Hygienic Characteristics of the Acoustic Environment in the Mi-8 Helicopter Cabin

2021 ◽  
pp. 54-61
Author(s):  
VV Kharitonov
Keyword(s):  
Working Conditions ◽  
Sound Pressure ◽  
Bone Conduction ◽  
Central Compartment ◽  
Sound Level ◽  
Exposure Limits ◽  
Acoustic Environment ◽  
Operating Modes ◽  
Technical Requirements ◽  
Sound Pressure Levels

Introduction: The Mi-8 helicopter generates high-intensity broadband noises by its turboshaft engines whereas a comprehensive hygienic assessment of the acoustic environment in the helicopter cabin has not been conducted. The purpose of the study was to assess the acoustic environment in the Mi-8 helicopter cabin. Materials and methods: Acoustic measurements were carried out on the ground, inside the central cabin of the Mi-8 helicopter in three operating modes of the turboshaft engines: at startup, in the idle mode, and during cruise flight in the “right correction” mode. Measuring microphones were placed during the recording of the signal on a stand at the level of the human ear at six points located next to the reclining seats in the cabin. Acoustic indicators were measured using an SVAN-945A digital sound level meter and a GRAS 40AZ microphone. The collected data were processed in accordance with the requirements of sanitary and epidemiological rules, sanitary standards, and general tactical and technical requirements of the Air Force. Results: Values of regulated noise indicators at the seats of the Mi-8 helicopter crew, sound pressure levels of the most significant tonal frequencies in its central compartment were measured. To establish the presence of tonal noise, a one-third octave analysis of the recorded acoustic signals was carried out. In the central compartment of the helicopter, the values of the regulated infrasound indices and the general sound pressure level were measured in the entire regulated frequency range. Discussion: It was found that the sound pressure levels in almost all sound octaves and the equivalent sound level in all operating modes of the helicopter engines exceed the permissible exposure limits while in the infrasound region they are within the normal range (except for the frequency of 16 Hz). Thus, the class of working conditions by noise corresponds to hazard class 3.3, and by infrasound – to class 2. According to the sanitary regulations, helicopter crews should use noise suppressors to protect themselves from high noise exposures through air and bone conduction. Conclusion: The existing risks of developing a noise and infrasound-induced diseases necessitate constant monitoring of working conditions and health of the crews of Mi-8 helicopters.

scholarly journals Investigation of Noise Pollution Distribution in Different Parts of Yazd Textile Factories

2021 ◽  
Author(s):  
Mohammad Javad Zare Sakhvidi ◽  
Hamideh Bidel ◽  
Ahmad Ali Kheirandish
Keyword(s):  
Occupational Exposure ◽  
Sound Pressure Level ◽  
Textile Industry ◽  
Sound Pressure ◽  
Noise Pollution ◽  
Sound Level ◽  
Pressure Level ◽  
Cross Sectional ◽  
Sound Pressure Levels ◽  
Different Parts

 Background: Chronic occupational exposure to noise is an unavoidable reality in the country's textile industry and even other countries. The aim of this study was to compare the sound pressure level in different parts of the textile industry in Yazd and in different parts of the textile industry. Methods: This cross-sectional study was performed on 930 textile workers in Yazd. A questionnaire was used to obtain demographic information and how to use protective equipment. Then, to obtain the sound pressure level of each unit and device and to use the measurement principles, a calibrated sound level meter was used. Then the results were analyzed using SPSS Ver.29 software. Results: The participants in this study were 714 males and 216 females with a mean age of 35.27 and 33.63 years, respectively. Seven hundred fifty-six participants (81.29%) were exposed to sound pressure levels higher than 85 dB. Among the participants, only 18.39% of the people used a protective phone permanently. Except for factory E, with an average sound pressure level of 77.78 dB, the rest of the factories had an average sound pressure level higher than the occupational exposure limit. The sound measurement results of different devices show that the sound pressure levels above 90 dB are related to the parts of Dolatab, Ring, Kinetting (knitting), Chanel, Autoconer, Dolakni, Open End, MultiLakni, Tabandegi, Texture, and Poy. Conclusion: Based on the results of the present study, noise above 90 dB is considered as one of the main risk factors in most parts of the textile industry (spinning and weaving), which in the absence of engineering, managerial or individual controls on it causes hearing loss in becoming employees of this industry

