Sound Pressure Level Measurements Research Articles

Sustainability Relationship Between Space Configuration, Activity Patterns, and Mosque Acoustics Quality

The Great Mosque of Yogyakarta was built in 1773. This mosque has a traditional architectural style. This study investigates the relationship between the mosque's architectural form, the activities inside it, and its acoustic characteristics. It employed quantitative and qualitative methods, including sound pressure level (SPL) measurement, reverberation time, and architectural and activity observations. Acoustic measurements, architectural observations, and activities are conducted inside and outside the mosque from morning to night for one week. The research finding is a spatial continuity pattern identified as the gradation of SPL value. Consistent continuity of SPL values in accordance with the nature of activities hierarchy. The result of this study is to improve mosque noise control by arranging outdoor and indoor spaces in a sustainable manner.

Noise Annoyance from Tram Traffic in the Urban Environment

Abstract The paper deals with the process of environmental risk assessment from exposure to noise from tram traffic. As part of the monitoring of the acoustic situation, measurements of sound pressure levels A were made and evaluated. The survey confirmed the existence of an acoustic risk in the form of a disturbing wailing sound when a tram vehicle passes through a directional curve with a radius of less than 50m. In addition to causing annoyance, the tonal variation of sound above 65 dB causes frostiness, cardiovascular, psychological and auditory problems, thereby damaging the health of people living and moving around the transport routes.

A novel weight-drop seismic energy source for subsurface characterization

Multichannel Analysis of Surface Waves (MASW) studies for subsurface characterization in Central Ganga Basin of India, where thick cover of alluvium absorbs most of the vibrations generated by a sledgehammer source, give low quality seismic data at large offsets and generally provide imaging depth lesser than 30 m due to low quality of dispersion curves at lower frequencies. Therefore, a novel seismic energy source is designed and developed to produce large amplitude surface waves even at longer offsets and for deeper depths of imaging using dispersion analysis of surface waves. The developed source for seismic data acquisition is low-cost, repeatable, portable, and easy to operate with no environmental impact. Unlike the sledgehammer source where the quality of surface waves generated also depends on the person hitting the metal plate, the seismic data quality from the novel weight-drop source is independent of the operator.The developed source is an impact type where a free-falling mass accelerated due to gravitational pull hits onto a base plate coupled with the earth generating vibrations in the ground. The performance of the source was evaluated in a field trial. A receiver array of 24-channel cabled geophones with 3 m spacing was planted on the ground. Seismic data were acquired using the source at 5 m negative offset inline from the first geophone. Seismic data were also recorded with the sledgehammer as a source for comparison. Five shot gathers for each source were acquired with the same acquisition geometry and source position.Shot gathers were analyzed and compared using trace attributes, 1D and 2D Fourier spectra, signal-to-noise ratio, relative energy, and dispersion images. The study shows that the developed source produces low frequency high amplitude signal and better dispersion image, notably in the lower frequency range, in comparison with the sledgehammer source. Therefore, the developed source is adapted to investigate deeper subsurface velocity structure with dispersion curve from high amplitude surface wave analysis. Moreover, the repeatability study suggests that the repeat shot gathers acquired from the developed source have remarkably high degree of similarity. Therefore, seismic data acquisition with the developed source does not require repeat shots for vertical stacking as often done in case of a hammer source. Sound pressure level measurement indicates that the developed source has no adverse environmental impact on the operator. From the field trial of the developed source, it is convinced that the source is cost-effective, portable, easy to operate and handle and is environmentally friendly.

Sound Pressure Level Measurements with Standard and Low Noise Propellers on a Phantom 4 Pro+

One environmental issue regulated by the FAA is the noise created by aircraft. Federal Aviation Regulation (FAR) Title 14 Part 36 deals specifically with sound pressure levels (SPL) according to aircraft type when the aircraft are in close proximity to the ground. Minimizing aircraft noise helps to maintain positive relationships between the aviation community and the general public. Unmanned aircraft systems (UAS) are a very rapidly growing segment of the aviation industry within the National Airspace System (NAS); however, there is currently no regulation for UAS SPL. The UAS are regulated, as of August 29, 2016, such that they are mandated to be in close proximity to the ground (no higher than 400 ft). As with manned aircraft, UAS produce high levels of SPL, much of which is due to the rotors. The combination of close proximity to the ground, high SPL, and increasing UAS density will most certainly result in a negative public reaction. In order to minimize the audible impact of UAS, the author seeks to minimize the SPL of small UAS propellers/rotors via experimental rotor modifications. These modifications were inspired by the characteristics found on the flight feathers of certain owls. The modifications were evaluated individually and optimized on two-bladed rotors on thrust stands. The most recent phase of the project collected SPL data from a DJI Phantom 4 Pro+ UAS in flight with standard and low noise

Noise and Critical Sound Levels During Non-Invasive Ventilation of a Preterm Infant in the Incubator.

