown

Quiet communities, which are encouraged to maintain a harmonious and tranquil urban living environment, have attracted increasing attention in designing method in recent years. The relevant residential standards specify quiet thresholds with regard to noise pollution issues. However, the variation in height across floors of high-rise buildings and variation with time in sound environments have not been examined in detail. The city of Shanghai experienced a city-wide lockdown to control the spread of COVID-19, showing evidence of quietness and a significant reduction in anthropogenic noise. Here, we conducted noise monitoring in a 14-storey apartment building that was surrounded and shielded by other buildings in a typical urban community during and after the lockdown. The mean value of all 14 floors of equivalent continuous A-weighted sound pressure level (LAeq,T) after lockdown was systematically greater than that during lockdown, with differences of 3.6 and 3.1 dB during the daytime and night-time periods, respectively. We suggest that in practice, it is useful to consider the specific floor or time of day.

Sound Environment during Dental Treatment in Relation to COVID-19 Pandemic

This study delves into the acoustic environment within dental clinics, particularly focusing on the impact of extraoral suction devices employed for infection control amid the COVID-19 pandemic. The research encompasses a comprehensive investigation, including a questionnaire survey of dental professionals, sound level measurements at suction device openings, acoustic imaging, and a detailed analysis of sound levels and their spectral characteristics during dental procedures. Additionally, ambient sound levels within clinical settings were monitored over two consecutive days. The findings reveal notable observations. Dental professionals expressed concerns regarding increased sound levels and associated distress caused by extraoral suction device operation. Objective measurements identified varying A-weighted sound pressure levels ranging from 86.0 dB to 96.7 dB at suction device openings, highlighting elevated sound pressure levels and a wide frequency range, especially in the vicinity of both the dentist and the patient’s facial area during dental aerosol procedures. On the other hand, for the entire clinical room, the equivalent continuous A-weighted sound pressure level during the consultation hours was not considered problematic. In light of these findings, it becomes evident that there is a pressing necessity to refine the acoustic characteristics of extraoral suction devices to foster a more accommodating acoustic environment for both patients and dental healthcare professionals within dental clinics.

Effects of Audio-Visual Environmental Factors on Emotion Perception of Campus Walking Spaces in Northeastern China

In the context of urban sustainable development and the creation of pedestrian-friendly campus environments, optimizing campus walking spaces has emerged as a central focus in urban planning research. Presently, research in pedestrian environments predominantly adopts a macroscopic perspective, offering limited insights into pedestrians’ subjective experiences and emotional perceptions at a micro level. Therefore, this study conducted on-site experiments in 21 walking spaces across three campuses, utilizing image semantic analysis, multifunctional sound level meter, wearable electrocardiography devices, and the Profile of Mood States (POMS) to collect data separately on audio-visual environmental factors and pedestrians’ emotional states. This study’s findings revealed significant correlations (p < 0.01) among factors such as the Green Visual Index, Spatial Enclosure Index, Sky Visibility Index, Spatial feasibility Index, and Equivalent Continuous A-weighted Sound Pressure Level with physiological and psychological alterations in pedestrians’ emotions. Additionally, the various proportions of audio-visual environmental factors also exerted significant influences on emotions (p < 0.05). The relevant conclusions can provide a reference for optimizing the audio-visual environment of walking space and promoting the sustainable development of the campus. In future research, the effects of audio-visual environments on both emotional and physiological indicators, as well as subjective evaluations, can be explored further.

Noise Exposure and Job Stress – a Structural Equation Model in Textile Industries

