The principle of echolocation. Chatty world of silence

ECHOLOCATION ECHOLOCATION

in animals (from Greek echo - sound, echo and Latin locatio - placement), radiation and perception of reflected, usually high-frequency sound signals in order to detect objects (prey, obstacles, etc.) in space, as well as obtain information about their properties and sizes. E. is one of the methods of animal orientation and biocommunication. E. is developed in bats, dolphins, and in certain birds and shrews. In bats, ultrasound is generated in the larynx by special supraglottic cords (possibly vocal cords too) and then directed through the open mouth or nostrils into the environment. Ultrasonic impulses are perceived by the auditory system, which has a number of morphological edges. features. E. is effective in them at a distance of up to 18 m. In dolphins, sounds are probably produced by vibration of the septa or folds of the nasal sacs (according to another version, in the larynx). Dolphins and bats generate ultrasonic pulses with a frequency of up to 150-200 kHz, the duration of the signals is usually from 0.2 to 4-5 ms. Birds living in caves (guajaros, swiftlets) use E. to navigate in the dark; they emit low frequency signals at 4-7 kHz. In dolphins and bats, in addition to general orientation, E. serves to define spaces. target position, including prey, physiol. the system (analyzer) of the animal that provides E. was received in biol. literary name sonar, or sonar (English sonar - an abbreviation of the words “sound navigation and randing” - “sound guidance and determination of distance” - this was the name of the echolocator used to detect underwater objects

.(Source: Biological encyclopedic dictionary." Ch. ed. M. S. Gilyarov; Editorial team: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected. - M.: Sov. Encyclopedia, 1986.)

echolocation

A special method of bioorientation and biocommunication of animals (moths, bats, birds, toothed whales, pinnipeds). Echolocation allows you to make complex movements in poor visibility or complete darkness. Animals generate sound impulses (birds from 4 to 7 kHz, and dolphins up to 200 kHz), perceive reflections (echoes) from surrounding objects with their hearing organs. With the help of echolocation, animals hunt (bats, birds, etc.), communicate (dolphins), and protect themselves from attack (moths of the bear family have an ultrasonic noise generator for bats).

.(Source: “Biology. Modern illustrated encyclopedia.” Chief editor A. P. Gorkin; M.: Rosman, 2006.)

Synonyms:

See what “ECHOLOCATION” is in other dictionaries:

Echolocation... Spelling dictionary-reference book

- (echo and Latin locatio “position”) the method by which the position of an object is determined by the delay time of the return of the reflected wave. If the waves are sound, then this is sonic location, if radio is radiolocation.... ... Wikipedia

Echo sounding, location Dictionary of Russian synonyms. echolocation noun, number of synonyms: 2 location (3) ... Dictionary of synonyms

Echolocation- in animals, see Bioecholocation. Ecological encyclopedic dictionary. Chisinau: Main editorial office of Moldavian Soviet encyclopedia. I.I. Dedu. 1989. Echolocation (from echo and lat. locatio placement) the ability of some... Ecological dictionary

ECHOLOCATION, animals have the ability to navigate by sound. It is best expressed in bats and whales. Animals emit a series of short, high-frequency sounds and, by the reflection of the echo, judge the presence of obstacles around them. Bats and... Scientific and technical encyclopedic dictionary

echolocation- A method of measuring the depth of a sea or lake, in the past using a line lowered on a cable, now using an echo sounder. Syn.: probing... Dictionary of Geography

I Echolocation (from echo and lat. locatio placement) in animals, radiation and perception of reflected, usually high-frequency, sound signals in order to detect objects in space, as well as obtain information about the properties and... ... Great Soviet Encyclopedia

G. Orientation in space using reflected ultrasound. Ephraim's explanatory dictionary. T. F. Efremova. 2000... Modern explanatory dictionary Russian language Efremova

echolocation- echolocation, and... Russian spelling dictionary

echolocation- echolocation/tion, and... Together. Separately. Hyphenated.