Preterm birth and the subsequent necessary treatment in neonatal intensive care units (NICU) subjects the preterm infant to non-physiological noise exposure with potentially adverse consequences for short- and long-term development. Adjusters to improve the acoustic environment for the preterm infant need to be defined. Sound pressure level measurements during routine procedures in a NICU were performed by ¼" microphones placed inside and outside the incubator. The microphones need to be suitably positioned to measure sound pressure levels that are representative for the sound field inside and outside the incubator. The sound pressure level spectra generated by respiratory support and corresponding monitor alarms were compared. Inside the incubator, higher sound level pressures (in dBA) were generated primarily by the use of the system components of the incubator itself than outside, whereas when the incubator was closed, it had an insulating effect on sounds generated in the NICU. Non-invasive ventilation resulted in an increase in sound pressure levels from 50 to 60 dBA in the neonate's environment, with sound pressure levels increasing particularly in the frequency range above 1 kHz. Preterm infants are exposed to high sound levels, especially in the non-physiological high-frequency range, particularly during non-invasive ventilation. The continuous sound exposure could be further reduced to some extent by an optimized design of the incubator.

Integration and Flight Test of a 7 kW Turboelectric Vertical Take-Off and Landing Unmanned Aircraft

This paper evaluates the performance and practical challenges associated with fabricating and flight testing an unmanned aircraft powered by a turboelectric system based on a 7 kW turbine engine. Emerging hybrid gas-electric aircraft concepts have been the subject of numerous design studies and analytical evaluations; however, there is a critical need to identify and assess practical issues associated with integrating a hybrid turboelectric power system into an aircraft. The purpose of this study, relevant to emerging hybrid-powered aircraft, is to evaluate and retrofit a prototype turboelectric power system to an existing 391 N gross take-off weight unmanned airframe. The representative 7 kW turboelectric system was installed to identify challenges and to formulate data-driven recommendations for general application to urban air mobility. This work addresses performance, power and thermal management, vibration, and acoustic emissions. Results include a weight breakdown with the turboelectric system making up 21% of the total aircraft weight, in-flight voltage and current measurements with maximum loads observed during a dive pull-out, temperature measurements, accelerometer measurements, and far field sound pressure level measurements. Practical recommendations from this study are applicable to power system reliability, electronic component selection, cooling requirements, and peak power behavior, informing the design of future hybrid gas–electric aircraft.

Analysis of the Acoustic Comfort in Hospital: The Case of Maternity Rooms

Hospitals include a variety of different spaces with different requirements and levels of sensitivity to noise but also different activities and equipment that can cause high noise levels. In this article, noise disturbance in hospitals is studied with reference to a case study in a maternity ward. The analysis is carried out by means of sound insulation measurements between bedrooms and between bedroom and corridor. Equivalent sound pressure level measurements were carried out continuously for two days and nights. The number of awakening events is examined for each hour of the two nights. In addition, the results of a questionnaire conducted on more than 100 patients are reported. The results of the study show that the main cause of noise disturbance is activity in the corridors and that this kind of disturbance is usually repeated throughout the night. This is made more critical by the poor acoustic performance of the doors, but also by the habit of keeping doors open or half-open to allow doctors to always control patients. The article proposes some possible solutions to reduce noise intrusion from the corridor to the rooms.