Noise exposure is one of the most important physical agents in the workplace which can induce job stress in several ways. The aim of this study was to model the interactions between independent and mediating variables and job stress using structural equation modeling. In this study, Weinstein’s noise sensitivity scale, noise annoyance questionnaire, Health and Safety Executive (HSE) job stress questionnaire and job satisfaction scale were used. To assess worker’s noise exposure, the 8-hours equivalent continuous A-weighted sound pressure level (LAeq;8 h), was measured based on ISO 9612 (2009). To achieve the aims of study, the structural equation model was run using R software 3.4.1 and Cytoscape software 3.6.0. Based on the results, while there was a direct positive correlation of noise exposure on total job stress, there were also indirect positive effects through job satisfaction and noise sensitivity as mediator variables. Using hearing protective devices negatively affected total job stress through a direct pathway and an indirect pathway when job satisfaction was a mediator variable. Regarding the total effect of noise exposure and using hearing protection devices on job stress subscales, it can be concluded that noise exposure and using hearing protection devices had greatest effect on colleagues support and demand, respectively. It can be concluded that noise exposure and lack of hearing protective devices have a significant positive effect on job stress among workers of a textile industry. In addition to the direct effect, this factor can induce job stress through noise sensitivity, job satisfaction and noise annoyance. Therefore, measures which can decrease any of the mentioned factors, also can alleviate job stress.

Smart mobility procedure for road traffic noise dynamic estimation by video analysis

Road Traffic Noise is a major concern in Europe, with more than 20% of people exposed to harmful noise levels. Efficient monitoring and assessment of the sound levels in critical areas are crucial to support decision strategies to control/reduce noise exposure. However, continuous and long-time ranged spatio-temporal measurements require high-cost equipment and maintenance duties. Therefore, this paper aims to develop a cost-efficient smart mobility procedure for the estimation of traffic noise levels based on roadside video images. The developed procedure involves an algorithm that extracts traffic volumes, identifies vehicle classes, estimates each vehicle’s speed from video recordings, and a noise assessment component using dynamic microscopic models. These latter are based on existing Noise Emission Models – NEMs, for the assessment of the source sound power levels, coupled with a sound propagation model able to consider each on-road vehicle speed as input and evaluate the equivalent continuous A-weighted sound pressure levels. The developed approach is characterized by a modular structure that easily allows to replace NEMs and/or incorporate extra variables in the sound propagation model. The procedure is tested on a rural road of a medium-sized city, under different levels of service, and results show that the errors concerning the noise estimations are below 1 dBA, revealing high accuracy.

Sound environment in an urban apartment building during and after the COVID-19 lockdown.

Quiet areas, such as quiet communities, are encouraged to maintain a harmonious and peaceful urban living environment, and the design approach has drawn increasing attention in recent years. Related residential standards define the thresholds of quietness concerning noise pollution problems. However, the variations in height across floors of high-rise buildings and time in sound environments have not been detailed. The city of Shanghai experienced a citywide lockdown to contain the spread of COVID-19 showing the evidence of quietness with marked reductions in anthropogenic noise. Here, we conducted noise monitoring in a 14-story apartment building surrounded and shielded by other buildings in a typical urban community during and after lockdown. The mean value of the equivalent continuous A-weighted sound pressure level (L Aeq ) of all 14 floors after lockdown was higher than that during lockdown, and the differences were 3.6 and 3.1 dB during the daytime and night-time periods, respectively. The L Aeq values at low heights were slightly lower than those at high heights during and after lockdown. The variations due to the different heights were not great. However, the change tendency from the ground to the top floors was similar and correlated during and after lockdown. The difference between the maximum and minimum values of the floors was 3 dB during the daytime period and 4.5 to 5.1 dB during the night-time period. The day equivalent continuous A-weighted sound pressure level (L day ) and night equivalent continuous A-weighted sound pressure level (L night ) at the middle building height increased 4.0 and 1.3 dB, respectively, after lockdown. The L Aeq change tendency during a daily cycle during and after lockdown was similar and highly correlated. The differences in the frequency characteristics of noise level were larger within the 63 to 2,000 Hz range. We suggest that the building represents a typical quiet living condition in high-density habitats in China. Notably, the difference is approximately 3 to 4 dB, and the patterns of variation in height and time are similar between the absence and limited presence of anthropogenic noise. In practice, it would be useful to consider specific floor level or time of day.

