An unusual sensation, which is perceived by our ear as sound, is the action of various kinds of vibrations, the so-called dense medium, in particular air, on the hearing aid.

But not all vibrations that occur in the environment cause the sensation of sound. The lowest frequency range at which the hearing aid is able to recognize sound is 20 hertz.

The highest threshold is around 16 or 20 thousand hertz. The definition of these boundaries depends on individual changes.

Ultrasound when exposed to human body , is able to transform into thermal energy, which causes a feeling of warmth when exposed to it. It causes the so-called micro tissue massage (its compression and stretching), which favorably affects blood circulation, which subsequently improves tissue functions.

When exposed to are improving metabolic processes organism, as well as ultrasound provides some neuro-reflex effect.

Changes after exposure to ultrasound are noted not only in the place where ultrasound was specifically applied, but also in other parts of the body. With prolonged exposure, ultrasound can lead to some tissue destruction.

Experts believe that its destructive action is due to the so-called cavitation effect. This effect leads to the formation of cavities in the fluid, leading to cell death.

Such cavities have been identified in animal experiments. The results show that receipt vesicles formed in the intercellular space.

Ultrasound can kill many types of microorganisms. Able to inactivate certain types of viruses. It negatively affects the structure of proteins, disrupting it and eventually destroying it completely. When exposed to ultrasound on milk, which destroys its property, completely destroys the content of vitamin C in it.

In medicine, ultrasound is used in sounding blood, which leads to an increase in its coagulation properties. We can say that ultrasound suffocates the cells of the body. Because of it, the cell cannot breathe normally and produce its metabolic processes.

Animal experiments show that intense exposure to ultrasound leads to severe pain, alopecia, some burns, clouding of the cornea of ​​​​the eye and lens, serious violations of the biochemical nature, hemolysis, and exposure to high frequencies, death occurs due to small hemorrhages in various organs of the body

Experimental data show that ultrasound can seriously affect hearing aid sensitivity. Experts believe that a large percentage of the United States population with hearing impairment is associated with exposure to sound installations that are widespread throughout the country.

Persons who have been exposed to ultrasound for a long time feel some drowsiness and fatigue.

It is contraindicated to sound a growing organism, genitals, heart. This can cause extremely negative consequences associated with impaired cardiovascular activity. The use of ultrasound is also contraindicated in certain diseases, as well as during pregnancy.

Due to the increasing use of ultrasound, some people are unwittingly exposed to it. To prevent negative changes in the body, one should undergo examinations and, in the presence of ultrasound exposure, take preventive measures to neutralize further changes.

Ultrasound therapy, or ultrasound therapy, is a treatment technique using ultrasound. Ultrasound therapy is used in physiotherapy for the treatment and prevention of various diseases. The technique is used in various fields of medicine, such as orthopedics, surgery, gynecology, ophthalmology, dermatology, otolaryngology, dentistry, and pediatrics. Ultrasound therapy can reduce the frequency of exacerbations, as well as reduce the recovery time after surgery, acute pathologies.

Historical information

Ultrasonic waves were discovered in 1899 by K. Konig. The Russian engineer K. V. Shilovsky and the French inventor Langevin tried to use ultrasound in practice in 1914-1918. The research of these scientists led to the creation of an ultrasound emitter. He worked on the basis of the piezoelectric effect, in accordance with the development of the Curie brothers. After that, a device based on magnetostriction was made. Over time, the beams emanating from the apparatus became more directed towards a specific object. This allowed the use of ultrasonic waves in industry and medicine.

Ultrasound began to be used in medicine after 1927. The impetus for the use of ultrasound was the work of scientists on the biological effects of ultrasound on the body. It is believed that R. Polman was the first to use ultrasound. He created a vibrator that emits ultrasonic waves. Polman treated sciatica, neuralgia, myalgia with ultrasound waves. The results of treatment were positive.

By 1945, ultrasound began to be used in Germany, Western Europe, the USA, and Japan. In our country, the technique began to be applied only in 1953. Scientist V. A. Plotnikov first tried to treat Dupuytren's contracture with ultrasound. In 1955, ultrasonic waves began to be used in the treatment of neurological, articular pathologies, and skin diseases.

Starting from 1961, they began to produce domestic ultrasonic devices. Their production was serial, which served as an impetus for the development of ultrasound therapy. In 1986, scientists from Belarus (L. I. Bogdanovich, V. S. Ulashchik, A. A. Chirkin) were awarded a prize in the field of science and technology. Methods of ultrasound therapy in physiotherapy are widely used today for the treatment of various diseases.

Characteristics of ultrasonic waves

For physiotherapeutic procedures, ultrasonic waves with a frequency of 800-3000 kHz are used. For surgical manipulations, the oscillation frequency is 20-100 kHz. The dosage of ultrasonic impact on the body depends on the intensity, duration of exposure, as well as the type of generation of ultrasonic waves (continuous, pulsed).

Intensity of ultrasonic waves:

• Low (no more than 0.4 W/cm2).
• Medium (0.5-0.8 W / cm2).
• High (0.9-1 W/cm2).

With continuous exposure to ultrasound, ultrasonic waves are sent to tissues without stopping. Impulse impact on the organs is an interrupted stream of waves with a duration of 2.4 or 10 ms.

The degree of absorption of ultrasonic waves depends on acoustics and vibration frequency. If the tissues are soft, then absorption will occur at a depth of 4-5 cm at a frequency of 800-900 kHz, at a depth of 1.5-2 cm at a frequency of 3000 kHz.

Absorption of tissues in relation to blood:

• fatty - 4 times more effective;
• muscular - 10 times better;
• bone - 75 times more intense.

At the crossing point various kinds tissues, the intensity of absorption of ultrasonic waves is much higher. In the air, they are immediately absorbed, therefore, various media are used for ultrasonic physiotherapy.

Mechanism of exposure to ultrasonic radiation

There are several mechanisms of the impact of ultrasound on the body. These include: mechanical, thermal, physico-chemical, neuro-reflex. They are the primary mechanisms of ultrasound therapy.

The mechanical effect consists in high-frequency vibrations that are transmitted to the tissues.

In this case, a very small vibration, imperceptible to a person, occurs. Vibration effect leads to an increase in blood circulation, an increase in metabolism in cells.

Under the action of vibration in the cell, the viscosity of the cytoplasmic fluid decreases. The tissues begin to loosen connective tissue. Diffusion of trace elements is accelerated in cells, the work of lysosomes is stimulated. Enzymes begin to come out of lysosomes, which increase the function of protein compounds. These processes contribute to the acceleration of metabolism. When high-frequency waves are applied, the permeability of histohematic barriers increases.

The thermal effect implies the transition of the energy of ultrasonic waves after absorption by tissues into heat. The temperature in them increases by 1°C. At the same time, enzymatic activity inside tissues is accelerated, biochemical reactions are stimulated. Heat is generated only at the boundaries of tissues of different density. Thermal energy is more absorbed by organs with a lack of blood flow, saturated with collagen fibers, as well as nervous and bone tissue.

The physico-chemical effect is caused by mechanical resonance. It increases the speed of movement of molecular structures, the process of disintegration of molecules into ions increases, new electric fields appear. The oxidation of lipids is accelerated, the work of mitochondrial cell structures improves, physical and chemical processes in the tissues of the body are stimulated. Biologically active substances such as histamine and serotonin are activated. Under the influence of ultrasonic waves, respiration and oxidation in the organs improves. All these processes accelerate tissue repair.

The following phases of the body's reaction are distinguished:

Therapeutic effect of ultrasound waves

Ultrasound waves are a specific stimulus when they act on organs and tissues. If the effect of ultrasound is directed to the skin, then an inflammatory reaction is formed, redness of the skin, and metabolism increases. During ultrasound therapy (UST), the number of mast cells increases, the function of cambial (stem) cell structures is stimulated, and the concentration of mucopolysaccharides increases. Against the background of therapy, the function of the glandular apparatus (sebaceous sweat glands) in the skin increases, the reaction of the skin to stimuli becomes brighter.

The tissues of the nervous system are very sensitive to the effects of ultrasonic waves. Ultrasound inhibits the work of synaptic cleft receptors, which helps to reduce the transmission rate nerve impulses. Improving general state in patients with disorders of the autonomic nervous system.