Books

• Entertaining wave research. Unrest and hesitation around us, Praetor-Pinney Gavin. G. Pretor-Pinney interestingly and easily introduces everyone to the theory of waves, as well as the importance of waves in our everyday life. waiting for you trip around the world By…

Story

The discovery of echolocation is associated with the name of the Italian naturalist Lazzaro Spallanzani. He noticed that bats fly freely in a completely dark room (where even owls find themselves helpless), without touching objects. In his experiment, he blinded several animals, but even after that they flew on a par with sighted ones. Spallanzani's colleague J. Zhurin conducted another experiment in which he covered the ears of bats with wax - and the animals bumped into all the objects. From this, scientists concluded that bats navigate by hearing. However, this idea was ridiculed by contemporaries, since nothing more could be said - short ultrasonic signals at that time were still impossible to record.

The idea of ​​active sound location in bats was first proposed in 1912 by H. Maxim. He proposed that bats produce low-frequency echolocation signals by flapping their wings at a frequency of 15 Hz.

Ultrasound was discovered in 1920 by the Englishman H. Hartridge, who reproduced Spallanzani’s experiments. Confirmation of this was found in 1938 thanks to bioacoustician D. Griffin and physicist G. Pierce. Griffin suggested the name echolocation(similar to radar) to name the method of orienting bats using ultrasound.

Echolocation in animals

The origin of echolocation in animals remains unclear; it probably arose as a substitute for vision among those who live in the darkness of caves or the depths of the ocean. Instead of a light wave, sound began to be used for location.

This method of orientation in space allows animals to detect objects, recognize them and even hunt in conditions of complete absence of light, in caves and at considerable depth.

Among arthropods, echolocation has been found only in nocturnal moths.

Technical support for echolocation

Sound surveillance equipment from the First World War

Echolocation can be based on the reflection of signals of various frequencies - radio waves, ultrasound and sound. The first echolocation systems sent a signal to a certain point in space and, based on the response delay, determined its distance, given the known speed of movement of a given signal in a given environment and the ability of the obstacle to which the distance was measured to reflect this type of signal. Inspecting a section of the bottom in this way using sound took considerable time.

Nowadays, various technical solutions are used with the simultaneous use of signals of different frequencies, which can significantly speed up the echolocation process.

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Synonyms:

See what “Echolocation” is in other dictionaries:

Echolocation... Spelling dictionary-reference book

In animals (from the Greek echo sound, echo and Latin locatio placement), radiation and perception of reflected, usually high-frequency sound signals in order to detect objects (prey, obstacles, etc.) in space, as well as receive... ... Biological encyclopedic dictionary

Echo sounding, location Dictionary of Russian synonyms. echolocation noun, number of synonyms: 2 location (3) ... Dictionary of synonyms

Echolocation- in animals, see Bioecholocation. Ecological encyclopedic dictionary. Chisinau: Main editorial office of the Moldavian Soviet Encyclopedia. I.I. Dedu. 1989. Echolocation (from echo and lat. locatio placement) the ability of some... Ecological dictionary

ECHOLOCATION, animals have the ability to navigate by sound. It is best expressed in bats and whales. Animals emit a series of short, high-frequency sounds and, by the reflection of the echo, judge the presence of obstacles around them. Bats and... Scientific and technical encyclopedic dictionary

echolocation- A method of measuring the depth of a sea or lake, in the past using a line lowered on a cable, now using an echo sounder. Syn.: probing... Dictionary of Geography

I Echolocation (from echo and lat. locatio placement) in animals, radiation and perception of reflected, usually high-frequency, sound signals in order to detect objects in space, as well as obtain information about the properties and... ... Great Soviet Encyclopedia

G. Orientation in space using reflected ultrasound. Ephraim's explanatory dictionary. T. F. Efremova. 2000... Modern explanatory dictionary of the Russian language by Efremova

echolocation- echolocation, and... Russian spelling dictionary

echolocation- echolocation/tion, and... Together. Separately. Hyphenated.

Books

• Entertaining wave research. Unrest and hesitation around us, Praetor-Pinney Gavin. G. Pretor-Pinney introduces everyone in a fun and easy way to the theory of waves, as well as the importance of waves in our everyday life. A trip around the world awaits you…

A. M. Reiman,
, IAP RAS, Nizhny Novgorod

What can ultrasound do?

Introduction and background

Let's start with the definition: “Ultrasound (US) is elastic vibrations and waves whose frequency exceeds 15–20 kHz. The upper limit of ultrasonic frequencies is determined by physical nature elastic waves and reaches 1 GHz." Behind this brief definition hides a huge world of acoustics, amazing with the variety of physical phenomena, the originality of technical solutions, and the very possibility of “hearing the inaudible.”