Effects of Forest on Birdsong and Human Acoustic Perception in Urban Parks: A Case Study in Nigeria

The quality of the natural sound environment is important for the well-being of humans and for urban sustainability. Therefore, it is important to study how the soundscape of the natural environment affects humans with respect to the different densities of vegetation, and how this affects the frequency of singing events and the sound pressure levels of common birds that generate natural sounds in a commonly visited urban park in Abuja, Nigeria. This study involves the recording of birdsongs, the measurement of sound pressure levels, and a questionnaire evaluation of sound perception and the degree of acoustic comfort in the park. Acoustic comfort, which affects humans, describes the fundamental feelings of users towards the acoustic environment. The results show that first, there is a significant difference between the frequency of singing events of birds for each category of vegetation density (low, medium, and high density) under cloudy and sunny weather conditions, but there is no significant difference during rainy weather. Secondly, the measured sound pressure levels of the birdsongs are affected by vegetation density. This study shows a significant difference between the sound pressure levels of birdsongs and the vegetation density under cloudy, sunny, and rainy weather conditions. In addition, the frequency of singing events of birds is affected by the sound pressure levels of birdsongs with respect to different vegetation densities under different weather conditions. Thirdly, the results from the respondents (N = 160) in this study indicated that the acoustic perception of the park was described as being pleasant, vibrant, eventful, calming, and not considered to be chaotic or annoying in any sense. It also shows that the human perception of birdsong in the park was moderately to strongly correlated with different densities of vegetation, and that demographics play an important role in how natural sounds are perceived in the environment under different weather conditions.

Evaluation of the Acoustic Environment of Urban Recreational Trails

The acoustic environment state of four recreational trails in Taichung was investigated. First, the basic forms, spatial proportions, characteristics of the trail interfaces, and sound sources of the recreational trail spaces were investigated. Second, sound pressure level measurement and a questionnaire survey were conducted in relation to the four trails. The measurements demonstrated that the sound levels of the four trail spaces are lower than the permissible exposure limit 90 dB(A) recommended by the Occupational Safety and Health Administration. Meanwhile, the results of the factor analysis show that the perception of the acoustic environment of recreational trails has five dimensions: likability, intensity, communication, joyfulness, and richness. Compared with the acoustic environments of other cities, the perception of the acoustic environment of the recreational trails in this city was characterized by more dimensions and a more balanced structure.

Methods for Measuring and Identifying Sounds in the Intensive Care Unit.

BackgroundDespite many studies in the field examining excessive noise in the intensive care unit, this issue remains an ongoing problem. A limiting factor in the progress of the field is the inability to draw conclusions across studies due to the different and poorly reported approaches used. Therefore, the first goal is to present a method for the general measurement of sound pressure levels and sound sources, with precise details and reasoning, such that future studies can use these procedures as a guideline. The two procedures used in the general method will outline how to record sound pressure levels and sound sources, using sound level meters and observers, respectively. The second goal is to present the data collected using the applied method to show the feasibility of the general method and provide results for future reference.MethodsThe general method proposes the use of two different procedures for measuring sound pressure levels and sound sources in the intensive care unit. The applied method uses the general method to collect data recorded over 24-h, examining two beds in a four-bed room, via four sound level meters and four observers each working one at a time.ResultsThe interrater reliability of the different categories was found to have an estimate of >0.75 representing good and excellent estimates, for 19 and 16 of the 24 categories, for the two beds examined. The equivalent sound pressure levels (LAeq) for the day, evening, and night shift, as an average of the sound level meters in the patient room, were 54.12, 53.37, and 49.05 dBA. In the 24-h measurement period, talking and human generated sounds occurred for a total of 495 (39.29% of the time) and 470 min (37.30% of the time), at the two beds of interest, respectively.ConclusionA general method was described detailing two independent procedures for measuring sound pressure levels and sound sources in the ICU. In a continuous data recording over 24 h, the feasibility of the proposed general method was confirmed. Moreover, good and excellent interrater reliability was achieved in most categories, making them suitable for future studies.

Sounds in the urban square: qualitative influences on users' lives

Noise pollution is a worldwide public health problem that directly influences the population's quality of life. The study of the soundscape in public spaces seeks to identify the perceptions of users and how it influences the experience in a given place. Thus, the aim of this study is to characterize the soundscape of Parque Halfeld square in Juiz de Fora, indicating how visitors assess the acoustic quality of this space. From on-site sound pressure levels measurements in the square and application of a questionnaire about the sound perception based on the Swedish SSQP (Swedish Soundscape-Quality Protocol), the results address the noise levels and the relationships between the users’ characteristics and the types of sounds perceived, as well as the related feelings. This study indicates that age, reason, and frequency of visits are some of the factors that most influence the perception of the soundscape and central areas of the square, a region with lower levels of sound pressure, are more pleasant in acoustic aspects. The questionnaire applied is also a contribution of this study to future research in the country. Given the pandemic scenario and the greater use of open spaces, this study can contribute to the planning of squares based on people's perception of the soundscape.