If the ultrasound waves act on the area of ​​the glands, this leads to stimulation of the synthesis of hormones. Increases immune activity.

When exposed to the cardiovascular system, ultrasound can increase blood flow, slightly lower blood pressure, increase the frequency heart rate. The rheological properties of blood become better, the function of erythrocytes and leukocytes increases.

Indications and restrictions for the appointment of ultrasound

The ultrasound procedure has its indications and limitations.

During the application of the ultrasound method of treatment, the emitter should not be directed to the region of the heart, brain, bone growth points in children.

Ultrasound technique and devices

When conducting ultrasonic physiotherapy, it is necessary to eliminate purulent foci of infection. This can be done using medicines and disinfectant solutions. should also be treated infectious diseases viral or bacterial.

The physiotherapy algorithm is as follows. Before starting therapy, the skin at the point of contact with the apparatus head of the emitter must be lubricated with a special substance (vaseline, lanolin). Turn on the device, adjust the intensity of the waves, set the time. After that, the emitter is installed in the required area on the surface of the skin and they begin to drive at a speed of 1 cm per second.

At the initial stage of treatment, no more than 1-2 fields can be processed in 1 session. After two days of treatment, up to 3-4 fields can be irradiated. The duration of the procedure in the first two days should not exceed 5 minutes. The duration of subsequent sessions is up to 15 minutes. For children, the procedure is recommended to be carried out no more than 10 minutes.

When treating limbs (feet, hands, joints, forearm, lower leg) with ultrasound, the procedure is carried out in water. The patient lowers his arm or leg into the bath, and the emitter is immersed there. Temperature regime for water is 32-36°C. The duration of the physiotherapy is up to 15 minutes.

During therapy, the safety of medical personnel must be ensured. The nurse who holds the emitter in the water should put on a woolen glove and a rubber glove on top of it. This protects the healthcare worker's hand from ultrasonic exposure to the hand. A wool mitten has air in its pores, which completely absorbs ultrasonic waves.

Types of devices used in institutions:

• For physiotherapy - UZT-1.01F.
• In dentistry - UZT-1.02S.
• For urology - UZT-1.03U.
• For eye diseases - UZT-1.04O.
• For women - UZT-3.01-G.
• In dermatology - UZT-3.02-D.
• For a child (skin irradiation) - UZT-3. 06.
• General purpose - UZT-3. 05.

Today, the following devices are also produced: Gamma, Barvinok, Rod, Prokton-1, Geniton, LOR-3, Sonostat, Sonopuls, ECO, ECOSCAN. To conduct ultrasound therapy at home, you can purchase an ultrasound machine in medical equipment stores. For home use, the Reton device is perfect.

Before using an ultrasonic device, you must always consult a doctor. The doctor will conduct a complete examination. This is very important, since ultrasound therapy is not allowed for all patients.

Ultrasound in children

Ultrasound therapy for children is prescribed only from the age of 7. In more early age method should not be used. Therapy is used for the same indications as for adults.

In adolescent girls, ultrasound is used to treat a disorder menstrual cycle. Patients younger age ultrasound is indicated for adenoiditis and other ENT pathologies. Children also need ultrasound treatment for bedwetting. Ultrasonic waves improve tissue condition Bladder, which helps to form a normal urination reflex, reduce the reactivity of the bladder.

Conclusion

Ultrasound therapy is a relatively safe treatment method. It is used when various diseases. It is allowed to apply the ultrasound treatment technique to hospitals, as well as sanatorium-and-spa institutions. For ultrasound therapy, you must definitely consult a doctor. He will determine the duration of the sessions, the intensity of exposure to ultrasonic waves, the duration of the course.

The human ear can pick up such sounds, the frequency of which varies from 16 to 20,000 vibrations per second.

Infrasound is a low-frequency sound wave (that is, with a frequency below 16 oscillations), ultrasound is a high-frequency sound wave with a frequency of over 20 thousand oscillations. They are not perceived by the human hearing aid, and the use of special instruments is required to detect them.

It was a huge number of studies that analyzed the signs of a sound wave and the impact of ultrasound that contributed to the emergence of the prerequisites that made it possible to use ultrasound on a large scale in various industries, in the production of individual medicines, in medicine, physics, modern military equipment, biology, national economy and Everyday life. Let us consider in more detail the effect of ultrasound on the human body.

What is ultrasound?

The effect of ultrasound and infrasound on the human body is unique. Ultrasound is a high frequency sound wave that can propagate in solid materials, in liquids and in gaseous media, due to the influence of elastic forces. The origin of ultrasound can be both natural and artificial. So, in nature there are sense organs that allow you to reproduce and receive vibrations generated by an ultrasonic wave, for example, in dolphins, bats, butterflies, whales, locusts, grasshoppers, crickets, certain types of fish and birds.

Thanks to this, they are able to perfectly navigate in space, including at night, as well as communicate with relatives. Dolphins and whales can send the necessary signals for tens of thousands of kilometers. In addition, dogs and cats can pick up ultrasound. The intensity and speed of propagation of ultrasound are directly affected by the characteristics of the substance in which it is transmitted: if it moves away from a source in the air, then the sound weakens rather quickly. In liquids, as well as when passing through a solid, the strength of ultrasound decreases slowly. What is the effect of ultrasound on the human body?

Difference from normal sound

It differs from ordinary sound in that it propagates in all directions from the source. Ultrasound is essentially a wave in the form of a narrow beam. Such features allow it to be used for the study of the sea and ocean floor, the detection of sunken ships and submarines, as well as various obstacles under water, and the exact distance.

But when propagating in water, ultrasonic waves can harm those organisms that live in it. Under the influence of ultrasound, the fish's sense of balance is disturbed, they float to the surface of the water upside down, and therefore cannot take their normal position. If the exposure to ultrasound is intense and prolonged, exceeds the permissible limits, then in the end it will cause very serious damage and even death to the fish. If its influence is temporary, and the intensity is not too high, after its termination, the way of life and the behavior of the fish return to their usual limits.

The effect of ultrasound on the human body

Ultrasound affects the human body in a similar way. During the experiment, water was poured into a bowled palm, after which the subject immersed it in the ultrasonic space. At the same time, he experienced painful discomfort. Not everyone knows what effect ultrasound has on the human body.

It should be noted that the essence of the biological effect of ultrasound has not yet been fully studied. But it is more likely to be based on local pressures that occur in the tissues, as well as a local thermal effect, which is directly related to the energy absorption that occurs when vibrations are suppressed. Since gaseous and liquid media are excellent at absorbing ultrasound, while solids conduct it, the skeletal system of the human body is also a good conductor. Ultrasonic exposure in the human body primarily provokes the appearance of a thermal effect, which is a consequence of the energy transformation of an ultrasound wave into heat. What else do you need to know about ultrasound and its effect on the human body?

Stimulates blood circulation

In addition, it causes microscopic stretching and contraction of the tissue (this is called micromassage), and also stimulates blood circulation. In this regard, there is an improvement in the functioning of various tissues of the human body and blood flow. In addition, ultrasound can have a stimulating effect on the course of metabolic processes and reflex-nervous action. It promotes changes not only in the organs it affects, but also in other organs and tissues.

Harm of Intense Influence

At the same time, intense and prolonged influence destroys cells and leads to their death. This is due to the fact that cavities are formed in body fluids under the influence of ultrasound (this phenomenon is called cavitation), which causes tissue death. The ultrasound wave can also destroy many microorganisms, and this contributes to the inactivation of viruses such as encephalitis or poliomyelitis. The influence of ultrasound on a protein causes a violation of the structure of its constituent particles and their further disintegration. In addition, it destroys erythrocytes and leukocytes in the blood, its coagulability and viscosity increase significantly, and ROE is also accelerated. The ultrasound wave has a depressing effect on cellular respiration, reduces the amount of oxygen consumed by it, and causes the inactivation of a number of hormones and enzymes.

So the impact on the human body of ultrasound is still not very good.