Like many other physical phenomena, ultrasonic waves owe their discovery to chance. In 1876, the English physicist Frank Galton While studying the generation of sound by whistles of a special design (Helmholtz resonators), which now bear his name, he discovered that at certain chamber sizes the sound ceases to be audible. One might have assumed that the sound simply was not emitted, but Galton concluded that the sound was not heard because its frequency became too high. In addition to physical considerations, this conclusion was supported by the reaction of animals (primarily dogs) to the use of such a whistle.

Galton whistle (Helmholtz resonator)

Obviously, it is possible to emit ultrasound using whistles, but it is not very convenient. The situation changed after the discovery of the piezoelectric effect Pierre Curie in 1880, when it became possible to emit sound without blowing the resonator with an air stream, but by applying an alternating electrical voltage to the piezoelectric crystal. However, despite the emergence of fairly convenient sources and receivers of ultrasound (the same piezoelectric effect makes it possible to convert the energy of acoustic waves into electrical vibrations) and the enormous successes of physical acoustics as a science associated with such names as William Strutt (Lord Rayleigh) Ultrasound was considered mainly as an object for study, but not for application.

Ultrasonic tomogram of a crack in metal

Ultrasound tomogram of the hand

The next step was taken in 1912, when just two months after the sinking of the Titanic, an Austrian engineer Alexander Bem created the world's first echo sounder. Imagine how history could have changed! From then until now, ultrasonic sonar has remained an indispensable tool for surface and underwater ships.

Another fundamental shift in the development of ultrasound technology was made in the 20s. XX century: in the USSR, the first experiments were carried out on sounding solid metal with ultrasound with reception at the opposite edge of the sample, and the recording equipment was designed so that it was possible to obtain two-dimensional shadow images of cracks in the metal, similar to X-ray (tube by S.A. Sokolov). Thus began ultrasonic flaw detection, which allows you to “see the invisible.”

Obviously, the use of ultrasound could not be limited to technical applications. In 1925, the outstanding French physicist Paul Langevin, engaged in equipping the fleet with echo sounders, studied the passage of ultrasound through human soft tissue and the effect of ultrasonic waves on the human body. Same S.A.Sokolov in 1938 he obtained the first “transmission” tomograms of a human hand. And in 1955, British engineers Ian Donald And Tom Brown built the world's first ultrasound tomograph, in which a person was immersed in a bath of water, and an operator with an ultrasound emitter and ultrasound receiver had to walk around the research object in a circle. They were the first to apply the principle of echolocation to humans and obtained not a transmissive, but a reflection tomogram.

The next fifty years (practically up to the present day) can be characterized as the era of the penetration of ultrasound into various areas of technical and medical diagnostics and the use of ultrasound in technological fields, where it often makes it possible to do what is impossible in nature. But more on this.

Echolocation in technology

The simplest type of echolocation is one-dimensional. A voltage pulse is applied to a radiating element (generator), which sends a short acoustic pulse into the medium. If on the way sound wave When an obstacle is encountered (an interface between layers with different acoustic properties, for example, a crack in metal), then part of the signal is reflected and can be received by a sensor, most often placed in the same place as the emitter. The signal is converted into electrical, amplified and appears on the screen.

To the principle of operation of a one-dimensional ultrasonic locator

By measuring the delay time of the received pulse relative to the emitted one τ and knowing the speed of sound in the medium c, you can determine the distance L to reflector: L = cτ/2. Obviously, in real conditions it is necessary to take measures to ensure that the echolocator does not show weak targets to avoid false alarms. To achieve this, there are procedures for assessing the minimum threshold level of detection sensitivity. In addition, it is reasonable to limit yourself to a certain area of ​​interest according to L, excluding from it the near zone, where there is always powerful interference, and the far zone, where the useful signal becomes comparable in amplitude to noise. If we add to this the control of the received signal gain (and it can be made dependent on the range in order to compensate for the weakening of the signal with distance), we get a universal echolocator that, with minor variations, can be used to solve many problems of technical and medical diagnostics.

