IoT-based sound-level control for audio amplifiers: mosques as a case study

<p><span>When using audio-amplifiers in the open, uneven distribution of sound makes people unpleasant because it is loud or unheared. This unfortunate situation arises because audio-amplifiers volumes are set according to the guess of sound technicians. Mosques, as an example, are distributed inside wide areas and fire Azan five times a day. Due to the relatively long distances between them, speed and direction of the wind impose setting sound levels prior to each Azan such that all the area is covered and the overlap is minimized. In this paper, we propose a system based on internet of things (IoT) model to control the sound level of each mosque in the community. An IoT device (one in a mosque) sets the level of sound fired by the audio-amplifier. To do that, a synchronized series of tones is fired from each node. Once a node hears these tones, the process of sound level control starts to indicate the distances to heared nodes. As the approximate distances between nodes are known, each node can calculate its suitable sound level. Results showed that the proposed system is effective in setting sound levels for mosques audio amplifiers.</span></p>

Wind Farm Noise Management Based on Determinants of Annoyance

Wind energy in Europe is aimed to grow at a steady, high pace. Wind turbine noise is an important issue for residents. Environmental noise management aims to reduce the exposure of the population, usually based on acoustics and restricted to a limited number of sources (such as transportation or industry) and sound descriptors (such as Lden). Individual perceptions are taken into account only at an aggregate, statistical level (such as percentage of exposed, annoyed or sleep-disturbed persons in the population). Individual perceptions and reactions to sound vary in intensity and over different dimensions (such as pleasure/fear or distraction). Sound level is in fact a weak predictor of the perceived health effects of sound. The positive or negative perception of the sound (source) is a better predictor of its effects. This article aims to show how the two perspectives (based on acoustics and on perception) can lead to a combined approach in the management of environmental sound. In this approach the reduction of annoyance, not primarily of level, is the main aim. An important aspect in this approach is what a sound means to people: does it lead to anxiety or worry, is it appropriate? The available knowledge will be applied to wind farm management: planning as well as operation.

Pengaruh Intensitas Kebisingan Terhadap Gangguan Pendengaran, Gangguan Psikologis dan Gangguan Komunikasi pada Pekerja di PT. Maruki International Indonesia Makassar Tahun 2020

Kebisingan menimbulkan beberapa dampak pada kesehatan. Selain berdampak pada gangguan pendengaran. intensitas bising yang tinggi juga dapat mengakibatkan hilangnnya konsentrasi, hilangnya keseimbangan dan disorientasi, kelelahan, gangguan komunikasi, gangguan tidur, gangguan pelakasaan tugas, gangguan faal tubuh, serta adanya efek visceral, seperti perubahaan frekuensi jantung atau peningkatan denyut nadi, perubahaan tekanan darah dan tingkat pengeluaran keringat. Penelitian ini bertujuan untuk mengetahui pengaruh intensitas kebisingan terhadap gangguan pendengaran, gangguan psikologis dan gangguan komunikasi pada pekerja di PT. Maruki International Indonesia Makassar tahun 2020. Jenis penelitian yang digunakan adalah pendekatan kuantitatif dengan rancangan cross sectional study, dengan sampel 32 pekerja secara sampling jenuh dari pekerja Factory 1 dan 2 di PT. Maruki International Indonesia Makassar. Teknik pengambilan data dilakukan dengan menggunakan kuesioner, alat sound level meter untuk pengukuran intensitas kebisingan. Selanjutnya data dianalisis menggunakan uji chi-square pada tingkat kepercayaan 95% (α=0.05). Hasil penelitian yang diperoleh adalah ada pengaruh intensitas kebisingan terhadap gangguan pendengaran dengan nilai p = 0.022, ada pengaruh intensitas kebisingan terhadap gangguan psikologis dengan nilai p = 0.017, dan tidak ada pengaruh intensitas kebisingan terhadap gangguan komunikasi dengan nilai p = 0.474. Disarankan kepada pimpinan untuk mengutamakan kesehatan dan keselamatan kerja dengan lebih meningkatkan upaya pengendalian kebisingan yang sudah dilakukan dan menambah preventif lainnya seperti pelatihan mengenai penggunaan APT (Alat Pelindung Telinga) pada saat bekerja di lingkungan yang bising.

Influence of road traffic noise peaks on reading task performance and disturbance in a laboratory context

The influence of fluctuating road traffic noise on perceived disturbance during a reading task as well as on performance, inside a living room with closed windows, is presented in this paper. Sixteen 2-min sound sequences were created combining two variables: the number of events (four levels varying from one to four car pass-bys) and the peak emergence above the background noise (four levels with a 5 dB(A) step) keeping limited variations of LAmax, 1s. The noise impact was evaluated through a reading task of texts synchronized with the sound sequences, for participants classified into fast or slow readers, and sensitive or non-sensitive to noise. The comprehension rate of the texts decreases as the background sound level increases. The reading speed decreases during the rising front of a peak, and goes back to its former regular reading speed during the descending front of the peak. This slowdown during the rising front reaches 14% for slow readers. The declared disturbance is higher for slow readers compared to fast readers, and higher for noise sensitive persons compared to non-sensitive persons. The influence of the acoustic indicators on the reading disturbance is very small compared to the influence of personal factors. There is even no influence of the number of events on this disturbance.