Consequences for the human body

High-intensity ultrasound can cause the following effects in humans:

The appearance of increased pain syndrome;

Baldness;

Clouding of the lens and cornea of ​​the eye;

An increase in the content of lactic and uric acid, cholesterol in the blood;

Small hemorrhages in a number of organs and tissues of the body;

Significant hearing impairments;

Pathological formation and destruction of bone tissue;

Destruction of nerve cells and cells These are the main diseases caused by exposure to ultrasound.

As a result of prolonged exposure to ultrasound, excessive drowsiness, dizziness, high fatigue, symptoms of vegetovascular dystonia (sleep disorders, memory defects, apathy, indecision, decreased appetite, fearfulness, a tendency to depression, etc.) appear.

Where is the effect of ultrasound on the body most often used?

The use of ultrasound in the field of medicine

The therapeutic effect of ultrasound is due to its ability to penetrate into tissues, their heating and micromassage. It should be noted that ultrasound probably has a number of specific effects, since deep tissue heating is also achieved by other methods, but in some cases a positive effect occurs only after using ultrasound.

Taking into account the reflex mechanism, ultrasound can be used not only to directly affect the epicenter of pain, but also to influence indirectly.

Due to the properties mentioned above, ultrasound under a number of conditions is able to have a bactericidal, antispasmodic, anti-inflammatory and analgesic effect. The use of ultrasound can be combined with other therapeutic techniques. Due to the increased biological activity, care must be taken when treating with ultrasound. Positive results in its therapeutic use have been obtained in a number of diseases. It is very effective in the treatment of neuralgia, myalgia, neuritis of amputated limbs, periarthritis, arthritis and arthrosis. Whether ultrasound is harmful to humans is of interest to many.

General impact

The general effect of ultrasound on the human body is confirmed, in particular, by the fact that when a number of joints are affected, it is often sufficient to limit oneself to the therapy of any of them, since a parallel improvement of the remaining joints is noted. Positive results have been obtained in the treatment with ultrasound of spondylitis, Bechterew's disease, varicose, sluggishly granulating and trophic ulcers, obliterating endarteritis.

There are separate indications of the positive use of ultrasound in bronchial asthma, ulcer duodenum and stomach, bronchiectasis, pulmonary emphysema, Meniere's disease and otosclerosis. There are also observations that indicate that skin pre-sounding enhances the effectiveness of X-ray irradiation.

Contraindications to the use of ultrasound

It is forbidden to sound the genitals, growing bones, tumors, heart areas (this can cause angina pectoris). At hypertension, pulmonary tuberculosis, pregnancy, hyperthyroidism, changes in parenchymal organs, the use of ultrasound is also contraindicated. If it is applied on an ever larger scale, then it is necessary to organize careful monitoring of patients who are in contact with ultrasound in order to identify early symptoms of the disease and take the required preventive and preventive measures in time. medical measures. There is also evidence of a positive effect of ultrasound on some forms of neuritis and cancer. But the width of the safe area between the positive and damaging effects has not yet been determined with accuracy.

We examined the effect of ultrasound on the human body.

INFLUENCE OF ULTRASOUND ON THE HUMAN BODY

At present, ultrasound is widely used in various fields technology and industry, especially for analysis and control: flaw detection, structural analysis of a substance, determination of the physicochemical properties of materials, etc.

Technological processes: cleaning and degreasing of parts, machining of hard and brittle materials, welding, soldering, tinning, electrolytic processes, acceleration of chemical reactions, etc. use low-frequency ultrasonic vibrations (LF) - from 18 to 30 kHz and high power - up to 6-7 W / cm 2. The most common sources of ultrasound are piezoelectric and magnetic transducers. In addition, under production conditions, low-frequency ultrasound is often formed during aerodynamic processes: the operation of jet engines, gas turbines, powerful pneumatic motors, etc.

Ultrasound has received significant distribution in medicine for the treatment of diseases of the spine, joints, peripheral nervous system, as well as for performing surgical operations and diagnosing diseases. American scientists have developed effective method removal of brain tumors (2002) that are not amenable to conventional surgical treatment. It is based on the principle used in cataract removal - fragmentation of a pathological formation with focused ultrasound. For the first time, an apparatus has been developed that can create ultrasonic vibrations of the required intensity at a given point without damaging the surrounding tissues. Sources of ultrasound are located on the patient's skull and emit relatively weak vibrations. The computer calculates the direction and intensity of the ultrasonic pulses in such a way that they merge with each other only in the tumor and destroy tissues.

In addition, doctors have learned how to re-grow lost teeth using ultrasound (2006). As researchers from the Canadian University of Alberta found, low-intensity pulsed ultrasound stimulates the re-growth of knocked out and fallen teeth. Doctors have developed a special technology - a miniature “system on a chip”, which ensures the healing of dental tissue. Thanks to the wireless implementation of the ultrasound transducer, the microscopic device, complete with biologically compatible materials, is placed in the patient's mouth without causing him discomfort.

Diagnostic ultrasound has been intensively used for three decades during pregnancy and in diseases of individual organs. Ultrasound, bumping into an obstacle in the form of human or fetal organs, determines their presence and size.

British researchers at the University of Leicester have applied ultrasonic technology to an automated machine that takes measurements from a customer to tailor-make clothes. In the installation, an ultrasound source and sixty sensors register the signals reflected by the body surface.

For these purposes, high frequency (HF) sound vibrations (HF) - from 500 kHz to 5 MHz and low power - from 0.1 to 2.0 W / cm 2 are used in technology. The intensity of the applied therapeutic ultrasound most often does not exceed 0.2-0.4 W/cm 2 ; the frequency of ultrasound oscillations used for diagnostics ranges from 800 kHz to 20 MHz, the intensity varies from 0.01 to 20 W / cm 2 or more.

These are just some of the applications of ultrasound. Man is exposed to it in all cases. How does ultrasound affect the human body? Is it harmful?

Ultrasound is mechanical vibrations of an elastic medium propagating in it in the form of variable compressions and rarefactions; with a frequency above 16-20 kHz, not perceived by the human ear.

With an increase in the frequency of ultrasonic vibrations, their absorption by the medium increases and the depth of penetration into human tissues decreases. Absorption of ultrasound is accompanied by heating of the medium. The passage of ultrasound in a liquid is accompanied by the effect of cavitation. The ultrasound generation mode can be continuous and pulsed.

In addition to the general effect on the body of those working through the air, low-frequency ultrasound has a local effect when it comes into contact with workpieces and media in which ultrasonic vibrations are excited. In the zone of greatest impact of ultrasound, depending on the type of equipment, there are hands. Local action can be permanent (holding the tool with the workpiece during tinning, soldering) or temporary (loading parts into baths, welding, etc.).

Impact from powerful installations (6-7 W / cm 2) is dangerous, because it can lead to damage to the peripheral nervous and vascular apparatus at the points of contact (vegetative polyneuritis, rifling of the fingers, hands and forearm). The contact effect of ultrasound most often occurs at the time of loading and unloading parts from ultrasonic baths. A three-minute immersion of the fingers in the bath water with a converter power of 1.5 kW causes a tingling sensation, sometimes itching, and after 5 minutes. after the cessation of the action of ultrasound, a feeling of cold, a feeling of numbness of the fingers is noted. Vibration sensitivity is sharply reduced, pain sensitivity in different individuals can be either increased or decreased. Short-term systematic contact with the sounded environment lasting 20-30 s or more on such installations can already lead to the development of vegetative polyneuritis phenomena.

Consequences of exposure to ultrasound on the body: functional changes in the central and peripheral nervous system, cardiovascular system, auditory and vestibular analyzer, endocrine and humoral abnormalities; headaches with predominant localization in the frontonasal orbital and temporal regions, excessive fatigue; feeling of pressure in the ears, unsteady gait, dizziness; sleep disturbance (drowsiness during the day); irritability, hyperacusis, hyperosmia, fear of bright light, increased pain excitability thresholds; under conditions of exposure to intense ultrasound, accompanied by noise, - insufficiency vascular tone(downgrade blood pressure, hypotension), disinhibition of skin-vascular reflexes in combination with a bright vasomotor reaction; general cerebral disorders; vegetative polyneuritis of the hands (less often of the legs) of varying degrees (pastosity, acrocyanosis of the fingers, thermoasymmetry, sensitivity disorder like gloves or socks); an increase in body and skin temperature, a decrease in blood sugar levels, eosinophilia. The severity of pathological changes depends on the intensity and duration of the action of ultrasound; contact with the sounded environment and the presence of noise in the spectrum also worsen the state of health.