3D noise modeling of an urban environment: Simulated and measured noise characteristics of the University of the District of Columbia campus

In this work, a 3-D numerical method is employed to predict the noise propagation within the University of the District of Columbia (UDC). UDC is located within an urban environment in Washington, DC. Sound pressure level measurements of various noise sources including traffic noise are obtained. Of particular interest is the method’s ability to accurately simulate the urban space. Accuracy is evaluated comparatively between simulated and measured results of acoustic parameters in the mid- to high-frequency regimes. Specifically, reverberation time, energy decay time, and sound pressure level. The results and limitations of the particle-tracing method for predicting sound propagation in urban environments are discussed.

Conforto Acústico: um caminho possível para a Saúde dos Profissionais a exercer em escolas

Introduction Tree planting reduces noise pollution and consequently improve the quality of life, however, in Brazil there is little research on this topic, mainly related to the quantification and classification of vegetation in the health of workers. It is understood that the correct planning of afforestation at school is essential, as it makes the place attractive, with functional and aesthetic quality, adequate landscaping and favorable acoustic conditions. Thus, acoustic comfort can favor the teaching process, as it minimizes the educator's vocal effort. Given these considerations, this work exposes the need to obtain acoustic comfort in a school located in the central area of a city in the interior of the State of São Paulo, Brazil. Objective To measure the sound pressure levels in three environments in the school yard of a central school in a city in the interior of the state of São Paulo, Brazil; verify the existence of arboreal masses in the school yard and near the school under study and to find out if the tree mass contributes to the acoustic comfort of the school yard under study. Methodology The measurement of sound pressure levels was carried out in the school yard in October 2019, at 9:30 am within the three established points. The measurement followed ANSI S12.60 recommendations, using Instrutherm DEC-5050 sound meter equipment and compared with NBR 10.151 and NBR 10.152 Standards. At the three determined points, 30 measurements were performed at each point, spaced 10 seconds each, at each point, according to the manual for measurement and calculation of acoustic conditions. Measurements were taken at 1.2 m above ground and 1.5 m from walls. Results The school does not comply with NBR 10152, with sound pressure levels up to 88.9 dB (A), with regard to acoustic comfort, compromising the occupational health and quality of life of educators and the learning process of students. The lack of arboreal mass can significantly contribute to noise pollution and compensatory considerations of mitigating proposals in future studies to solve the acoustic problems that affect the lives of educators and students. Conclusion Environmental noise in the school yard is above acceptable limits, impacting acoustic quality and comfort, which can contribute to a process of auditory effort, which impairs the teaching process and quality of life, interfering with the health of educators and students. Therefore, it is essential to search for solutions to improve the acoustic quality of the environment, with a favorable acoustic landscape. The arboreal mass shows promise for acoustic comfort in the school environment, providing better health conditions for educators and students. Therefore, it is suggested as future studies: Propose the type of material for the architectural space so that the place has less noise; improve the positioning of the afforestation present at the site and Implement afforestation project as needed by the site. Keywords: Acoustic comfort, Trees, Schoolyard, School Health Program, Occupational Health.

The impact of the technical requirements of the renovation grant on the ventilation and indoor air quality in apartment buildings

In this study, the impact of ventilation requirements set in the conditions of a renovation grant was analysed with field measurements. Effects of renovation measures applied in two grant periods on the air change rate (ACR) and indoor air quality (IAQ) of apartments were examined. CO2 levels and airflow rates were measured in 21 buildings during the first renovation grant period and in 15 buildings in the second grant period. During the first grant period, the average ACR studied apartments was as low as 0.17 h−1, and in the second grant period ACR had improved to 0.57 h−1, complying with requirements. Room-based ventilation requirements as well as heat recovery and preheating of intake air, mandatory airflow rate and sound pressure level measurement protocols, and third party inspection of design documentation assured adequate ventilation and IAQ in the second grant period. Centralized mechanical supply and exhaust ventilation with heat recovery resulted in best performance but an alternative system with exhaust heat pump and ventilation radiators may also be recommended. We concluded, that the installation of proper ventilation system is a key issue in renovation. The results of the study are a valuable input in designing technical conditions of the renovation grant.

