Noise sickness

Introduction to noise disease Noise refers to the mixing of sounds of different frequencies and different intensities, which can make people upset and difficult to work and rest at rest; in some cases, even awkward music can become an unwelcome The sound, so physiologically speaking, any sound that does not need to affect people's life, work, study, and interference is called noise. Noise mainly damages the human auditory organs. Long-term exposure to high-intensity noise not only damages the auditory organs, but also affects the central nervous system, cardiovascular system, endocrine system and digestive system to varying degrees. Therefore, the noise disease is a systemic disease in which the hearing organ is mainly damaged and accompanied by an auditory external system reaction. basic knowledge The proportion of illness: 0.0005% Susceptible people: no specific population Mode of infection: non-infectious Complications: endocrine disorders

Cause of noise disease

After the long-term effect of noise on the auditory system, high-frequency hearing loss mostly occurs above 2000 Hz. The initial stage is especially affected by 3000-4000 Hz. The possible causes are: the external auditory canal has a resonance effect on the sound of 2000-6000 Hz; The middle ear is more likely to conduct high-frequency sound; the inner ear cochlea has a narrow area at the base, which mainly feels high-frequency sound around 4000Hz. There are anatomical physiological defects, poor blood circulation, and easy to be affected by lymph vibration waves. When the basement membrane is shaken, the amplitude is the largest, and the strong and frequent acoustic load is concentrated here. The lesions of the auger are mostly on the basal part. The pathological examination reveals that the hair cells of the auger are swollen, degenerated, atrophied or disappeared. In severe cases, the spiral is seen from the base. Exfoliation on the membrane, electron microscopy showed swelling of hair cell mitochondria, endoplasmic reticulum hyperplasia, experiments showed that noise can cause increased metabolism of inner ear sensory cells, increased oxygen consumption, resulting in decreased oxygen tension, decreased enzyme activity, affecting hair cell respiration And metabolism, leading to degeneration and necrosis of cells, causing sensorineural deafness.

The nerve impulses caused by sound pass from the inner ear receptor cells to the high-level auditory center of the brain. The neural pathways terminate in the central cortex, and some nerve fibers along the main auditory pathway rise up to the midbrain, ending in the reticular structure. Impulsive transmission to the autonomic nervous system, thereby stimulating changes in the gland, cardiovascular, gastrointestinal, etc., as part of the systemic response, noise acts on the central nervous system, making people's basic physiological processes - the cerebral cortex's excitation and inhibition balance imbalance The cerebral vascular tone can be changed, and the chromatin is dissolved at the edge of the nerve cells. These changes can be restored in the early stage. If it cannot be recovered in time, over time, a strong excitatory foci will be formed, involving the autonomic nervous system and producing neurasthenia.

The hypothesis that noise has an effect on the cardiovascular system is:

1 The body's reactive norepinephrine increases, directly acting on the myocardium and cardiovascular wall, increasing peripheral resistance, causing blood pressure to rise, accompanied by increased adrenaline secretion, causing an increase in heart rate.

2 The release of catecholamine under the action of noise can change the permeability of cell membrane, increase the content of serum magnesium, decrease the content of magnesium in red blood cells and increase the discharge of urinary magnesium. The magnesium in the cell is negatively balanced, which reduces the magnesium in the heart and increases the calcium, and also increases the heart. In addition, the lack of magnesium in the body can also increase the body's sensitivity to noise. Some people think that the acute impact of noise on the auditory system is caused by its direct effect; while the biochemical reactions in the body and some changes in other systems , is considered to be the indirect impact of noise.

In recent years, many studies have found that exposure to noise, such as toluene, which is exposed to organic solvents, or undesirable lifestyles such as smoking can aggravate the chronic damage of the hearing system.

Noise prevention

In 1980, China formulated the "Noise Standard for Noise of Industrial Enterprises" according to the A sound level (for trial implementation), which stipulated that the general allowable standard for noise at the workplace was 85 dB (A).