Compared to HF noise, ultrasound has a noticeably weaker effect on auditory function, but causes more pronounced deviations from the norm in terms of vestibular function, pain sensitivity and thermoregulation. Intense HF ultrasound, upon contact with the body surface, causes basically the same disturbances as LF.

Particular attention should be paid to diagnostic ultrasound. Kruskal's review Diagnostic Imaging in Pregnancy (2000) notes that ultrasound waves have the potential to damage biological tissues through heating and cavitation. However, documented evidence biological effects no ultrasound yet. The Canadian Society of Obstetricians and Gynecologists noted in a 1999 statement that there is no scientific evidence of a damaging effect of diagnostic ultrasound on a developing fetus. It has previously been suggested that exposure to ultrasound may be associated with low birth weight, dyslexia, increased incidence of leukemia, solid tumors, and delayed learning to read and write. Risk ultrasound consists mainly in possible overdiagnosis or the probability of missed pathology.

Permissible sound pressure levels of ultrasonic installations should be taken in accordance with the “Sanitary norms and rules for working on industrial ultrasonic installations” No. 1733-77, GOST 12. 1. 001-89, SanPiN 2. 2. 2/2. 1. 8. 582, which are given for 1/3 octave bands in the frequency range 1.25-100 kHz and are 80 - 110 dB. During contact action, the level of ultrasound should not exceed 110 dB. GOST provides for changes in the remote control of ultrasound with a total reduction in the time of its exposure (by 6 dB with an exposure time of 1 ... 4 hours per shift and 24 dB with an exposure time of 1 ... 5 minutes).

The prevention of the harmful effects of ultrasound is based on technological measures: the creation of automatic ultrasonic equipment (for washing containers, cleaning parts), remote-controlled installations; transition to the use of low-power equipment. In this case, the intensity of ultrasound and noise decreases by 20-40 dB (for example, during ultrasonic cleaning of parts, soldering, drilling, etc.).

When designing ultrasonic installations, it is advisable to choose operating frequencies that are as far away from the audible frequency range as possible (not lower than 22 kHz) in order to avoid the effect of pronounced HF noise.

Ultrasonic installations with noise and ultrasonic levels exceeding the standards should be equipped with soundproofing devices (casings, screens) made of sheet steel or duralumin coated with sound-absorbing materials (roofing material, technical rubber, plastic, anti-vibration, getinax, anti-noise mastic). Soundproof shelters of ultrasonic units must be isolated from the floor with rubber gaskets and not have slots and holes.

Installations generating oscillations with general level 135 dB, placed in soundproof cabins. To exclude the effect of ultrasound in contact with liquid and solid media, it is necessary to turn off the ultrasonic transducers; use of a special working tool with a vibration-isolating handle and protection of hands with rubber gloves with a cotton lining. At elevated level vibration velocity in the frequency range from 8 to 2000 Hz on the surfaces of ultrasonic tools (soldering irons, welding guns, etc.) and devices for fixing parts, it is necessary to resort to damping coatings.

Installations are located in isolated rooms; separated by partitions for the entire height of the room; are fenced in the form of cabins, boxes, enclosures in order to reduce noise and ultrasound at workplaces to acceptable values. ; workers should use personal protective equipment.

When using high-frequency ultrasound, measures should be aimed at protecting the hands of workers. When working in a liquid environment in a laboratory or when performing underwater massage in physiotherapy rooms, contact with the liquid must be completely excluded. During flaw detection, workers should avoid touching the hands with the piezoelectric element of the flaw detection equipment.

The manufacturer must indicate in the operational documentation of the production equipment the ultrasonic characteristic - sound pressure levels in one-third octave bands of the accepted frequency range, measured at control points around the equipment; operating mode in which the determination of the characteristics of ultrasound should be carried out. Working with ultrasonic equipment are instructed on the nature of the action of ultrasound; protective measures; conditions for the safe maintenance of ultrasonic installations.

Contraindications for employment: chronic diseases central and peripheral nervous system, neuritis, polyneuritis; general and vascular neuroses; previous trauma of the skull (concussion); metabolic and endocrine disorders; labyrinthopathy and chronic diseases of the organ of hearing; persistent hearing loss of any etiology; hypotension and hypertension. Periodic medical examinations should be carried out once a year with the participation of a neuropathologist, therapist, otolaryngologist; it is important to study the vestibular apparatus.

Thus, ultrasound, on the one hand, is widely used in many areas of the economy, on the other hand, its effect on the human body during therapeutic use has not yet been sufficiently studied. Patients of clinics undergoing diagnostics of diseases using ultrasound are poorly informed about possible harm health. At least educational work should be carried out in this direction.

Ultrasounds are mechanical vibrations of an elastic medium that have the same physical nature as sounds, but exceed the upper threshold of audible frequency (over 20 kHz). Low-frequency ultrasounds (frequency - tens of kilohertz) have the ability to propagate in the air, high-frequency (frequency - hundreds of kilohertz) - quickly fade. In elastic media - water, metal, etc. - ultrasound propagates well, and the propagation velocity is significantly affected by the temperature of these media.

Ultrasound is often found in nature, accompanying the rustle of leaves, the sound of the surf, etc. In the animal world, it performs a number of vital functions: echolocation of bats, insect signals, etc.

In the mechanism of action of ultrasound on inanimate and living objects, mechanical, thermal and physico-chemical effects take place. The mechanical effect is due to the nature of ultrasound (compression - tension), the thermal effect is due to the transition of mechanical energy into thermal energy, which is especially enhanced at the interface between two media: solid - liquid, liquid - gases, etc. Physicochemical effects are associated with the fact that during propagation Ultrasound in liquids, the so-called cavitation occurs - the appearance of compression and rupture zones due to the movement of elastic waves, which causes the formation of bubbles filled with liquid vapor and gas dissolved in it. When the waves pass, they disappear: in this case, the temperature rises and pressure develops (up to millions of atmospheres). This is accompanied by the appearance of electric charges, luminescent glow, ionization. In water, hydroxyl radicals, atomic hydrogen (H 2 O - HO + H) are formed. With contact sounding, ultrasound causes the inactivation of enzymes, the breakdown of proteins, the acceleration of chemical reactions, and at high energies, burns and the death of living organisms.

Ultrasound has found wide application in medicine for the diagnosis and treatment of many diseases. In engineering and industry, high-frequency ultrasound is used for flaw detection of castings, welds, plastics and physical and chemical studies of substances - determining density, elasticity, structure, etc. Low-frequency ultrasound is used for washing, degreasing, emulsification, grinding solids in liquids, for cutting, metal welding, crushing, drilling of brittle materials, etc. Industrial installations operate mainly at frequencies of 16-44 kHz (less often up to 80).

Under production conditions, short-term and periodic contact exposure to ultrasound occurs when holding a tool, a workpiece, loading products into baths, unloading them, and other operations. With systematic prolonged contact with ultrasound sources, medical workers were observed occupational diseases- paresis of the hands and forearms.

Changes in the state of health of those working with the air transmission of ultrasound are the result of the simultaneous action of ultrasound and noise, the intensity of which in the frequency range of 8-16 kHz can reach 100 dB or more. During ultrasonic cleaning of parts, the air environment is often contaminated toxic substances- vapors of gasoline, acetone, toluene, etc. Health disorders are manifested mainly in the form of asthenic-vegetative reactions with complaints of headache, sleep disorder, irritability, fatigue and objective signs of hearing loss, vestibular disorders, etc.

8.3. Vibration and its effect on the human body

Vibration as an industrial hazard is a mechanical oscillatory movement, directly transmitted to the human body or its individual parts. Due to the mechanization of many types of work and the use of pneumatic and electric tools, its importance has increased dramatically, and at present vibration disease occupies one of the first places among occupational diseases.

With regard to the danger of vibration disease, vibration with a frequency of 16-250 Hz is of the greatest importance.