Assessment of Environmental Noise and Air Quality in Critical Areas at UiTM Engineering Complex

2013 ◽  
Vol 471 ◽  
pp. 125-129
Author(s):  
N.V. David ◽  
K. Ismail
Keyword(s):  
Air Quality ◽  
Sound Pressure ◽  
Quality Measurement ◽  
Environmental Noise ◽  
Sound Level ◽  
Public Parks ◽  
Noise Sources ◽  
Critical Areas ◽  
Sound Levels ◽  
Sound Pressure Levels

Excessive environmental noise and poor air quality can be adverse to human health, living comfort and the environment itself. Measurement of sound pressure levels and air quality in critical areas including libraries, campus areas, public parks and hospitals thus becomes necessary to monitor and mitigate existing noise levels. In a university environment, student activities will be less disrupted if the locations of the activities are sufficiently away from noise sources. The present study is intended to measure sound levels and air quality around the Engineering Complex, Universiti Teknologi Mara, Shah Alam. The measured data is compared with to acceptable sound pressure levels and air quality index specified by the Department of Environment (DOE), Malaysia. Sound pressure levels are measured using the Castle Sound Level Meter Type 6224 and air quality measurement was done by using the BW Gas Alert MicroClip XT device. Both measurements were conducted at five selected stations around the Engineering Complex for three times each weekday for five weeks. Results obtained indicated that sound levels at some locations and time zones are above the thresholds recommended by the DOE. The air quality is acceptable in most locations except the vicinity of a bus stop. With the growing number of students in the university and other factors like construction and redevelopment of existing roads, a continuously increasing noise situations and air pollution proportional to the traffic flow is inevitable.

R-weighting provides better estimation for rat hearing sensitivity

2000 ◽  
Vol 34 (2) ◽  
pp. 136-144 ◽  
Author(s):  
E. Böjrk ◽  
T. Nevalainen ◽  
M. Hakumäki ◽  
H.-M. Voipio
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Studies ◽  
Response Curves ◽  
Acoustic Environment ◽  
High Frequencies ◽  
Hearing Sensitivity ◽  
Sound Levels

Since sounds may induce physiological and behavioural changes in animals, it is necessary to assess and define the acoustic environment in laboratory animal facilities. Sound studies usually express sound levels as unweighted linear sound pressure levels. However, because a linear scale does not take account of hearing sensitivity-which may differ widely both between and within species at various frequencies-the results may be spurious. In this study a novel sound pressure level weighting for rats, R-weighting, was calculated according to a rat's hearing sensitivity. The sound level of a white noise signal was assessed using R-weighting, with H-weighting tailored for humans, A-weighting and linear sound pressure level combined with the response curves of two different loudspeakers. The sound signal resulted in different sound levels depending on the weighting and the type of loudspeaker. With a tweeter speaker reproducing sounds at high frequencies audible to a rat, R- and A-weightings gave similar results, but the H-weighted sound levels were lower. With a middle-range loudspeaker, unable to reproduce high frequencies, R-weighted sound showed the lowest sound levels. In conclusion, without a correct weighting system and proper equipment, the final sound level of an exposure stimulus can differ by several decibels from that intended. To achieve reliable and comparable results, standardization of sound experiments and assessment of the environment in animal facilities is a necessity. Hence, the use of appropriate species-specific sound pressure level weighting is essential. R-weighting for rats in sound studies is recommended.

scholarly journals The Effect of Music Tempo and Volume on Acoustic Perceptions under the Noise Environment

2021 ◽  
Vol 13 (7) ◽  
pp. 4055
Author(s):  
Ping Liang ◽  
Hongyu Guan ◽  
Yuezhen Wang ◽  
Han Chen ◽  
Pengfei Song ◽  
...  
Keyword(s):  
Sound Pressure ◽  
Orthogonal Experiment ◽  
Subjective Evaluation ◽  
Traffic Noise ◽  
Experimental Conditions ◽  
Acoustic Environment ◽  
Noise Environment ◽  
Sound Pressure Levels ◽  
Acoustic Comfort ◽  
Human Perceptions