A study on the control indices and emission limits of substation noise

Equivalent continuous A-weighted sound pressure level (LAeq) underestimates the influence of low-frequency components of substation noise, so it is necessary to optimise control indices and emission limits of substation noise. To this end, 148 noise samples from 110 kV–1000 kV substations were selected. 280 subjects were randomly recruited for listening tests in which the 11-point numerical scale specified by ISO 15666-2021 was used. The mean noise annoyance (Am) of each noise sample was obtained to establish the LAeq-Am model of substation noise. Meanwhile, the LAeq-LFNR model was established based on the low-frequency noise rating number (LFNR) proposed by Broner. Based on these models, the LFNR corresponding to the limit of LAeq could be determined. The limit of sound pressure level of substation noise was proposed at each 1/1 octave band from 31.5 Hz to 500 Hz and the limit-exceeding ratio for the existing substations noise of China was analyzed. Results showed that Am of 500 kV–1000 kV substation noise was 1.0 higher than that of 110 kV–220 kV substation noise on average when LAeq was 25 dBA–80 dBA. LAeq of the latter were 6.1 dBA higher than that of the former on average when Am was 1–10. It was estimated that utmost 20 % of substations need further to take noise control measures in order to meet the limit suggested by this study in China. Binding with the limit of LAeq, the limit of sound pressure level at each octave band proposed according to equal noise annoyance can better evaluate the influence of substation noise.

Physiological evaluations of low-level impulsive sounds generated by an air conditioner.

Air conditioners are typically installed in buildings and vehicles to control thermal conditions for long periods of time. Air conditioners generate certain types of sounds while functioning, which are among the main noise sources in buildings and vehicles. Most sounds produced by the air conditioner do not change with time, and the sound quality of steady sounds has been investigated. However, air conditioners can generate low-level impulsive sounds. Customers complain of the discomfort caused when these sounds disturb the silence in their living rooms and bedrooms. This study aimed to determine the physical factors that have a significant effect on physiological responses to low-level impulsive sounds produced by air conditioners. We used physiological responses because it is difficult for people to evaluate sounds psychologically when they are sleeping or are not focused on the sounds. The A-weighted equivalent continuous sound pressure level (LAeq) and the factors extracted from the autocorrelation function (ACF) were evaluated as physical factors. Participant responses on electroencephalography (EEG) were evaluated. The correlation between the EEG responses and ACF factors was determined. The LAeq, peak, and delay time to the first maximum peak of the ACF were identified as significant factors for physiological responses to low-level impulsive sounds.

Multiple effects of visual-acoustic-thermal perceptions on the overall comfort of elderly adults in residential outdoor environments

We selected typical residential outdoor spaces and five common sounds (birdsong, dance music, traditional opera, conversation and traffic sound) with three A-weighted equivalent continuous sound pressure level (LAeq) (60, 70 and 80 dBA) as visual-acoustic-thermal conditions. 458 elderly adults completed a subjective questionnaire while environmental parameters (meteorological parameters, illumination intensity (LUX), visible green index (VGI) and LAeq) were simultaneously measured to determine effects of visual-acoustic-thermal perceptions on overall comfort. We found that: 1) When physiological equivalent temperature (PET) was above 43.80 °C, the elderly felt thermally uncomfortable. Older adults perceived traffic sound as acoustic uncomfortable when LAeq was higher than 66.1 dBA. A higher VGI decreased the sensitivity of respondents to LUX. 2) Thermal sensation vote (TSV) and thermal comfort vote (TCV) were susceptible to the acoustic and visual environments. The influence of the visual environment and PET on acoustic sensation vote (ASV) and acoustic comfort vote (ACV) were not significant. We found a significant correlation between PET and sunlight sensation vote (SSV). 3) Acoustic and thermal comfort had a one-vote veto tendency relative to overall comfort, but no absolute veto power. Thermal comfort was the most important factor affecting overall comfort in summer while acoustic comfort was the most important in spring. 4) A binary logistic regression to predict overall comfort of elderly adults had 84.7 % accuracy, indicating a good performance.