Pioneers of ultrasonic location: F. Galton, A. Boehm, S. A. Sokolov, T. Brown And J.Donald

In echolocation technology, several large classes can be distinguished - level gauges, thickness gauges, echo sounders, flaw detectors. They differ mainly in the algorithms for using the received acoustic information, while the basis for each of them is still the one-dimensional echolocator described above. For example, if you place an ultrasound probe (which contains the emitting and receiving elements) on the bottom of a closed container with liquid, you will be able to measure its level without looking into the container, which may contain a poisonous or flammable substance. If we do not know the acoustic properties of this liquid, we can put a second one, the so-called supporting, probe onto the side wall of this container and determine the liquid level in relation to the delay times of the vertical and horizontal signals. An example of such a level gauge is a level meter for a natural gas odorant (mercaptan) in a container that is always closed, and even buried in the ground.

Ultrasonic devices: left– Ultrasonic level gauge; top right– Ultrasonic flaw detector for non-destructive testing of small parts; down– Ultrasonic thickness gauge

Ultrasonic thickness gauges are used for continuous measurements of sheet thickness (steel, glass) during production, as well as the thickness of an object that is accessible only from one side (for example, the wall thickness of a container or pipe). Here we often have to deal with very small delays, so to improve the accuracy of measurements, echolocator cycling is used: the first received echo signal immediately triggers the transmitter to emit the next pulse, etc., and it is not the delay time that is measured, but the trigger frequency.

Echo sounders, the development of which began almost a hundred years ago, are now used on a wide variety of objects, from surface and underwater military ships to inflatable boats of amateur fishermen. The use of computers made it possible not only to display the bottom profile on the echo sounder screen, but also to recognize the type of reflecting object (fish, driftwood, clot of silt, etc.). Using echo sounders, shelf profile maps are compiled; daily fluctuations in the depth of the plankton layer in the ocean have been discovered.

Rail ultrasonic flaw detector ADS-02

Acutely defective rail at a break

Perhaps the most important application of echolocation in technology is non-destructive testing of structures (metal, concrete, plastic) to identify defects in them caused by mechanical loads. In the simplest case, a flaw detector is an echolocator, on the screen of which an echogram is displayed. By moving the ultrasonic sensor along the surface of the controlled product, cracks can be detected. Typically, a flaw detector is equipped with a set of ultrasonic transducers that allow ultrasound to be introduced into the material at different angles, and an audible alarm for exceeding the threshold by the reflected echo signal.

Among metal structures, the most important object of non-destructive testing is railway rails. Despite significant successes in the implementation of automation tools, railways In Russia, manual control is most common. The multichannel echolocator is installed on a removable cart, which is pushed by the operator. Ultrasonic sensors are installed in skis sliding along the rail surface. To ensure acoustic contact, tanks with a contact liquid are installed on the trolley (water in summer, alcohol in winter). And thousands of operators walk along all railways, pushing carts, in snow and rain, in heat and frost... The requirements for the design of the equipment are high - the devices must operate in the temperature range from -40 to +50 ° C, be dust-proof, operate from battery The first domestic rail flaw detectors in the USSR were created 50 years ago by prof. A.K. Gurvich in Leningrad. Development computer technology has made it possible in the last decade to create automated flaw detectors that make it possible not only to detect a defect, but also to record the entire echogram of the path traveled for viewing information, storing it and further analyzing it in special centers. One of these devices - ADS-02 - was created by employees of our Institute of Applied Physics RAS together with the Meduza company and is mass-produced by the Nizhny Novgorod plant named after. M. Frunze. To date, more than 300 devices operate on Russian railways, helping to detect several thousand so-called acute defects, each of which can cause a crash. For the use of modern computer technologies, the ADS-02 flaw detector received 1st place in 2005 international competition developers of embedded systems in San Francisco (USA).

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Spatial orientation system

Direction:

Executor: 10th grade student Dmitry Tyukalov

Supervisor: Aminov Evgeniy Vitalievich

physics teacher

Introduction. 3

Chapter I. Echolocation. 4

I.1. Story. 4

I.2. Principles of echolocation. 4

I.3. Methods of application. 5

I.5. Principle of measurements. 12

I.6. Types of devices. 13

Chapter II. Arduino. 14

II.1. Application. 14

II.2. Programming language. 14

II.3. Differences from other platforms. 14

Conclusion. 18

List of references and Internet sources. 18

Application. 19

Introduction

Nowadays, people are gradually developing devices that make our lives easier. And of course, without orientation they would be incomplete. In this work, we will consider in detail one of the types of orientation - echolocation. The object of my research is orientation using the echolocation method, which we consider using the example of an autonomous device created on the basis of Arduino. The problem is whether it is convenient and effective.