This study aimed to investigate the distracting or masking effects of music tempo and volume, based on subjective evaluation under noise conditions. Two experiments were conducted with 32 participants. In the first one, the experimental conditions were set as follow: (1) the sound pressure levels of music are 45 dB, 60 dB, and 75 dB; (2) music tempos are 70 beats per minute (BPM), 110 BPM, and 150 BPM; (3) sound pressure levels of noise are 45 dB, 60 dB, and 75 dB; and (4) the noise types are talkers’ babble, traffic noise, and construction noise. All conditions on human acoustic perception were analyzed by orthogonal experiment. Based on part one, the second experiment was conducted. Sound pressure levels (50 dB, 60 dB, and 70 dB) of noise and sound pressure levels (50 dB, 60 dB, and 70 dB) of music and music tempo (70 BPM, 110 BPM, and 150 BPM) were assessed by subjective evaluation. The results showed although different types of noise had different effects on human perceptions, noise types had a small effect on acoustic comfort considering the superimposed music. Music can improve the acoustic environment. The sound pressure levels had significant effects on acoustic sensation. The tempo of the music affected the acoustic sensation insignificantly. Sound pressure levels of noise, music tempo, and sound pressure levels of music significantly affect acoustic comfort. The best acoustic environment in this study utilized superimposed 70 BPM, 60 dB music in a 50 dB noise environment. These results suggest that music can enable new strategies to improve indoor environmental satisfaction. Based on the findings, the effect of music on acoustic perceptions under the noise environment should be taken into account when aiming to enhance comfort in noisy environments.

scholarly journals Sound comparison of seven TMS coils at matched stimulation strength

2019 ◽  
Author(s):  
Lari M. Koponen ◽  
Stefan M. Goetz ◽  
Debara L. Tucci ◽  
Angel V. Peterchev
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Neural Stimulation ◽  
Hearing Protection ◽  
List Type ◽  
Exposure Limits ◽  
High Bandwidth ◽  
The Subject

AbstractBackgroundAccurate data on the sound emitted by transcranial magnetic stimulation (TMS) coils is lacking.MethodsWe recorded the sound waveforms of seven coils with high bandwidth. We estimated the neural stimulation strength by measuring the induced electric field and applying a strength–duration model to account for different waveforms.ResultsAcross coils, at maximum stimulator output and 25 cm distance, the sound pressure level (SPL) was 98–125 dB(Z) per pulse and 75–97 dB(A) for a 15 Hz pulse train. At 5 cm distance, these values were estimated to increase to 112–139 dB(Z) and 89–111 dB(A), respectively.ConclusionsThe coils’ sound was below, but near, relevant exposure limits for operators and may exceed some limits for the subject. Exposure standards may inadequately capture some risks to hearing. For persons near operating TMS coils we recommend hearing protection, and we consider it essential for the TMS subject.HighlightsCoil click varies by over 20 dB(Z) between TMS coils at matched stimulation strength.Close to TMS coil, sound pressure level may reach nearly 140 dB(Z).For rTMS, the continuous sound level can exceed 110 dB(A).Hearing protection is recommended during TMS, especially for the subject.

Music to Our Ears: Are Dancers at Risk for High Sound Level Exposure?