Experimental characterization of a household heat pump tumble dryer noise

In this paper, an experimental approach for acoustic characterization of a household heat pump tumble dryer is developed. The main noise sources including BLDC motor, centrifugal fan, drain pump, and ventilation duct were identified using an acoustic camera survey based on beamforming, sound pressure level, directivity, and laser Doppler vibrometer vibration velocity measurements. In addition, noise reduction measures were taken, and sound power level and directivity measurements were used to evaluate the significance of the identified sources on the total noise emission. As a result, the A-weighted sound power level was reduced from 64.8 to 60.4 dB and the directivity pattern was improved. The proposed experimental approach for noise identification and the validation approach can be applied to other complex household appliances of similar size.

A comparison of measurement of sound pressure level in timber structures

A comparison of measurement of sound pressure level in timber structures

Rancang Bangun Alat pendeteksi Tingkat Tekanan Bunyi Terhadap Respon Membran Timpani Berbasis Serat Optik

It has been designed a sound pressure level detection for response of tympanic membrane based on optical fiber with extrinsic method. The fiber optic sensor is used to measure the sound pressure level by utilizing the output voltage change. The sound level pressure values obtained are displayed on OLED display. Testing tools with sound level meter comparison tool to test sound pressure level in poly ENT patients. The test results show that at sound pressure level measurement with frequency 200 Hz to 300 Hz, the average accuracy is 93.42% for right ear, at the same time for left ear the average accuracy is 94.58%. The test of compliance measurement the average accuracy is 77.97% for the right ear, at the same time for the left ear the average accuracy is 70.74%. The testing of the appliance to patient in Andalas University hospital poly ENT were detect the values of sound pressure level 60 dB to 65 dB.

Rancang Bangun Alat pendeteksi Tingkat Tekanan Bunyi Terhadap Respon Membran Timpani Berbasis Serat Optik

It has been designed a sound pressure level detection for response of tympanic membrane based on optical fiber with extrinsic method. The fiber optic sensor is used to measure the sound pressure level by utilizing the output voltage change. The sound level pressure values obtained are displayed on OLED display. Testing tools with sound level meter comparison tool to test sound pressure level in poly ENT patients. The test results show that at sound pressure level measurement with frequency 200 Hz to 300 Hz, the average accuracy is 93.42% for right ear, at the same time for left ear the average accuracy is 94.58%. The test of compliance measurement the average accuracy is 77.97% for the right ear, at the same time for the left ear the average accuracy is 70.74%. The testing of the appliance to patient in Andalas University hospital poly ENT were detect the values of sound pressure level 60 dB to 65 dB.Â

Distortion measurements of sound pressure level generated by a pistonphone

A supplementary interlaboratory comparison on pistonphone calibration was performed between 2018 and 2020 under the auspices of the Inter-American Metrology System. Seven national metrology institutes took part in this comparison. One pistonphone was circulated among the participants for measurement of the generated sound pressure level, frequency, total distortion + noise and total harmonic distortion. This paper presents the results of distortion measurements and analyzes them. From the stability check, notable variances with respect to reported measurement uncertainty were observed. From reported results, a large difference between the estimated uncertainties by the participants was noted. Convergence between results was found when measurements were performed using one-inch microphone while some divergence between results was found when measurements were performed using half-inch microphone. In addition, these results (using one-inch and half-inch microphones), even when obtained by the same institute, sometimes were different. Reasons for these findings are discussed and suggestions for future comparisons are presented.

Landscape depressions can create silent zones in noise polluted parks

Excessive road traffic noise exposure in (sub)urban parks hinders its restorative function and will negatively impact the number of visitors. Especially in such green environments, noise abatements by natural means, well integrated in the landscape, are the most desired solutions. Although dense vegetation bordering the park or raised berms could come first in mind, local landscape depressions are typically underused. In this work, a case-study of a small suburban park, squeezed in between two major arterial roads, is analyzed. The spatially dependent road traffic noise exposure in the park is assessed in detail by mobile sound pressure level measurements. Local reductions of up to 6-7 dBA are found at landscape depressions of only a few meters deep. It can therefore be concluded that this is an efficient measure and should be added to the environmental noise control toolbox for noise polluted parks.