Evaluation of Soundscape Variations through the Open Public Spaces in Saharan Cities: A Case of Biskra, Algeria

This study aims initially to evaluate the quality of different soundscapes in the public space of the city of Biskra, in Algeria. A total of 35 participants took part in a laboratory experiment, where 28 sound clips of one-minute duration taken from public spaces in the city were used as stimuli. The A-weighted equivalent continuous sound pressure level (LAeq,1min) was calculated. The participants rated the quality of the soundscape using attribute scales provided in their own native language. The results of the questionnaire on the recorded soundtracks confirm that the immediate environment affects the ambient sound level and the quality of the sound environment, where the sound environments of the areas located near the roads, with a high mechanical flow, are considered the most unpleasant and noisy, with a high A-weighted equivalent continuous sound pressure level (LAeq,1min). The findings of this study indicate that there are statistically significant correlations between pleasantness and loudness, presence of mechanical sounds, presence of non-mechanical sounds, and a sound exposure level. In addition, this study shows that there is a significant positive correlation between pleasantness and the presence of non-mechanical sounds. The results also showed an inverse relationship between the presence of mechanical and non-mechanical sounds, and that the absence of mechanical sounds allows natural and human sounds to be more audible, making the soundscape more pleasant and calm according to the results of the questionnaire. From this study, the duality LAeq,1min and the components of the soundscape are very representative indicators of the quality of the soundscape.

Psychological responses to low-level transient sounds in background sounds generated by an air conditioner

Although air conditioners are installed extensively in buildings to achieve thermal amenities over extended periods, they are considered as one of the primary noise sources in buildings. Air conditioners mostly generate sounds that remain constant over time, and the sound quality of these steady sounds has been evaluated in several studies. However, these appliances occasionally generate low-level transient sounds that disturb the users during sleep or at other times when they require silence. This study aimed to determine how users respond to low-level transient background noises generated by air conditioners and correlate their responses with existing physical factors. Subjective loudness, pitch, and annoyance were appraised using a paired comparison method. The A-weighted equivalent continuous sound pressure level (LAeq) and the factors evaluated using the autocorrelation function (ACF) were utilised to characterise low-level transient noises among several background sounds. Multiple linear regression analyses were performed using the statistical values of LAeq and ACF factors. The results revealed the following significant predictive variables used to assess subjective responses to low-level transient background sounds: the 10th percentile values of the delay time of the first maximum peak, width of the initial decay of the ACF, and the difference between the 10th percentile and 90th percentile values of LAeq and the amplitude of the first maximum peak. This suggests that pitch salience, spectral centroid, and the amount of level change can have significant effects on the user’s psychological response to low-level transient sounds among background sounds.

Sound prediction based on footstep-induced vibrations in concrete building using a convolutional neural network

Heavy-weight impact sounds caused by footsteps are a major factor that affects acoustic comfort in concrete residential buildings. An impact monitoring system that predicts sound based on vibration could be beneficial to alter the behavior of the occupant causing excessive sound, or the stored data can be used by mediators in case of disputes to identify the sound source household and assess the disturbance. This study presents a method for predicting the actual impact sound especially footstep in the rooms of buildings. A convolutional neural network (CNN) was used as the prediction model and the signal from vibration sensors placed in the floors and walls of the room as input data. We experimentally collected a dataset and compared its performance according to the location of the vibration sensors and the resolution of the short-time Fourier transform (STFT) feature, which represents footstep-induced vibrations. The highest accuracy was achieved when the vibration signals of both the wall and floor slab were used simultaneously in the CNN model, with the frequency resolution of the STFT of 10 Hz and the window frame offset of 50 ms. The equivalent continuous A-weighted sound pressure level for 2 s was predicted with 0.99 dB as the mean absolute error, and the value of the coefficient of determination was 0.95. The performance of sound pressure level in the 63 and 500 Hz frequency bands achieved mean absolute error of 1.63–2.22 dB.

Study on Subjective Evaluation of Acoustic Environment in Urban Open Space Based on "Effective Characteristics".

