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ioh 2020, 17(1): 908-923 |
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Bamdad M, tokhmchi B, Fazel-Rezai R, mokri C. Investigation of the Effect of Explosion on EEG Signals of Blasting Employees. ioh 2020; 17 (1) :908-923
URL: http://ioh.iums.ac.ir/article-1-2793-en.html
URL: http://ioh.iums.ac.ir/article-1-2793-en.html
Shahrood University of Technology , bamdad@shahroodut.ac.ir
Abstract: (3780 Views)
Background and aims:
Occupational noise is one of the most important causes of occupational accidents and general human error. In addition to being one of the leading causes of hearing loss and tinnitus, it is one of the most effective extrinsic factors affecting brain processing mechanisms. The human response to sound and wave explosions and changes in air pressure is a major concern in the mining. Explosive is used to break the rock and this process is referred to as an integral part of the mining process. However, this cheap method of rock breakage has inherent disadvantages and that too concerning the environment and human safety. Blasting in opencast mines is characterized by the use of large masses of explosives for a single blast. Blasting workers likewise inhabitants in a war zone are continuously exposed to explosions. It is, however, difficult to gauge the effectiveness of certain phenomenon. Physiological response to blast which is particularly transient was evaluated considering ears as the most vulnerable organs. From the survey, it is concluded that ear responses are dependent not only on the pressure but also on impulse and body orientation. It is a fact that the nature and duration of normally generated vibrations are different from that generated by a blast. Moreover, mining blasts are accompanied by higher levels of noise. Under such circumstances, whether vibration standards should be generally applied to blasting in mines is doubtful especially when the mild traumatic is observed in some cases. Almost all studies investigating the effect of the explosion on soldiers’ brain confirmed that soldiers suffer from brain injury resulted in an explosion and sound waves. They give a detailed account of community response to military explosions but there are very few studies relating to this issue which are existing on a direct effect on physiology in general and the brain in particular due to the mining explosion and air-overpressure. The idea of the study is to ascertain any changes in the human brain due to the immediate response in and around mines. This data would be used to predict the effect of the direct impetus on human physiology and the response thereof. In the present study, the brain responses of blasting workers personnel and individuals exposed to explosive noise were investigated.
Methods:
There are some constraints for the tests. (1) Sound conditions can be kept constant only in the test, as there is a significant variation in different parameters involved in the real environment. (2) There is just one EEG device available for recording responses of one person at one time. (3) It is difficult to carry and operate the equipment at places where the actual one is taking place. The experiment we present in this paper compared the intensity of participants' brain responses to acoustic stimuli, an intense burst typically used in the literature. This sound is similar characteristics in terms of duration and intensity that is produced in the real-world by explosions. Due to the complexity of the signal processing and signal processing, this study is an interventional study conducted on five university staff, as a representative of a community that has never been exposed to blast waves and five blasting workers working in different mines. The electroencephalogram (EEG) has great potential for continuous and quantitative human state measurement. EEG is the recording of the electrical signal along the scalp produced by the action of neurons within the brain, which can be measured using electrodes attached to the scalp. The activation of a central nervous system is thus manifested in the EEG signal. Keeping in view the limited available resources and complex analysis of EEG signals, tests are not at a large scale designed to generate data bank. All participants in the experiment ranged in age from 32 to 42 years (mean: 37 years, STD: 1.5 years) and had general physical health. This study was approved by the Institutional Board Review (IRB) of the Shahrood University of Technology, corrective exercise, and rehabilitation laboratory (CRL) according to the approved protocol. Acoustic characteristics and effects of tinnitus were asked through history taking and a brief cognitive status examination was performed for all subjects. For this purpose, brain waves recorded as brain signals (EEGs) were used. Routine EEG signals recorded for 30 s. The EEG signal capture cap was eight-channel, and the channels were positioned so that different subjects' senses, including motor, speech, auditory, visual, and involuntary, were examined. Eight electrodes were selected from Fp1, Fp2, C3, C4, T3, T4, O1, O2 placement on the scalp. A1 and A2 (ear or mastoid electrodes), which are reference and ground electrodes were also connected. The experiment was designed so that the signals were recorded when the explosion sound was broadcasted suddenly without pre-awareness.
Wavelet decompositions were used to investigate how different brain lobes response to explosion sound and to demonstrate differences among responses in different groups of subjects, i.e. surface blasting workers, staff, and miners. A wavelet is a mathematical function used to divide a given function or continuous-time signal into different scale components. Usually one can assign a frequency range to each scale component. Each scale component can then be studied with a resolution that matches its scale. It should be mentioned that in each level of wavelet decomposition, signal divides into two sections: low-frequency band or approximation, and high-frequency band or details; each contains a half frequency band of the signal.
Results:
Different frequency bands of EEG signals are representative of the cognized brain’s behavior. The investigation included an application of time–frequency based method for measuring electroencephalogram (EEG) phase synchronization. The sampling frequency was set to 500 Hz by the hardware although it is higher than what is needed in this project.