It is customary to distinguish local (local) and overall vibration: the first is transmitted to the hands or other limited areas of the body, the second - to the whole body (staying on an oscillating platform, seats).

The effect of vibration on workers is often combined with the influence of other industrial hazards: noise, cooling microclimate, uncomfortable body position.

The effect of vibration on the body. Vibration, depending on its parameters (frequency, amplitude), can have both positive and negative effects on individual tissues and the body as a whole. With a physiotherapeutic purpose, vibration is used to improve trophism, blood circulation in tissues in the treatment of certain diseases. but industrial vibration, being transmitted to healthy tissues and organs and having a significant amplitude and duration of action, it turns out to be a harmful influencing factor.

Vibration causes primarily neurotrophic and hemodynamic disorders. In vessels of small caliber (capillaries, arterioles), spastic-atonic conditions arise, their permeability increases, and nervous regulation is disturbed. Vibration, temperature and pain sensitivity of the skin changes. When working with a hand-held power tool, a “dead finger” symptom may occur: loss of sensitivity, whitening of fingers, hands. Workers complain of cold hands aching pain in them after work and at night. The skin between attacks has a marble appearance, cyanotic. In some cases, swelling, skin changes on the hands (cracks, coarsening), hyperhidrosis of the palms are found. Osteoarticular and muscular changes are characteristic. Dystrophic processes cause a change in the structure of bones (osteoporosis, overgrowth, etc.), muscle atrophy. Possible deformation of the carpal, ulnar, shoulder joints with impaired musculoskeletal function.

The disease is of a general nature, as evidenced by fatigue, headaches, dizziness, and irritability. There may be complaints of pain in the region of the heart and stomach, increased thirst: weight loss, insomnia. Astheno-vegetative syndrome is accompanied by cardiovascular disorders: hypotension, bradycardia, ECG changes. During a medical examination, changes in skin sensitivity, tremor of the hands, tongue and eyelids can be detected.

When exposed to general vibration, changes in the central nervous system are more pronounced: complaints of dizziness, tinnitus, drowsiness, pain in the calf muscles. Objectively, changes in the EEG, conditioned and unconditioned reflexes, memory impairment, impaired coordination of movements are detected. There is an increase in energy expenditure and weight loss. More often than under the action of local vibration, vestibular disorders are detected. When combined with noise, vibration leads to hearing loss. This is characterized by a deterioration in the perception of sounds not only high, but also low frequencies. Sometimes visual disorders are detected: a change in color perception, the boundaries of the visual field, a decrease in visual acuity. On the part of the cardiovascular system, there is instability of blood pressure, the predominance of hypertensive phenomena, and sometimes a sharp drop in blood pressure by the end of work. There may be cases of spasm of the coronary vessels, the development of myocardial dystrophy. Lesions of the osteoarticular apparatus are mainly localized in the legs and spine. The action of general vibration can contribute to disorders of the functional state internal organs, the appearance of pain in the stomach, lack of appetite, nausea, frequent urination. Pathological changes in the pelvic organs can be accompanied by impotence in men, menstrual irregularities, prolapse of the pelvic organs, and increased gynecological morbidity in women.

The initial forms of vibration disease are more easily reversed after a temporary cessation of contact with sources of vibration, the introduction of a rational work regime, the use of massage, water procedures, etc. In the later stages of the disease, long-term treatment and complete elimination of the effect of vibration during work are necessary.

Theoretically, it would seem that it does not matter which instrument causes vibration: other things being equal, its parameters play the main role. In principle, this is the case, but this is true only "ceteris paribus." In reality, the nature of the profession determines some features in the course of the disease, for example, any local process develops more acutely. So, as Japanese researchers note, gastric diseases are widespread among truck drivers. It is also known that skidder drivers at logging sites have symptoms of vibration disease accompanied by sciatica. Pilots, especially those working in helicopters, often experience loss of visual acuity. As shown in special studies, single, and short-term - about 20-30 minutes. vibration, increases the time for solving elementary tasks, i.e. impairs attention and mental activity, while up to 30% of decisions are erroneous.

The research revealed a very important biological pattern. It turns out that the weakening of attention is observed only at certain frequencies of the order of 10-12 Hz, while other frequencies, higher and lower, but with the same acceleration, do not cause such changes. This pattern gives the key to clarifying the features of vibration diseases associated with a particular production activity. Each machine or unit generates, along with a mass of side frequencies (harmonics), one main frequency for this machine. This frequency determines the specificity of diseases.

If a vibration with a frequency above 15 Hz (especially with a frequency of 60-90 Hz) affects a person along his torso in the direction of the vertical axis, then visual acuity decreases, the ability to follow the vibrational movements of an object is lost already at frequencies of 1-2 Hz and almost disappears at 4 Hz . This simple example shows how dangerous transport vibration is: drivers, pilots, drivers of other Vehicle no longer distinguish between moving objects.

The frequency of vibration caused by road roughness and the imperfection of land transport lies in the range up to 15 Hz, i.e. represents a real danger and can cause accidents.

Vibration disturbs human speech. At frequencies between 4 and 10 Hz, speech is distorted and sometimes interrupted. To maintain clear and correct speech, special training is needed, since intelligible speech is difficult to maintain at a vibration level of 0.3 dB. It is easy to understand how this affects the communication of pilots and cosmonauts with ground control points.

Pilots, drivers, machinists develop the same signs of vibration disease as workers. Helicopter pilots have a particularly severe disease. In flight, low-frequency vibrations occur, which are poorly damped by the human body and have a destructive effect on the entire body, primarily on the nervous system. Violations of the nervous and cardiovascular activity in pilots occur almost 4 times more often than in representatives of other professions, and vibration plays a significant role here.

The specific sensation that we perceive as sound is the result of the impact on the human hearing apparatus of the oscillatory movement of an elastic medium - most often air. However, not all vibrations of the environment, reaching the ear, cause a sensation of sound. The lower limit of audible sound is oscillations with a frequency of 20 oscillations per second (20 Hz), the upper limit lies between 16,000 and 20,000 Hz. The position of these boundaries is subject to individual changes.

Scope of ultrasound

Outside the specified frequency range, there are also oscillatory processes that do not physically differ from sound vibrations and waves, but are not perceived by the ear as sounds. Fluctuations of the medium with frequencies above the upper limit of hearing, of the order of tens and hundreds of thousands of hertz, are commonly called ultrasounds.

In recent years, ultrasound has found wide application in the national economy, biology and medicine. In the US, for example, there are now millions of ultrasonic units.

Ultrasounds are used in industry, the frequency of which is billions of times higher than the intensity of the audible sounds around us. Ultrasounds can be focused and create very high local pressure. Ultrasound can break up matter and speed up chemical reactions. Ultrasound is able to introduce water into colloids. With the help of ultrasound, the processes of tanning leather, dyeing, bleaching and washing fabrics, obtaining synthetic fibers, leather substitutes and plastics are significantly accelerated. Ultrasound is used for flaw detection, which makes it possible to determine internal defects in parts, for cleaning boilers from scale, underwater surfaces of ships, for aluminum tinning, silvering, etc. Ultrasound has found application in blast-furnace production, in water transport, in fishing and geology.

Ultrasound is used in medicine for diagnostic purposes (identifying foreign bodies), in dentistry (drills), for the manufacture of emulsions medicinal substances etc.

Currently, low-intensity ultrasound is widely used for therapeutic purposes.

Ultrasound has a complex and pronounced biological effect, the essence of which has not yet been sufficiently elucidated. This action, apparently, mainly depends on the huge local pressures created in the tissues and on the local thermal effect associated with the absorption of energy during vibration damping. Liquid media and gases absorb ultrasound, while solids conduct it well. Bones are also good conductors of ultrasound.

The effect of ultrasound on the human body

When exposed to ultrasound on the human body, first of all, a thermal effect is noted due to the conversion of ultrasound energy into heat. Ultrasound causes tissue micro-massage (compression and stretching), which promotes blood circulation and therefore improves tissue function. Ultrasound stimulates metabolic processes and also has a neuroreflex effect.

Under the influence of ultrasound, changes are observed not only in the affected organs, but also in other parts of the body. With prolonged and intense exposure, ultrasound can cause destruction of tissue cells.