The purpose of this work was: identifying the pros and cons of orientation based on the principle of echo location.

To achieve this goal, it is necessary to solve the following tasks:

1. Study the essence of the phenomenon.

2. Explore a stand-alone Arduino device.

3. Creating a device.

4. Writing a program.

5. Testing under various conditions.

6. Find a worthy use.

This issue has not been addressed in the past, but the phenomenon of echo location itself was considered by Pierre Curie in 1880, and its application in life became possible thanks to Alexander Boehm in 1912. He created the world's first echo sounder.

I guess that orientation based on the principle of echo location is very effective and can help people in life-threatening situations.

Chapter I. Echolocation

I would like to start from afar, namely with the definition:

Echolocation (echo and Latin locatio - “position”) is a method by which the position of an object is determined by the delay time of the return of the reflected wave. If the waves are sound, then this is sonar, if radio - radar.

I.1. Story

Echolocation as a phenomenon in robotics and mechanics comes from biology. Its discovery is associated with the name of the Italian naturalist Lazzaro Spallanzani. He noticed that bats fly freely in a completely dark room, without touching objects. In his experiment, he blinded several animals, but even after that they flew on a par with sighted ones. Spallanzani's colleague J. Zhurin conducted another experiment in which he covered the ears of bats with wax - and the animals bumped into all the objects. From this, scientists concluded that bats navigate by hearing. However, this idea was ridiculed by contemporaries, since nothing more could be said - short ultrasonic signals at that time were still impossible to record.

The idea of ​​active sound location in bats was first proposed in 1912 by H. Maxim. He proposed that bats create low-frequency echolocation signals by flapping their wings at a frequency of 15 Hz.

Ultrasound was discovered in 1920 by the Englishman H. Hartridge, who reproduced Spallanzani’s experiments. Confirmation of this was found in 1938 thanks to bioacoustician D. Griffin and physicist G. Pierce. Griffin proposed the name echolocation to name the way bats orient themselves using ultrasound.

I.2. Principles of echolocation

Echolocation begins with ultrasound, so let’s find out more about it.

Like many other physical phenomena, ultrasonic waves owe their discovery to chance. In 1876, the English physicist Frank Galton, studying the generation of sound by whistles of a special design (Helmholtz resonators), now bearing his name, discovered that at certain chamber sizes the sound ceases to be audible. One might have assumed that the sound simply was not emitted, but Galton concluded that the sound was not heard because its frequency became too high. In addition to physical considerations, this conclusion was supported by the reaction of animals (primarily dogs) to the use of such a whistle.

Obviously, it is possible to emit ultrasound using whistles, but it is not very convenient. The situation changed after the discovery of the piezoelectric effect by Pierre Curie in 1880, when it became possible to emit sound without blowing a stream of air through the resonator, but by applying an alternating electrical voltage to the piezoelectric crystal. However, despite the emergence of fairly convenient sources and receivers of ultrasound (the same piezoelectric effect makes it possible to convert the energy of acoustic waves into electrical vibrations) and the enormous successes of physical acoustics as a science associated with such names as William Strutt (Lord Rayleigh), ultrasound was considered mainly as an object for study, but not for application.

I.3. Methods of application

The next step was taken in 1912, when just two months after the sinking of the Titanic, an Austrian engineer Alexander Bem created the world's first echo sounder. Imagine how history could have changed! From then until now, ultrasonic sonar has remained an indispensable tool for surface and underwater ships.

Another fundamental shift in the development of ultrasound technology was made in the 20s. XX century: in the USSR, the first experiments were carried out on sounding solid metal with ultrasound with reception at the opposite edge of the sample, and the recording equipment was designed so that it was possible to obtain two-dimensional shadow images of cracks in the metal, similar to X-ray (tube by S.A. Sokolov). Thus began ultrasonic flaw detection, which allows you to “see the invisible.”