2020 ◽  
Vol 35 (4) ◽  
pp. 227-232
Author(s):  
Haley Busenbarrick ◽  
Kathleen L. Davenport
Keyword(s):  
Hearing Loss ◽  
Performing Arts ◽  
Sound Pressure ◽  
Sound Level ◽  
Sound Recording ◽  
Exposure Limits ◽  
Moderate Risk ◽  
Sound Exposure ◽  
Daily Dose ◽  
High Sound

Enduring exposure to high sound pressure levels (SPLs) can lead to noise-induced hearing loss (NIHL). In the performing arts population, NIHL has been studied primarily in the context of sound exposure experienced by musicians and less so by dancers. This research aimed to identify sound exposure that dancers may experience in some dance classes. Decibel levels were recorded in 12 dance classes (6 ballet, 4 modern, and 1 soft and 1 hard shoe Irish dance) at 8 different studios using the NIOSH SLM app on an iOS smartphone with external microphone. A minimum of five recordings of each class was measured, each collected on a different day, yielding a total of 114 measurements. Results showed that 20.2% of all recordings exceeded the recommended NIOSH sound exposure limits of both 100% projected daily dose and 85 LAeq. Analysis between styles of dance demonstrated significantly lower LAeq (p≤0.05) in soft shoe Irish dance compared to ballet (p=0.023), modern (p=0.035), and Irish hard shoe dance (p=0.009). Irish soft shoe dance demonstrated minimal to no risk of high sound exposure. Conversely, 53.25% of ballet, 90.9% of Irish hard shoe dance, and 68.24% of modern recordings exhibited minimal to moderate risk of high sound exposure. Furthermore, we found wide ranges of projected daily noise doses within classes taught by the same teacher. It is recommended that multiple recordings of dance environments be obtained, as a single sound recording may not accurately represent potential exposure. These findings indicate that dancers of Irish hard shoe, modern, and ballet may benefit from noise intervention such as audiometric testing, noise controls, and hearing protection.

scholarly journals Evaluation of noise levels in areas and departments of the upper Technological Institute of Guasave

2019 ◽  
pp. 1-5
Author(s):  
Grace Erandy Báez-Hernández ◽  
Viridiana Humarán-Sarmiento ◽  
Claudia Rivera-Rubio ◽  
Brenda Guadalupe Delgado-Jiménez
Keyword(s):  
Working Conditions ◽  
Education Institution ◽  
Sound Level ◽  
Protective Equipment ◽  
Noise Levels ◽  
Exposure Limits ◽  
Permissible Exposure Limits ◽  
Present Experimentation ◽  
Level Meter ◽  
Medical Examinations

The present experimentation is the evaluation of noise levels in laboratories, classrooms and departments of a Higher Education Institution. Its objective is to identify and evaluate the working conditions to which workers and students are exposed when performing tasks. The study was conducted based on the official Mexican Standard NOM 011-STPS-2001 "Conditions of safety and hygiene in workplaces where noise is generated". Using a TES 1353S sound level meter for 4 weeks, evaluating 16 zones, in 2 periods. As a result, it was obtained that 6 of the 16 zones evaluated exceed the maximum permissible exposure limits. And recording discomfort and lack of concentration in the activities to be carried out on workers and students. As a recommendation, the implementation of periodic medical examinations and personal protective equipment for the personnel, in addition to the evaluation of noise levels in the preventive maintenance of the institution.to make the activities more comprehensive.

Measurement and Analysis of the Structural Noise of Urban Bridges

2014 ◽  
Vol 548-549 ◽  
pp. 1623-1626
Author(s):  
Tao Jin ◽  
Qi Huang ◽  
Yong Ding ◽  
Li Feng Zhu
Keyword(s):  
Sound Pressure ◽  
Low Frequency ◽  
Measured Data ◽  
Sound Level ◽  
Frequency Noise ◽  
Acoustic Environment ◽  
The Road ◽  
Sound Levels ◽  
Measurement And Analysis ◽  
The City

To explore the noise generated by bridges during operational period, the equivalent continuous sound pressure levels of 12 bridges in the city of Ningbo were measured and analyzed. The measured data show that (1) Although the measured sound levels of these bridges meet the requirement of Chinese codes, they are near the maximum limit and the vibration and noise reduction is necessary; (2) A-weighted sound level of bridge is close to that of the road nearby; (3) Z-weighted sound level of bridge is much greater than that of the road nearby, it indicates that the bridge noise contains much low frequency noise, so that A-weighted sound level can’t reflect the noise of bridge accurately, and Z-weighted sound level shall be used to evaluate the acoustic environment near bridges.

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