Controlling and eliminating noise sources is the most fundamental measure to prevent noise hazards. According to the different nature of noise sources, sound insulation, noise reduction, sound absorbing materials, facilities, sound source strength meet national health standards, and individual ear protection equipment is worn. An effective preventive measure, commonly used individual ear protectors have earmuffs, earplugs, disposable soft foam earplugs are the most commonly used, sound insulation effect can reach 20dB ~ 30dB, earmuffs sound insulation effect is better, up to 30dB ~ 40dB.

For patients with obvious auditory organs, cardiovascular and neurological organic diseases, it is not allowed to participate in noise operations. Emphasizing the pre-employment hearing testers is also important to prevent noise damage to the organs.

Noise complications Complications, endocrine disorders

Noise-induced vasoconstriction, heart rate changes, blood pressure fluctuations, endocrine disorders, etc. These are not unique responses to noise, but long-term repeated noise stimuli can cause or promote the occurrence of certain diseases, non-hearing effects caused by noise. There are physiological reactions, such as: cardiovascular, endocrine, respiratory, neurological disorders; psychological reactions, such as fright, personality changes; troubles, such as sleep disruption, interfere with rest; affect language listening, hinder language social; work efficiency and so on.

Noise sickness symptoms common symptoms hearing fatigue hearing loss tinnitus vocal aging

The damage of the noise to the auditory system is mainly manifested by an increase in the hearing threshold and a decrease in the hearing sensitivity.

Noise-induced hearing loss, slow onset. First, from physiological reactions, progressive to pathological damage.

Physiological hearing response process

1 Auditory adaptation: After a short period of exposure to noise, subjective perception of tinnitus and hearing loss, the examination found that the hearing threshold can be increased by 10dB (A) or more, and after a few minutes of leaving the noise environment, it can be restored.

2 hearing fatigue

Staying in a strong noise environment for a long time, the hearing is obviously reduced, the hearing threshold is increased by more than 15dB (A) or even 30dB (A) or more, and it takes a long time (hours to ten hours) to recover the hearing after leaving the noise environment, called the temporary hearing threshold. Displacement is a functional change. If you continue to be exposed to noise, the physiological hearing response can progress to pathological permanent hearing loss. It is difficult to hear a low-pitched speech at a long distance, and then it becomes unclear when it comes to listening to a close voice. When the hearing loss develops to affect the language frequency band (500, 1000, 2000 Hz), the subjective sensory language hearing declines significantly, the daily language communication hearing disorder, the hearing test language band hearing loss is above 25dB, which is the noise . In the early stage of hearing impairment, in addition to many tinnitus, the subjective symptoms are generally not obvious. Most of the hearing tests showed a "V" type depression in the high frequency band of 3000-6000 Hz. Hearing damage is further developed. The "V" type subsidence increases and becomes wider. The hearing curve decreases from low frequency to high frequency, and the slope is decreased. The air conduction and bone conduction hearing are both reduced. Most of them are bilateral symmetry deafness. Generally, the difference is not more than 10dB, unilateral can occur under certain special contact conditions.

Acute noise-induced hearing loss

Acute noise-induced hearing loss, also known as violent deafness, is caused by blasting, firearms or other sudden loud noises. In addition to the strong noise (more than 140dB), there are still shock wave effects, severe tinnitus, headache, hearing loss and symptoms such as dizziness, nausea and vomiting. Physical examination revealed rupture of the tympanic membrane, damage to the ossicular chain, and tympanic and internal ear bleeding. The hearing curve shows a high frequency band (above 2000 Hz) hearing loss, and the degree of decline varies with the condition.