EEG signals can be highly contaminated by both extrinsic and intrinsic artifacts that obscure the signal of interest. Extrinsic artifacts are the noises generated mostly from an external source rather than human body physiology such as movement artifacts, environmental noise, and electrical wiring noise in the EEG sensor. To address these issues, the authors successfully tested signal processing framework to acquire high quality EEG signals. After recording the brain signal and the time of the voice transmission in the experiments, the study showed that two superior properties of the signals had to be extracted.
For each subject and each electrode, one feature was gathered. Mentioned features gathered for tests that explosion sound played. It should be mentioned that in some cases feature extraction was impossible because there was not any detectable variability associated with Delta band of the signal, during explosion sound playing. Based on this study, we hypothesized that alterations in the spectral power of the EEG during the presentation of auditory stimuli compared to the rest conditions would differ between individuals with and without experience in blasting works. We analyzed power values in theta, alpha, and beta frequency bands, and tested possible differences between groups in each of the three frequency bands. In all other experiments, reaction duration times of blasting workers and staff were the same. The gradient and timing of the signal variability were monitored following the sound transmission. The reactions of university personnel and blasting workers in some channels of signal reception are similar and in others quite different. In some other channels and senses, the response of non-worker to the sound of the explosion was that the signal level decreased and their motor and auditory consciousness levels decreased, although this was vice versa for blasting workers personnel.
Conclusion:
How job habits influence humans’ behavior? This is a regular question that has investigated frequently. The goal of this paper was to study the behavior of blasting workers, emphasizing their brain signals. Staff were representative of common humanity, do not associated with the explosive issues. Using this algorithm, abnormal features of brain electrical activity were detected. In some cases, workers' EEG signal levels increase, unlike normal people, after hearing the sound of explosions, indicating increased levels of motor, speech, and visual awareness. However, from the perspective of auditory and involuntary senses, no significant difference was observed between two groups.
In some cases there is no effect on the functioning of the brain and physiological response is not observed within the limited range of observations. As a result, no matter they know what will happen, they have gone to be panic when they heard explosion sound. In terms of reaction time to the sound of the explosion, in many cases there was no significant difference between them, except in the motor and speech senses that the response of ordinary people was far faster than the workers. The validity of the EEG-based measurement was examined through a comparison with levels obtained from workers’ samples, which has been accepted as a reliable physical measure of reactions. The results demonstrate the applicability of an EEG signal on measuring workers’ reactions. Particularly in the future works remain crucial to understanding workers’ states. This study can contribute to the knowledge of an in-depth understanding of reactions in the mining field. It shall provide a tool to continuously measure workers’ performance while they are working with explosive material in the mining.
Occupational noise is one of the most important causes of occupational accidents and general human error. In addition to being one of the leading causes of hearing loss and tinnitus, it is one of the most effective extrinsic factors affecting brain processing mechanisms. The human response to sound and wave explosions and changes in air pressure is a major concern in the mining. Explosive is used to break the rock and this process is referred to as an integral part of the mining process. However, this cheap method of rock breakage has inherent disadvantages and that too concerning the environment and human safety. Blasting in opencast mines is characterized by the use of large masses of explosives for a single blast. Blasting workers likewise inhabitants in a war zone are continuously exposed to explosions. It is, however, difficult to gauge the effectiveness of certain phenomenon. Physiological response to blast which is particularly transient was evaluated considering ears as the most vulnerable organs. From the survey, it is concluded that ear responses are dependent not only on the pressure but also on impulse and body orientation. It is a fact that the nature and duration of normally generated vibrations are different from that generated by a blast. Moreover, mining blasts are accompanied by higher levels of noise. Under such circumstances, whether vibration standards should be generally applied to blasting in mines is doubtful especially when the mild traumatic is observed in some cases. Almost all studies investigating the effect of the explosion on soldiers’ brain confirmed that soldiers suffer from brain injury resulted in an explosion and sound waves. They give a detailed account of community response to military explosions but there are very few studies relating to this issue which are existing on a direct effect on physiology in general and the brain in particular due to the mining explosion and air-overpressure. The idea of the study is to ascertain any changes in the human brain due to the immediate response in and around mines. This data would be used to predict the effect of the direct impetus on human physiology and the response thereof. In the present study, the brain responses of blasting workers personnel and individuals exposed to explosive noise were investigated.