The destructive effect of ultrasound is apparently associated with the phenomenon of cavitation - the formation of cavities in the liquid, which leads to tissue death and death of experimental animals.

Microscopic cavitation bubbles were found in the intercellular spaces of animal tissues under the influence of ultrasonic waves of high intensity.

Many microorganisms can be destroyed by ultrasound. So, it inactivates the virus of poliomyelitis, encephalitis, etc. Streptococci after exposure to ultrasound are worse phagocytized. The impact of ultrasonic waves on proteins leads to serious structural disturbances of protein particles and their disintegration. When milk is irradiated with ultrasound, vitamin C is destroyed.

With the so-called sonication of blood by ultrasound, the destruction of erythrocytes and leukocytes occurs, the viscosity and blood coagulation increase, and the ROE is accelerated. Ultrasound inhibits cell respiration, reduces oxygen consumption, and inactivates certain enzymes and hormones.

When exposed to high-intensity ultrasound, animals experience severe pain, alopecia, burns, clouding of the cornea and lens, hemolysis, serious changes in the biochemical nature (decrease in blood cholesterol, uric and lactic acid), at high frequencies death occurs (small hemorrhages in various organs ).

As experimental data and clinical observations show, ultrasound can cause serious changes in the organ of hearing. Ultrasound causes destruction of the cells of Corti's organ and nerve cells, hemorrhages in the scala tympani, destruction and pathological development of bone tissue. It is believed that the hearing changes identified in a large percentage of the US population are associated with a significant spread of sound installations.

In persons who have been exposed to ultrasonic vibrations for a long time, drowsiness, dizziness, and rapid fatigue are noted. The examination reveals the phenomena of vegetative dystonia.

The use of ultrasound in medicine

The therapeutic effect of ultrasound is mainly due to its ability to penetrate tissues and cause their heating and micromassage. Nevertheless, it should be noted that ultrasound, obviously, has some specific features of action, since deep heating of tissues can be obtained using other methods, and a positive effect sometimes occurs only after the use of ultrasound.

Given the reflex mechanism of ultrasound, it can be used not only for direct impact on the pain focus, but also for indirect effects.

Due to the above properties, ultrasound under certain conditions can have an analgesic, antispasmodic, anti-inflammatory and bactericidal effect. The use of ultrasound can be combined with other types of therapy.

Due to the high biological activity of ultrasound during treatment, great care must be taken. Positive results in the therapeutic use of ultrasound have been obtained in many diseases. The use of ultrasound is effective in the treatment of myalgia, neuralgia, neuritis of amputation stumps, arthrosis, arthritis and periarthritis. An indicator of the general effect of ultrasound on the body is, in particular, the fact that when many joints are affected, it is often enough to confine oneself to the treatment of one of them, since a parallel improvement is observed in other joints. Good results were obtained in the treatment of ankylosing spondylitis, spondylitis, trophic and varicose ulcers, obliterating endarteritis, sluggishly granulating ulcers with ultrasound.

There are separate indications of the positive use of ultrasound in gastric and duodenal ulcers, bronchial asthma, emphysema, bronchiectasis, otosclerosis, Meniere's disease. There are observations indicating that preliminary sonication of human skin increases the effectiveness of X-ray irradiation.

Contraindications to the use of ultrasound

Of course, it is contraindicated to sound the growing bones, genitals, heart area (which can cause angina pectoris), tumors. With pulmonary tuberculosis, hypertension, hyperthyroidism, pregnancy, changes in parenchymal organs, the use of ultrasound is also contraindicated.

The ever-increasing use of ultrasound makes it necessary to organize careful monitoring of persons who have contact with him, in order to identify early signs of the disease and timely conduct the necessary therapeutic and preventive measures.

There are indications of the beneficial effects of ultrasound in certain forms of cancer and neuritis. However, it has not yet been established exactly how wide the safe zone is between the positive effect of ultrasound on the diseased tissue and the damaging effect on the surrounding healthy tissue.

Ultrasounds ( inaudible sounds) are mechanical vibrations of an elastic medium and differ from sound waves by a higher frequency exceeding the upper threshold of audibility (20,000 Hz); the range of ultrasonic vibrations is extremely wide - from 2 104 to 109 Hz (Table 32).

Ultrasonic waves propagate in any elastic medium (liquid, solid, gaseous), better in metals, water, worse in air.

The relationship between wavelength (λ), frequency (f) and speed (c) is expressed by the formula:
λ=c/f
When it hits the boundary of two different media, part of the energy passes into another medium, part is reflected. The greater the acoustic resistance of the media (the product of the density of the medium and the speed of propagation of ultrasound in it), the less the transition of ultrasounds from one medium to another. For example, almost 10% of ultrasonic energy is transferred from iron to water and only 0.1% is transferred from iron to air. The greatest reflection of ultrasonic vibrations is observed at the water-air interface; ultrasound passes well from water to biological tissues. When passing through various media, ultrasonic waves are absorbed to varying degrees by them, which is the reason for the selective action. For example, the absorption properties of muscle tissue are higher than fat; in the gray matter of the brain, absorption is almost 2 times higher than in the white; the greatest absorption is observed in the bone tissue, the smallest - in the cerebrospinal fluid.

The absorption of ultrasound is accompanied by heating of the medium. The thermal effect is enhanced with an increase in the oscillation frequency. In addition to the thermal effect, ultrasound causes a number of other phenomena in media. For example, the passage of ultrasound in a liquid is accompanied by the effect of cavitation. When elastic waves propagate in a liquid, the phases of compression and rarefaction arise in succession, in some areas gaps or cavities are formed, which are filled with vapors of the liquid and gases dissolved in it. In this case, a large pressure is created in the formed bubble, which can reach several atmospheres. Subsequent compression leads to the collapse of the bubble, which is accompanied by a hydraulic shock, which has a large destructive force. This is due to the mechanical action of ultrasound. The formation of cavitation cavities is accompanied by the propagation of electric charges on the boundary surfaces, causing a luminescent glow and ionization of water molecules. A number of chemical effects are associated with these phenomena: the oxidizing effect of ultrasound, the acceleration of chemical reactions, and the destruction of organic compounds.

Ultrasounds were first used by the Frenchman Langevin and the Russian engineer N.K. Shilovsky in 1916 for the purpose of sonar. The beginning of the industrial application of ultrasounds was laid by the Soviet scientist S. Ya. Sokolov, who in 1927 developed the world's first ultrasonic flaw detector. Currently, ultrasounds are used in mechanical engineering, metallurgy, radio engineering, chemical, pharmaceutical, light and other industries.

In technology, ultrasound is used to intensify technological processes - when cleaning and degreasing parts, machining hard and brittle materials (drilling, cutting), welding, soldering, tinning; to accelerate chemical reactions in electroplating, when receiving emulsions; washing glass containers, for analysis and control (defectoscopy, determination of viscosity, density, temperature of the materials under study, etc.).

Acoustic transducers are used as sources of ultrasound: piezoelectric, magnetostrictive, aerodynamic, hydrodynamic (whistles, sirens), electrodynamic. The most common in industry are piezoelectric and magnetostrictive transducers. Piezoelectric transducers are mainly used in instrumentation and flaw detectors. For these purposes, high-frequency ultrasounds (of the order of several megahertz), but of low power (100-300 watts) are more often used. Magnetostrictive transducers are more widely used in industry. They are used to generate ultrasound during the intensification of technological processes. For technological purposes, low-frequency ultrasounds of 24,000-30,000 Hz are used. The power of the converters used, depending on the technological process, is different and ranges from 100 watts to 5-10 kW. It is this area of ​​application of ultrasound that should first of all attract the attention of a doctor.

The main elements of ultrasonic equipment are a generator and an acoustic transducer. Under the influence of a variable electric current supplied from the generator, mechanical vibrations are excited in the converter.

In processes that take place in a liquid (cleaning and degreasing of parts, electrical processes in electroplating), the plate converter is built into the bottom of the bath. From the radiating surface ere, vibrations are transmitted to the liquid into which the workpieces are immersed. The processes associated with the excitation of ultrasound in solid media (drilling, welding, cutting, etc.) are carried out on machine tools, machines and units. The rod transducers built into them are fastened to a tool (drill, cutter), through which ultrasonic vibrations act on the workpiece.