The effects of noise on the external system of hearing can cause psychological and physiological responses and changes in the human body. In a noisy environment, people are upset, their concentration is not easy to concentrate, their response is slow, and their work efficiency is degraded. After exposure to noise, complain of neurasthenia syndrome such as dizziness, headache, tinnitus, palpitations and poor sleep. The survey found that workers exposed to high-intensity noise showed fatigue and irritability. Electroencephalography showed a decrease or disappearance of the alpha rhythm and an increase in beta rhythm. The response of noise to the cardiovascular system is mainly reflected in changes in blood pressure and heart rate. Although the results reported in many studies are inconsistent, most people think that long-term exposure to noise can increase blood pressure, often with diastolic blood pressure. The effect of noise on heart rate, a single noise effect slows down the pulse rate. If noise is combined with systemic vibration, the pulse rate is accelerated. Electrocardiogram examination of the person exposed to noise can be found that the ST segment and T wave show ischemic changes, sinus arrhythmia, tachycardia, and prolonged QRS duration. The reaction of the digestive system to noise may result in decreased secretion of gastric juice, slowing of gastrointestinal motility, loss of appetite, and a thinning of the human body. Noise workers have a higher prevalence of gastric ulcers and more gastrointestinal dysfunction. The effect of noise on endocrine and immune functions is often manifested by increased secretion of catecholamines in human blood, increased excretion of 3-methoxy-4-hydroxymandelic acid (VMA) in urine; and intermittent urine exposure. 17 hydroxycorticosteroid excretion increased. The effect of noise on reproductive function is often manifested as changes in ovarian function and menstrual cycle or menstrual flow of female workers. Domestic studies have shown that the incidence of pregnancy reactions and pregnancy-induced hypertension in women workers in weaving workshops exposed to intense production noise is significantly higher than that of women workers in other workshops.

Noise sickness check

Hearing examination, the permanent hearing threshold displacement is beyond the normal range, the speech frequency hearing is still in the normal range, and the hearing loss is diagnosed as hearing impairment when the hearing loss of any frequency in the high frequency pure tone audiometry of 3000, 4000, 6000 Hz is 30 dB. It is listed as an observation object. On the basis of high-frequency hearing loss, it is found that the mean value of the sum of the hearing loss of the language frequencies of 500, 1000, 2000 Hz is 25 dB, and the diagnosis is noise . The occupational noise has not been officially announced in China. The grading standard, the proposed division principle is: hearing loss of 25 ~ 40dB is mild ; 41 ~ 55dB is moderate ; 56 ~ 70dB is severe ; 71 ~ 90dB is severe ; > 90dB is full .

Diagnosis of noise disease

The diagnosis of the effects of noise-induced extra-auditory systems should be particularly cautious. The effects of inherent diseases and other harmful occupations and the environment must be excluded. Since the influence of noise on the auditory system is non-specific, differential diagnosis is more important. Diagnosis of sexual hearing impairment and noise sputum:

1 exact noise exposure to occupational history;

2 other causes of convulsions, such as infectious diseases, middle ear infections, head trauma, ototoxic drugs, senile sputum;

3 Hearing examination, permanent hearing threshold displacement is beyond the normal range, speech frequency hearing is still in the normal range, and hearing loss is diagnosed as hearing loss when hearing loss of any frequency in high frequency pure tone audiometry of 3000, 4000, 6000 Hz is 30 dB. Protection is listed as the observation object; on the basis of high-frequency hearing loss, it is found that the mean value of the sum of the hearing loss of the language frequencies of 500, 1000, 2000 Hz is 25dB, and the diagnosis is noise . The occupational noise has not been officially announced in China. The grading standard, the proposed division principle is: hearing loss of 25 ~ 40dB for mild sputum; 41 ~ 55dB for moderate sputum; 56 ~ 70dB for severe sputum; 71 ~ 90dB for severe sputum; > 90dB for all sputum.

The diagnosis of the effects of noise-induced extra-auditory systems should be particularly cautious. The effects of inherent diseases and other harmful occupations and the environment must be excluded. Since the influence of noise on the auditory system is non-specific, differential diagnosis is more important.

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