Obviously, the use of ultrasound could not be limited to technical applications. In 1925, the outstanding French physicist Paul Langevin, engaged in equipping the fleet with echo sounders, studied the passage of ultrasound through human soft tissue and the effect of ultrasonic waves on the human body. Same S.A.Sokolov in 1938 he obtained the first “transmission” tomograms of a human hand. And in 1955, British engineers Ian Donald And Tom Brown built the world's first ultrasound tomograph, in which a person was immersed in a bath of water, and an operator with an ultrasound emitter and ultrasound receiver had to walk around the research object in a circle. They were the first to apply the principle of echolocation to humans and obtained not a transmissive, but a reflection tomogram.

The next fifty years (practically up to the present day) can be characterized as the era of the penetration of ultrasound into various areas of technical and medical diagnostics and the use of ultrasound in technological fields, where it often makes it possible to do what is impossible in nature. But more on this.

Perhaps the most important application of echolocation in technology is non-destructive testing of structures (metal, concrete, plastic) to identify defects in them caused by mechanical loads. In the simplest case, a flaw detector is an echolocator, on the screen of which an echogram is displayed. By moving the ultrasonic sensor along the surface of the controlled product, cracks can be detected. Typically, a flaw detector is equipped with a set of ultrasonic transducers that allow ultrasound to be introduced into the material at different angles, and an audible alarm for exceeding the threshold by the reflected echo signal.

Among metal structures, the most important object of non-destructive testing is railway rails. Despite significant successes in the introduction of automation equipment, manual control is most common on Russian railways. The multichannel echolocator is installed on a removable cart, which is pushed by the operator. Ultrasonic sensors are installed in skis sliding along the rail surface. To ensure acoustic contact, tanks with a contact liquid are installed on the trolley (water in summer, alcohol in winter). And thousands of operators walk along all railways, pushing carts, in snow and rain, in heat and frost... The requirements for the design of the equipment are high - the devices must operate in the temperature range from -40 to +50 ° C, be dust-proof, operate from battery The first domestic rail flaw detectors in the USSR were created 50 years ago by prof. A.K. Gurvich in Leningrad. The development of computer technology has made it possible in the last decade to create automated flaw detectors that make it possible not only to detect a defect, but also to record the entire echogram of the path traveled for viewing information, its storage and further analysis in special centers. One of these devices - ADS-02 - was created by employees of our Institute of Applied Physics RAS together with the Meduza company and is mass-produced by the Nizhny Novgorod plant named after. M. Frunze. To date, more than 300 devices operate on Russian railways, helping to detect several thousand so-called acute defects, each of which can cause a crash. For the use of modern computer technologies, the ADS-02 flaw detector received 1st place in the international competition for embedded systems developers in San Francisco (USA) in 2005.

Ultrasonic thickness gauges are used for continuous measurements of sheet thickness (steel, glass) during production, as well as the thickness of an object that is accessible only from one side (for example, the wall thickness of a container or pipe). Here we often have to deal with very small delays, so to improve the accuracy of measurements, echolocator cycling is used: the first received echo signal immediately triggers the transmitter to emit the next pulse, etc., and it is not the delay time that is measured, but the trigger frequency.

Echo sounders, the development of which began almost a hundred years ago, are now used on a wide variety of objects, from surface and underwater military ships to inflatable boats of amateur fishermen. The use of computers made it possible not only to display the bottom profile on the echo sounder screen, but also to recognize the type of reflecting object (fish, driftwood, clot of silt, etc.). Using echo sounders, shelf profile maps are compiled; daily fluctuations in the depth of the plankton layer in the ocean have been discovered.

Unlike X-ray and NMR tomographs (as well as the first “transmission” ultrasound devices), modern devices for ultrasound examination of organs (ultrasound) operate in the same mode as their counterparts in technical diagnostics, i.e. detect interfaces between media with different acoustic characteristics. The difference between the properties of soft tissues does not exceed 10%, and only bone tissue give almost 100% reflection. Thus, almost all the wealth of information obtained by medical ultrasound devices lies in the analysis of these weak signals.

One of the first applications of one-dimensional location in medicine was the ultrasound echoencephaloscope. Its idea is simple: echograms of intracranial structures are obtained by probing the head in the temporal region on the left and right. The appearance of intracranial injuries (hematomas, tumors) leads to disruption of the symmetry of echograms, and such patients are easy to identify and refer for a more detailed and expensive examination.