The operation of ultrasonic equipment, regardless of whether the process proceeds in a liquid or solid medium, is accompanied by the propagation of ultrasonic vibrations in the environment. The source of ultrasound is the open surface of the transducer. During processes carried out in a liquid, ultrasound also enters the air from its surface. But in isolation, ultrasonic vibrations almost never occur in production conditions. The generation of ultrasonic vibrations is accompanied by audible noise, which is caused by cavitation, vibrations of workpieces and metal structures of equipment.

The impact of sound and ultrasonic vibrations on the body of workers occurs through the air and due to direct contact of the hands of the worker with the media in which vibrations are excited (contact path of exposure).

In industrial premises, the total levels of sound and ultrasonic pressure at different technological processes range from 90 to 130 dB. The spectrum of vibrations created by ultrasonic equipment in the air is characterized by an extraordinary breadth. It covers the entire audible frequency range and continues into the ultrasonic region. When the operating frequency of the equipment is 20,000 Hz, ultrasounds with a frequency of up to 100,000 Hz are observed in the spectrum. However, the most high levels fall on the region of high sound and low ultrasonic frequencies, i.e. from 8000-10000 to 31000 Hz with a maximum at the operating frequency. A peculiar complex of high-frequency sound and low-frequency ultrasonic vibrations is a feature of working conditions. In the case of using ultrasonic vibrations in a liquid, an increase in spectral levels can be observed from 4000-6000 Hz. An increase in the operating frequency accordingly causes changes in the spectral composition: the bulk of the energy is located in the region of the operating and nearby frequencies (Fig. 35).

Rice. 35. Spectrum of vibrations created by ultrasonic baths for cleaning parts.

1 - at an operating frequency of 20 kHz; 2 - at an operating frequency of 40 kHz.

The contact effect of ultrasound is local, as a rule, periodic and short-term. The hands of the worker are exposed to the impact, more often during the loading and unloading of parts during the maintenance of ultrasonic baths, while holding the part with their hands during processing, during soldering and tinning, and sometimes during welding and cleaning. Sometimes such contact is the result of non-compliance with safety precautions by workers. Given that in the environments with which the workers come into contact, the intensity is quite high, even short-term contact is highly undesirable.

Of the methods of ultrasonic analysis and control, flaw detection has the widest application. In flaw detection, as a rule, high-frequency ultrasounds of the order of hundreds of kilohertz and several megahertz are used. In this case, the main attention should be paid to the prevention of contact impact, especially during the installation, adjustment and testing of flaw detectors. Studies of the state of health of those working with flaw detectors, according to foreign authors, did not reveal any noticeable signs of exposure to ultrasound.

During the operation of sirens, whistles, Sinclair electrodynamic emitters, ultrasonic fields with an intensity of 140-160 dB can be created in the air. These types of equipment are used for experimental work, and are almost never found in production conditions.

The most studied biological effect of ultrasound is its contact action. The experiment found that ultrasonic vibrations, penetrating deeply into the body, can cause serious local disorders in tissues: an inflammatory reaction, hemorrhages, and at high intensity - necrosis.

Under production conditions, due to short-term exposure to ultrasound, the above-described gross violations of contact are not observed. With systematic contact with a source of ultrasound in a liquid (in medical workers), occupational diseases were revealed - paresis of the hands and forearms. There are experimental data on the effect of ultrasound propagating in air. Low-frequency high-intensity ultrasounds (160-165 dB) within a few minutes cause the death of animals from paralysis of the respiratory center with skin burns, hyperthermia, paralysis of the limbs.

The results of clinical observations of the state of health of workers were obtained under conditions of simultaneous action of noise and ultrasound. Persons serving ultrasonic equipment present a variety of complaints, mainly headache, dizziness, fatigue, sleep disturbance, daytime sleepiness, irritability, increased sensitivity to sounds. By the end of the shift, there may be an increase in body temperature, a decrease in heart rate, a slowdown in reflex reactions to external stimuli. Clinical examination revealed asthenic syndrome.

Studies of higher nervous activity indicate a decrease in the activity of inhibition, the strength of the excitatory process, and its inertia. Individuals who have been engaged in experimental work on ultrasonic devices for a long time sometimes experience diencephalic disorders (weight loss, a sharp rise in blood sugar with a slow fall to the initial level, hyperthyroidism, increased mechanical excitability of muscles, itching, paroxysmal attacks such as visceral crises). There are frequent violations of the function of the peripheral nervous system, numbness, a decrease in all types of sensitivity by the type of short and long gloves, hyperhidrosis. Hearing loss and peculiar disorders of the vestibular apparatus are also observed - the absence of nystagmus in one or both directions during vestibular tests, dissociation between nystagmus and other reflex reactions, dissociation between rotational: and caloric test. The changes are the result of the combined action of noise and ultrasound. Peripheral disturbances are mainly due to the contact effect of ultrasonic vibrations. Measures should be aimed at limiting the impact of sound and ultrasonic vibrations transmitted through the air and by contact.

The main measure to reduce noise and ultrasound is to reduce their intensity at the source, but this way is not always technically possible. At industrial enterprises, an overestimated intensity of ultrasonic vibrations is often used, therefore, first of all, attention should be paid to the rational selection of equipment power. In cases where reducing the intensity is contrary to the interests of technology, the most effective measure to reduce noise and ultrasound is soundproofing the equipment.

Our country already has experience in the use of soundproofing devices. Bathtubs in soundproof execution are serially produced. Soundproofing is provided by a casing made of sheet steel with a hermetically sealed lid. The inner walls of the casing are lined with a layer of porous rubber. The total level of sound and ultrasonic pressure is reduced by 25-30 dB.

It should be borne in mind that at the time of loading and unloading parts, the sound insulation is broken. Therefore, it is advisable to provide automatic shutdown of vibrations when opening the cover of the casing. It is also desirable to use soundproofing devices for powerful machine tools and welding machines.

The use of a soundproof casing on machine tools makes it possible to reduce the level of sound and ultrasonic pressure by 30-40 dB. Since the casing completely covers the work surface, its use creates inconvenience during short-term processing, which requires frequent changes in the workpieces, but can be successfully used for a long process.

Prevention of contact exposure to ultrasound is achieved by turning off oscillations during the loading and unloading of parts, for which it is recommended to use auto-blocking.

To a large extent, it is possible to weaken the intensity of the contact effect by using special devices for loading parts (grids, plexiglass vessels, etc. with handles having an elastic coating). If necessary, periodic short-term contact is recommended to use clamps, tongs, wearing rubber and cotton gloves. On the walls and welding machines, special devices must be provided for fixing parts during processing.

Methodological guidelines for industrial sanitary doctors and medical units on the prevention of the harmful effects of ultrasound when used in industry No. 424-63 (approved on January 31, 1963 by the USSR Ministry of Health) provides for systematic monitoring of the health of workers by conducting preliminary examinations in case employment and periodic medical examinations of employees once a year.

Ultrasonic repellers have recently received wide practical application. They are very often used to fight various rodents, insects, stray animals. It turns out that the ultrasonic wave can cause discomfort, pain, panic and fear.

Ultrasonic rodent repeller

But at the same time, the natural question is whether the ultrasonic rodent repeller is harmful to humans. Consider what ultrasound is and how it affects the human and animal body. This will allow you to make the right decision for yourself whether or not to use ultrasonic repellers at home.

To figure out whether an ultrasonic repeller is dangerous for people, consider what an ultrasonic wave is. Ultrasound belongs to the category of sound waves, which are vibrations of the molecules of the medium in which they propagate. Through these waves, sound information is transmitted to the auditory organs.

A feature of ultrasonic waves is their high frequency and short wavelength. As a result, they have a high penetrating power.

The frequency interval occupied by ultrasonic waves is from 20 to 70 kHz. This range is "inaudible to humans" because their ear can perceive sound waves in the range from 10 Hz to 16 kHz.

In what areas is ultrasound still used?

In addition to ultrasonic repellers, ultrasound has a wide practical application in various branches of human activity.