With the continuous expansion of urban scale with dense population and traffic and the gradual improvement of residents’ requirements for environmental quality, the traditional evaluation method relying on acoustic energy is not enough to reflect the feelings of urban crowds about acoustic environment quality. The acoustic environment quality evaluation method based on human subjective perception has gradually become one of the research focuses in the field of environmental noise control. In recent years, various subjective and objective acoustic characteristic parameters have been introduced into the study of acoustic environment assessment in the global literature. However, the extraction of “effective characteristics” from a large number of physical and psychoacoustic characteristics contained in acoustic signals and the creation of a scientific and efficient subjective evaluation model have always been key technical problems in the field of acoustic environment evaluation. Based on subjective human perceptions, the overall acoustic environment quality evaluation of urban open spaces is studied in this paper. Based on the “effective characteristic” parameters and the subjective characteristic proposed in the previous research, including equivalent continuous A-weighted sound pressure level (LA), the difference between median noise and ambient background noise (L50 − L90), Sharpness (Sh), as well as satisfaction (Sat), the multivariable linear regression algorithm is used to further study the intrinsic correlation between the proposed “effective characteristics” and subjective perception. Then, a satisfaction evaluation model of the acoustic environment based on “effective characteristics” is built in this paper. Furthermore, the soundwalk evaluation experiment and the MATLAB numerical simulation experiment are carried out, which verify that the prediction accuracy of the proposed model is more than 92%, the consistency of satisfaction level is more than 88%, as well as the changes in the values of Sh and L50 − L90 have a significant impact on the satisfaction prediction of the proposed model. It shows that the proposed “effective characteristics” more comprehensively describe the quality level of the regional acoustic environment in urban open space compared with a single LA index, and the proposed acoustic environment satisfaction evaluation model based on “effective characteristics” has significant accuracy superiority and regional applicability.

Influencing Factors Identification and Prediction of Noise Annoyance-A Case Study on Substation Noise.

Noise-induced annoyance is one person’s individual adverse reaction to noise. Noise annoyance is an important basis for determining the acceptability of environmental noise exposure and for formulating environmental noise standards. It is influenced by both acoustic and non-acoustic factors. To identify non-acoustic factors significantly influencing noise annoyance, 40 noise samples with a loudness level of 60–90 phon from 500–1000 kV substations were selected in this study. A total of 246 subjects were recruited randomly. Using the assessment scale of noise annoyance specified by ISO 15666-2021, listening tests were conducted. Meanwhile, basic information and noise sensitivity of each subject were obtained through a questionnaire and the Weinstein’s noise sensitivity scale. Based on the five non-acoustic indices which were identified in this study and had a significant influence on noise annoyance, a prediction model of annoyance from substation noise was proposed by a stepwise regression. Results showed that the influence weight of acoustic indices in the model accounted for 80% in which the equivalent continuous A-weighted sound pressure level and the sound pressure level above 1/1 octave band of 125 Hz were 65% and 15%, respectively. The influence weight of non-acoustic indices entering the model was 20% in which age, education level, noise sensitivity, income, and noisy degree in the workplace were 8%, 2%, 4%, 4%, and 2%, respectively. The result of this study can provide a basis for factors identification and prediction of noise annoyance.

Analysis of the Effects and Causes of Driver Horn Use on the Acoustic Environment at Urban Intersections in Taiwan

Car horns were originally installed in vehicles for safety. However, many urban areas in several countries face noise problems related to the use of car and motorbike horns. To propose measures to suppress the use of horns, relationships between horn use and factors including driver awareness and behavior, traffic environment, and the transportation system should be investigated. The present study therefore conducted surveys to grasp the current circumstances of horn use and traffic at urban intersections in Taiwan. The relationship between horn use and the traffic volume of standard-sized vehicles was found. According to an analysis of horn use during traffic signal cycles, in many cases, horns were honked after entering intersections to turn left. In particular, horns were honked when the driver waited more than 4 s for the car in front to start moving after the green light allowing left turns was turned on. An analysis of noise levels at intersections showed that the maximum noise level value (LAmax) could be reduced if vehicle horns were not used. Multiple regression analysis also indicated that LAmax values increased with the frequency of horn use. The equivalent continuous A-weighted sound pressure level (LAeq,10min) did not change with driver horn use, and increased with the traffic volume of motorcycles.

Applying kurtosis-adjusted equivalent continuous A-weighted sound pressure level to evaluate risk of occupational hearing loss associated with non-steady state noise

Applying kurtosis-adjusted equivalent continuous A-weighted sound pressure level to evaluate risk of occupational hearing loss associated with non-steady state noise