Methods:
There are some constraints for the tests. (1) Sound conditions can be kept constant only in the test, as there is a significant variation in different parameters involved in the real environment. (2) There is just one EEG device available for recording responses of one person at one time. (3) It is difficult to carry and operate the equipment at places where the actual one is taking place. The experiment we present in this paper compared the intensity of participants' brain responses to acoustic stimuli, an intense burst typically used in the literature. This sound is similar characteristics in terms of duration and intensity that is produced in the real-world by explosions. Due to the complexity of the signal processing and signal processing, this study is an interventional study conducted on five university staff, as a representative of a community that has never been exposed to blast waves and five blasting workers working in different mines. The electroencephalogram (EEG) has great potential for continuous and quantitative human state measurement. EEG is the recording of the electrical signal along the scalp produced by the action of neurons within the brain, which can be measured using electrodes attached to the scalp. The activation of a central nervous system is thus manifested in the EEG signal. Keeping in view the limited available resources and complex analysis of EEG signals, tests are not at a large scale designed to generate data bank. All participants in the experiment ranged in age from 32 to 42 years (mean: 37 years, STD: 1.5 years) and had general physical health. This study was approved by the Institutional Board Review (IRB) of the Shahrood University of Technology, corrective exercise, and rehabilitation laboratory (CRL) according to the approved protocol. Acoustic characteristics and effects of tinnitus were asked through history taking and a brief cognitive status examination was performed for all subjects. For this purpose, brain waves recorded as brain signals (EEGs) were used. Routine EEG signals recorded for 30 s. The EEG signal capture cap was eight-channel, and the channels were positioned so that different subjects' senses, including motor, speech, auditory, visual, and involuntary, were examined. Eight electrodes were selected from Fp1, Fp2, C3, C4, T3, T4, O1, O2 placement on the scalp. A1 and A2 (ear or mastoid electrodes), which are reference and ground electrodes were also connected. The experiment was designed so that the signals were recorded when the explosion sound was broadcasted suddenly without pre-awareness.
Wavelet decompositions were used to investigate how different brain lobes response to explosion sound and to demonstrate differences among responses in different groups of subjects, i.e. surface blasting workers, staff, and miners. A wavelet is a mathematical function used to divide a given function or continuous-time signal into different scale components. Usually one can assign a frequency range to each scale component. Each scale component can then be studied with a resolution that matches its scale. It should be mentioned that in each level of wavelet decomposition, signal divides into two sections: low-frequency band or approximation, and high-frequency band or details; each contains a half frequency band of the signal.
Results:
Different frequency bands of EEG signals are representative of the cognized brain’s behavior. The investigation included an application of time–frequency based method for measuring electroencephalogram (EEG) phase synchronization. The sampling frequency was set to 500 Hz by the hardware although it is higher than what is needed in this project.
EEG signals can be highly contaminated by both extrinsic and intrinsic artifacts that obscure the signal of interest. Extrinsic artifacts are the noises generated mostly from an external source rather than human body physiology such as movement artifacts, environmental noise, and electrical wiring noise in the EEG sensor. To address these issues, the authors successfully tested signal processing framework to acquire high quality EEG signals. After recording the brain signal and the time of the voice transmission in the experiments, the study showed that two superior properties of the signals had to be extracted.
For each subject and each electrode, one feature was gathered. Mentioned features gathered for tests that explosion sound played. It should be mentioned that in some cases feature extraction was impossible because there was not any detectable variability associated with Delta band of the signal, during explosion sound playing. Based on this study, we hypothesized that alterations in the spectral power of the EEG during the presentation of auditory stimuli compared to the rest conditions would differ between individuals with and without experience in blasting works. We analyzed power values in theta, alpha, and beta frequency bands, and tested possible differences between groups in each of the three frequency bands. In all other experiments, reaction duration times of blasting workers and staff were the same. The gradient and timing of the signal variability were monitored following the sound transmission. The reactions of university personnel and blasting workers in some channels of signal reception are similar and in others quite different. In some other channels and senses, the response of non-worker to the sound of the explosion was that the signal level decreased and their motor and auditory consciousness levels decreased, although this was vice versa for blasting workers personnel.
Conclusion:
How job habits influence humans’ behavior? This is a regular question that has investigated frequently. The goal of this paper was to study the behavior of blasting workers, emphasizing their brain signals. Staff were representative of common humanity, do not associated with the explosive issues. Using this algorithm, abnormal features of brain electrical activity were detected. In some cases, workers' EEG signal levels increase, unlike normal people, after hearing the sound of explosions, indicating increased levels of motor, speech, and visual awareness. However, from the perspective of auditory and involuntary senses, no significant difference was observed between two groups.
In some cases there is no effect on the functioning of the brain and physiological response is not observed within the limited range of observations. As a result, no matter they know what will happen, they have gone to be panic when they heard explosion sound. In terms of reaction time to the sound of the explosion, in many cases there was no significant difference between them, except in the motor and speech senses that the response of ordinary people was far faster than the workers. The validity of the EEG-based measurement was examined through a comparison with levels obtained from workers’ samples, which has been accepted as a reliable physical measure of reactions. The results demonstrate the applicability of an EEG signal on measuring workers’ reactions. Particularly in the future works remain crucial to understanding workers’ states. This study can contribute to the knowledge of an in-depth understanding of reactions in the mining field. It shall provide a tool to continuously measure workers’ performance while they are working with explosive material in the mining.
Keywords: Consciousness Level, Electroencephalography (EEG) signals, Explosion Sound, Reaction Time, Signal Gradient
Type of Study: Research |
Subject:
Noise
Received: 2019/05/7 | Accepted: 2020/03/16 | Published: 2020/09/23
Received: 2019/05/7 | Accepted: 2020/03/16 | Published: 2020/09/23
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