Noise Pollution Monitoring at Some Indoor Environments in Basrah City, Iraq

Noise is an unavoidable stressor nowadays; it adversely affects human health and the ability to perform mental and complex tasks. Eight selected points representing home environment were sampled in urban zones, the indoor and outdoor noise levels in these residential areas were evaluated during the summer and winter seasons. Also, nine points in educational institute represented by the College of Science through its lecture halls, laboratories and corridors, to compare them with WHO limits of sound pressure levels, to assess the level of noise experienced by people in indoor closed environments. The current study results showed higher sound levels than required inside homes and educational places. For homes, the highest sound level was 73.9 dB during summer in the living room and the lowest was 42.1 in winter in the bedroom, while the highest sound level in the educational environment was 72.37 dB in summer and the lowest was 61.75 dB in winter. Exposure of individuals to high levels of noise in educational institutions and in their homes means longer hours of exposure to noise pollution, which will negatively affect their health. Thus there is a serious need nowadays to adopt suitable control to reduce noise pollution at indoor points.

Measuring Air Quality Over Denpasar City Indonesia in 2021

The imbalance number of rapid vehicles with transportation facilities has become the problem. In Denpasar, Indonesia, the congestion during peak hours happens so often. Based on the department of transportation in Denpasar, Indonesia, the number of vehicle ownership in Bali is 4.1 million in condition with a ratio of one resident to one vehicle with the current population of Bali Province approximately 4.2 million. Our study aim to measure the air chemical parameters of CO, O3, SO2, NO2 and the physical parameters of the noise level. The research population is the atmosphere environment in the Denpasar City area. The research sample points were taken in the city center and the outskirts of Denpasar, with a total of 27 sample points. We employed impinge to get the airborne chemical gases and it is all analyzed with a spectrophotometer. We used a sound level meter to measure the ambient noise level. The data analysis was performed with free sample t test. The average ambient air chemistry obtained CO 517.34 µgr/Nm3, O3 0.17 µgr/Nm3, SO2 61.46 µgr/Nm3 and NO2 2.51 µgr/Nm3 and an average noise level 67.66 dBA. The number has found below the requirements Environmental Quality Standards and Environmental Damage Standard Criteria by Bali Governor. There is a difference in the mean parameters of CO, SO2, NO2 and ambient noise level in the downtown area. The average CO is 757.15 µgr/Nm3, SO2 67.60 µgr/Nm3, NO2 3.77 µgr/Nm3 and the noise level is 68.53 dBA with Denpasar outskirts mean CO 217.57 µgr/Nm3, SO2 53.79 µgr/Nm3, NO2 0.95 µgr/Nm3 and noise level 66.57 dBA. There is no difference in the average ambient O3 in the city center area with an average of 0.22 µgr/Nm3 with the outskirts of Denpasar an average of 0.11 µgr/Nm3.

TRAFFIC DENSITY DUE TO MOTORCYCLE NOISE DURING THE PANDEMIC COVID-19

<p>The density of motorized vehicles, especially motorcycles on the highway, is getting higher. However, in line with the 2020 Covid-19 pandemic, it has an impact on the decrease in the number of motorized vehicles on the highway. The density of motorcycles has a significant effect on noise, from all analysis calculations, the largest equation is obtained on the fourth day of the study, the second point (Sound Level Meter 2), with a contribution of 32.42%. Obtained the calculation below, y = 63.36 + 0.002x1. This equation means that if there is no decrease in motorcycle density, the noise level in SLM2 is 63.36 dBA. If there is a motorcycle density also has a significant effect on noise. The second largest equation was obtained on the third day of research at the third point (Sound Level Meter 3) with a contribution of 36.21% based on the equation calculation below, y = 60.24 + 0.001x1. The meaning of the above equation is that if there is an increase in the density of the motorcycle, the noise in the SLM3 is 60.24 dBA. The Covid-19 pandemic that has hit the world, Indonesia is also getting its effects, especially the very large Bogor district. The rapid spread of Covid-19 has changed the pattern of life for the people of Bogor, especially students who initially go to school every morning, now go to school and study online.</p>

CLASSIFICATION AND MODELLING OF SOUND EMISSION SIGNALS IN SELECTED TRIBOSYSTEMS

The paper presents an analysis of the sound level recorded during dry sliding friction conditions. Balls with a diameter of 6 mm placed on pins were made of 100Cr6 steel, silicon carbide (SiC), and corundum (Al2O3), while rotating discs with a height of 6 mm and a diameter of 42 mm were made of 100Cr6 steel. Each pin and disc system was tested for two values of the relative humidity of the air (50 ± 5% and 90 ± 5%). Models of the A-sound level were developed using regression trees and random forest. The paper presents an analysis of the accuracy of the models obtained. Classifications of the six tests performed on the basis of sound level descriptors were also carried out.