Question related to ultrasound, what is ultrasound

Bats with echolocation capabilities produce short, high-frequency sound pulses that reflect off nearby objects.

Human tissues have a relatively large ability to absorb ultrasound energy, so when ultrasound waves propagate in human tissues, its energy is continuously absorbed by tissues and turned into heat, and the result is that the temperature of the tissue's own body rises.

The process of heat production is both mechanical energy.

The process of energy conversion into heat energy in a medium. i.e. endogenous heat. The ultrasonic warming effect increases blood circulation.

Accelerate metabolism, improve local tissue nutrition, and enhance enzyme activity. In general, the thermal action of ultrasound takes place on bone and connective tissue.

For significant, fat and blood are minimal.

The magnitude of loudness is mainly dependent on the intensity of the sound and is related to the amplitude and frequency of the sound. The subjective perception of strength is called loudness.

No matter how high the sound level is, it cannot be heard by the human ear. Therefore, the hearing frequency of the human ear is 20Hz 20kHz, and this frequency band is called audio or sound frequency; Regardless of the sound pressure, the human ear is most sensitive to sound at the frequency of 3kHz and 5kHz. Therefore, ultrasound is not felt and cannot be heard.

There is no loudness, let alone deafening. Regardless of the sound pressure, the human ear is most sensitive to sound at the frequency of 3kHz and 5kHz.

Infrasound waves are very harmful to people. For example, infrasonic waves** resonate with human tissues, and sound wave energy acts on the human body due to resonance. Hurt the most.

Ultrasonic frequencies are also destructive to the human body when the frequency is particularly high, such as 433 MHz, 915 MHz, 2450 MHz, 5800 MHz, 22125 MHz for industrial, scientific and medical use, which are used separately from the communication frequency. At present, the common frequencies used for industrial heating in China are 915 MHz and 2450 MHz. High frequencies produce a thermal resistance effect.

At this time, ultrasonic waves cause molecules to collide and rub against each other to generate heat energy, resulting in the heating of food. If a person is at this frequency, when the (energy) sound is very strong, it is familiarized, and it will definitely not be heard.

Loudness is determined by human hearing, and if it is an inaudible ultrasound, its loudness is 0 or close to 0

Ultrasound waves that are too loud will not affect the hearing from the angle of "too loud", but ultrasound waves will damage the cells of the human body, causing the cells to burst, and this damage will not only affect the hearing cells, but also other cells.

Ultrasound is inaudible to the human ear. The situation you are talking about will not deafen the human ear. But if there's an animal next to her, she's miserable. Rest assured, believe it or not, that's the way it is.

If the human ear is deaf, the sound wave should be heard with a relatively large amplitude and relatively close to the natural frequency of the human eardrum, and if it is ultrasound, the human eardrum will hardly vibrate. It must not be heard.

I think that the natural frequency of the eardrum is also a factor in why the human ear can hear sound waves in a certain wavelength band.

There is a report in the laboratory file, 130 150 decibel ultrasound, the impact of this sound wave can cause seven holes to bleed to death? Generally, bats are immune to ultrasound waves of 300 400 decibels, and the ultrasonic waves emitted by the bats themselves are in the range of 800 900 decibels, but in fact, if they exceed 100 decibels, the human ear cannot bear them.

Sonic waves, ultrasonic waves, are all mechanical waves.

The frequency range of sound waves that can be heard by the human ear is 20Hz to 20kHz.

Compared to sound waves, the frequency of ultrasound waves is higher than 20kHz.

Because the frequency of ultrasound exceeds the upper limit of the frequency of the human hearing domain, it is called ultrasound.

In addition, mechanical waves with a frequency of less than 20 Hz are called infrasound.

The human ear cannot hear ultrasound waves, nor can infrasound waves.

Ultrasound can weld metals. Common metal ultrasonic welding can be divided into spot welding, girth welding, seam welding and wire welding.

1. Spot welding. According to the vibration condition of the upper sound rod, the vibration system of the spot welding machine can be divided into longitudinal vibration (light structure) system, bending vibration (heavy structure) system and light bending vibration system, the light structure is suitable for small spot welding machines with power less than 500W, the heavy structure is suitable for kilowatt high-power welding machines, and the light bending vibration system is suitable for medium and small power welding machines, both of which have the advantages of two vibration systems.

2. Ring welding. With the ring welding method, a closed weld can be formed in one pass, and a torsional vibration system is employed. During the welding process, the vibration amplitude is symmetrical and linear relative to the acoustic rod axis, the amplitude in the axial region is zero, and the amplitude of the pad edge is the largest.