Among the main ones are the following:

• diagnostic procedures in medicine;
• echolocation;
• use for flaw detection;
• implementation of therapeutic methods in the treatment;
• use in production processes;
• application for the preparation of various mixtures;
• use for ultrasonic welding;
• application in electroplating;
• for various scientific research.

To conclude whether ultrasonic repellers are harmful to humans, consider the impact of ultrasound on human and animal health. As described above, a person cannot hear ultrasonic waves, since his hearing aid is designed for a completely different range - 10 Hz ... 16 kHz. As a result, a person will not feel any irritability or discomfort when he is near a working repeller.

When characterizing sound waves, it is important to remember not only the frequency, but also the pressure that the sound creates. Modern ultrasonic repellers generate ultrasonic waves, the pressure of which is in the range of 72 ... 100 dB.

This level of pressure is safe for a person whose hearing aid normally perceives waves with sound pressure up to 100 dB. At great importance pressure, pain may occur. Therefore, the ultrasonic mouse repeller will not have an effect on humans.

But with rodents and some animals, things are quite different. Their hearing aid is just able to perceive ultrasonic waves. Therefore, they may seem like a noise irritant to them.

But, this is only half the trouble - it turns out that sound pressure, which does not cause harm to humans, adversely affects rodents. Their hearing aid is so sensitive that an ultrasound wave of 70 dB or more will cause painful sensations in rodents.

As a result of such exposure, rodents will feel pain, fear, discomfort and anxiety when they enter the area of ​​​​impact of the device. These factors lead to the fact that rodents try to leave the occupied territories as quickly as possible.

As for pets, ultrasound does not affect them, as well as people. The only exceptions are those animals that belong to a number of rodents - Guinea pigs, hamsters, tame rats, etc. True, this does not mean that any repeller can be installed in the premises where pets are located.

There are models that use in the course of their work not only ultrasonic waves, but also ordinary sound waves. Such devices will cause discomfort for both pets and humans. Therefore, ultrasonic devices can only be used in strict accordance with the instructions and recommendations of the manufacturer.

Conclusion

Having studied how the ultrasonic repeller acts on the human body and on rodents, we can conclude that these devices are completely safe and cannot harm health. For this to be so, it is important to choose the right repeller.

Today, there are models that can be used in residential areas, and there are devices that are designed for objects where there are no people. Therefore, the choice of repeller is important point that it won't harm a person.

To diagnose the state of health, specialists perform an ultrasound examination on patients. This method has been practiced for 30 years. Currently, ultrasound is the main method for examining human organs without surgical intervention. Is ultrasound harmful to humans, and why is it dangerous?

Characteristic

Ultrasound is mechanical vibrations with a frequency of more than 16-20 kHz, which are not picked up by hearing. It is used in the following industries:

1. in industry and agriculture: cutting, welding, surface cleaning and more.
2. In medicine: detection of many diseases.
3. In cosmetology: skin cleansing.
4. It is used in the operation of large industrial machines: turbines, jet engines.

In general, in a production environment, the frequency of ultrasound is in the range of 20 - 70 kHz.

Ultrasound affects the health of medical workers when their hands come into contact with fluid and instruments. Many researchers believe that such frequencies can also negatively affect people through the air.

Symptoms of negative influence

With prolonged action of ultrasonic frequencies on a person, his nervous system suffers. Workers servicing such equipment may experience headaches, insomnia, irritability, and memory problems. Also, in some people, hearing may deteriorate, the complexion may change: turn pale or blush.

When conducting diagnostic examinations, there are cases of manifestation of asthenovegetative or asthenic syndrome. You can also find a negative impact in the form of hallucinations, weight loss, visceral crises. Rarely there are malfunctions in the function of the thyroid and sex glands.

The harm of ultrasound is also manifested by a decrease in the quality of perception of low or high sounds. Prolonged exposure may cause polyneuritis. Sometimes the sensitivity of any parts of the limbs decreases. The loss of useful elements in the body is extremely rare. However, all these symptoms are mostly unstable.

Such manifestations of negative impact occur when a person needs frequent ultrasound diagnostics to study their health status. The harm of ultrasound for the patient will be minimal if you resort to it 2-3 times a year, while there should be significant pauses between sessions. Symptoms of the disorder appear in professionals who regularly use this equipment or in the event of a security breach.

There are 3 stages of the negative impact of ultrasound:

• Initial - there are disorders of the nervous system, vegetative polyneuritis, endocrine changes in a weak degree.
• Moderately pronounced - increased symptoms of the first stage, as well as mild diencephalic disorders.
• Severe - diencephalic crises, disorders of the central nervous system in a weak degree.

Treatment

With the manifestation of mild signs of asthenic syndrome and vegetative-vascular disorders, a person remains able-bodied. However, it is necessary to monitor his condition and carry out treatment. A visit to a dispensary or sanatorium is recommended.

In more complex cases, you should be transferred for 1-2 months to work that does not involve the use of ultrasound. If strong neurodynamic and neurocirculatory changes are detected, problems with hearing and the vestibular apparatus appear, it is necessary, in addition to appropriate treatment, to change the place of work.

ultrasound during pregnancy

An ultrasound examination during gestation is a standard procedure that must be performed at least three times in all 9 months. Is ultrasound dangerous during pregnancy? Recently, many women refuse such a study, as it is widely believed that ultrasound is extremely harmful to the fetus in the womb.

Large-scale studies on this subject have not been carried out, but some scientists talk about harm. Doctors, on the other hand, argue that there are too few scientific studies to speak with confidence about the benefits and harms of ultrasound.

In this regard, one should not often resort to this diagnostic method without special need. The ultrasonic frequency definitely affects the child, it can even affect the formation of his organs. P. Garyaev's research suggests that there is a possibility of gene mutation in the fetus.

Gynecologists consider ultrasound the most convenient and safe method of examination. It is carried out for the purpose of:

1. Pregnancy confirmation.
2. Identification of gestational age.
3. Exceptions for abnormal development of the embryo.
4. Determination of the sex of the child.
5. Confirmation of fetal viability.
6. Finding out the location of the placenta at the moment.
7. Identification of the biophysical state of the baby.

In pregnancy, ultrasound is an important method to ensure a good check of fetal development. The procedure allows you to save the health of the mother and her baby.

Ultrasound Safety

Doctors argue the absence of harm from ultrasound during pregnancy with the following facts:

• The examination excludes any radioactive radiation.
• The energy from the equipment is very weak, so this frequency cannot be dangerous for the baby's delicate tissues and organs.
• An ultrasound examination is more beneficial than harmful, since such a procedure allows you to quickly detect any abnormalities in the development of the fetus.

Harm of ultrasound

Is ultrasound harmful to humans? This diagnostic method is not irradiating, since it differs from the principle of operation, in which some dose of radiation enters the body. Ultrasound is just a number of sound vibrations. Waves cannot accumulate in the body.

Therefore, we cannot speak of poisoning here. Negative influence on a person can only be with regular contact with this diagnostic tool. When it is turned off, the negative impact stops. For its safe use, the recommended examination schedule must be followed.

Doctors say that the planned ultrasound during pregnancy is not dangerous for the baby. It can also be used to examine young children or teenagers. It can also be said about other medical and cosmetic procedures where high-frequency sound is used.

Video: is ultrasound harmful to humans?

Prevention

To minimize the harmful effects of ultrasound, the following recommendations should be followed:

1. Ultrasonic equipment is best installed in isolated rooms.
2. It is necessary to limit as much as possible the contact of hands with liquid in ultrasonic baths and with the instrument during the passage of frequency oscillations through it.
3. Loading and unloading of tools must be carried out with the equipment turned off.
4. When working on machine tools, tool elements must be fixed with the help of certain devices.
5. The worker should wear double gloves: first cotton, and rubber on top.

Is ultrasound really harmful? The negative impact after applying this diagnostic method in medicine has not been proven by scientists, so it is impossible to give an exact answer to this question. It is currently the most safe method study of the internal organs of man.

Professionals who have to work regularly with ultrasonic equipment should follow the safety rules. Otherwise, various disorders may occur. Basically, such problems are faced by people serving powerful production or traction equipment. But technology developers take this into account and strive to minimize the danger posed by their tools.