Obviously, circumference welding is most suitable for the packaging process of microelectronic devices.

3. Line welding. Wire welding can be seen as an extension of the spot welding method. In this method, a 150 mm long linear weld is obtained through a linear upper acoustic pole. This method is suitable for the wire sealing of foils.

4. Seam welding. The vibration system of the seam welding machine can be divided into according to the vibration state of its pad;

a-Longitudinal vibration system;

b- Bending vibration system;

c-Torsional vibration system and other categories.

Among them, A and B are more commonly used. The direction of vibration of its pads is perpendicular to the direction of welding. The direction of vibration of C is parallel to the direction of welding.

Seam welding can obtain a sealed continuous weld. Usually the workpiece is clamped between the upper and lower pads. In special cases, a flat plate lower sound pole can be used.

The sound frequency that can be heard by the human ear is 20-20000Hz, and the sound below 20 is called infrasound, and above 20000 is ultrasound.

It is the sound that exceeded the speed of the sound.

Ultrasound waves can be generated by the vibration of harder crystal materials. Due to the high frequency and short wavelength of ultrasound, it travels in a straight line approximately, can form a beam, and the energy is easy to concentrate, so it can form a great intensity. Some places that cannot be observed with light can sometimes be detected by ultrasound.

For example, the density and elasticity of different objects are different, and the reflection or absorption of ultrasonic waves is also different, so the echo of ultrasonic waves can be used to detect cracks in metals, tissues inside the human body, or fetuses in the mother's body. Ultrasound can be used for medical examination. For example, observing the growth of the fetus and examining the internal tissues and organs of the human body.

Ultrasound can evenly mix liquids that cannot be mixed evenly, and this method is commonly used in medicine to create drugs that can be absorbed by humans. Ultrasonic can also be used to clean delicate parts with complex shapes, porous and messy. With the development of science and technology, the application of ultrasound will be more extensive.

Ultrasound is an important branch or component of acoustics. It mainly focuses on the study of the generation, propagation, reception and interaction of ultrasound with various substances in various substances, as well as various effects and applications.

Sound waves belong to mechanical waves, which are the propagation of mechanical vibrations in an elastic medium. Modern acoustics has covered a wide frequency range from 10 4 1014 Hz, which corresponds to infrasound vibrating every 3 hours to molecular thermal vibrations with wavelengths shorter than the spacing between atoms in solids, i.e. spanning a wide frequency band of the order of 1018.

Ultrasonic propagation generally has a certain power range, and the power range is different depending on the propagation mode. Continuous-wave ultrasound is generally in the range of milliwatts to tens of kilowatts. Pulsed wave ultrasound can be scaled up to a fraction of a milliwatt to a few megawatts.

Correspondingly, from the perspective of sound intensity, the upper limit of focused continuous wave ultrasound in liquids can reach tens of kilowatts per square centimeter due to the limitation of cavitation; Focused pulsed ultrasound can reach tens of megawatts per square centimeter in the center of the focal spot.

Due to the larger power range and stronger sound intensity of pulsed wave ultrasound, modern ultrasound applications such as ultrasonic cleaning and ultrasonic cell crushing mostly use pulsed wave ultrasound.

The description of ultrasound is as follows:

1.As it flies, it makes a sound from its mouth. This sound is called ultrasound, and it is inaudible to people's ears, but it can be heard by the ears of bats.

The ultrasound waves move forward like waves, and when they encounter obstacles, they radiate back and reach the bat's ears, which immediately change the direction of flight.

2.Ultrasound is a sound that humans cannot hear.

3.At night, bats make a thin sound called ultrasound while flying. The ultrasound hit an obstacle and was about to return, but the bat heard it and changed direction.

What is Ultrasound:

Ultrasound is a very short wavelength of mechanical waves, generally shorter than 2 cm (centimeter) in air. It must rely on a medium for propagation and cannot exist in a vacuum, such as space. It travels farther in water than in the air, but because of its short wavelength, it is very easy to lose and scatter in the air, and it is not as long as audible sound and infrasound waves, but the short wavelength is easier to obtain anisotropic sound energy, which can be used for cleaning, gravel, sterilization and disinfection.

There are many applications in medicine and industry.

Ultrasonic is a kind of mechanical wave, which must rely on the medium to propagate, and cannot exist in a vacuum (such as space), so we cannot use ultrasonic waves in a vacuum, but we can still use electromagnetic wave-related equipment (including radio waves, microwaves, infrared, visible light, ultraviolet rays, X-rays, gamma rays, etc.) to use electromagnetic wave technology.