The use of ultrasound in cardiology has led to the development of an important technology for ultrasound - representation of the echogram in depth-time coordinates, when the signal amplitude is represented by the gray level. This made it possible to begin systematic non-invasive studies of the movement of internal structures of the heart and large vessels and obtain new important physiological information. For example, it has been proven that the cross-section of the aorta does not change, as doctors previously assumed.

The first cardiac devices were one-dimensional, and the probe had to be rotated at different angles to study different structures. Subsequently, it was possible to automate this process, and modern ultrasound devices became echotomographs, i.e. allow you to obtain two-dimensional sections of the studied area of ​​​​the body and observe rapid movement structural elements heart - valves, septa. In the case of fixed structures, everything is much simpler. The first ultrasound tomograms were obtained when there were no complex electronics and computers, however, for this it was necessary to immerse a person in a bath of water and walk around in a circle with a one-dimensional sensor. Nowadays, methods of interference of oscillations from many small elements are used, which make it possible to control the direction of the ultrasonic beam. Such an ultrasound examination of organs and tissues has become a common procedure, incomparably cheaper than other types of tomography.

At the same time, private applications of one-dimensional ultrasonic location remained. One of them is to measure the thickness of the subcutaneous fat layer, which allows you to estimate an indicator of obesity, for example, BFI. This method is implemented in the Bodymetrix2000 device, a joint Russian-American development, which is now used in beauty salons and fitness clubs around the world.

Perhaps the most interesting of the complex modern devices for ultrasound medical diagnostics are three-dimensional systems. In these systems, the ultrasound beam is rotated in two mutually perpendicular directions, and the received echo signals are processed so as to obtain an image of the continuous surface of an object located inside the human body, be it internal organ or embryo. If the collection and processing of information occurs quickly enough, then it is possible to observe the movement of an object in real time, for example, to study the behavior of an unborn child, its reactions, etc. Perhaps the only question here is ensuring safety, i.e. maintaining the intensity of ultrasonic radiation at the level of 50–100 mW/cm2.

The discovery of echolocation is associated with the name of the Italian naturalist Lazzaro Spallanzani. He noticed that bats fly freely in a completely dark room (where even owls find themselves helpless), without touching objects. In his experiment, he blinded several animals, but even after that they flew on a par with sighted animals. Spallanzani's colleague J. Zhurin conducted another experiment in which he covered the ears of bats with wax - and the animals bumped into all the objects. From this, scientists concluded that bats navigate by hearing. However, this idea was ridiculed by contemporaries, since nothing more could be said - short ultrasonic signals at that time were still impossible to record.

The idea of ​​active sound location in bats was first proposed in 1912 by H. Maxim. He proposed that bats produce low-frequency echolocation signals by flapping their wings at a frequency of 15 Hz.

Ultrasound was discovered in 1920 by the Englishman H. Hartridge, who reproduced Spallanzani’s experiments. Confirmation of this was found in 1938 thanks to bioacoustician D. Griffin and physicist G. Pierce. Griffin suggested the name echolocation(similar to radar) to name the method of orienting bats using ultrasound.

Echolocation in animals

Animals use echolocation to navigate in space and to determine the location of objects around them, mainly using high-frequency sound signals. It is most developed in bats and dolphins; it is also used by shrews, a number of species of pinnipeds (seals), birds (guajaros, swiftlets, etc.).

The origin of echolocation in animals remains unclear; it probably arose as a substitute for vision among those who live in the darkness of caves or the depths of the ocean. Instead of a light wave, sound began to be used for location.

This method of orientation in space allows animals to detect objects, recognize them and even hunt in conditions of complete absence of light, in caves and at considerable depth.

Among arthropods, echolocation has been found only in nocturnal moths.

A person, in some way, also uses echolocation: after hearing a sound in a room, a person can determine the approximate volume of the room, the softness of the walls, etc.

Technical support for echolocation

Echolocation can be based on the reflection of signals of various frequencies - radio waves, ultrasound and sound. The first echolocation systems sent a signal to a certain point in space and, based on the response delay, determined its distance, given the known speed of movement of a given signal in a given environment and the ability of the obstacle to which the distance was measured to reflect this type of signal. Inspecting a section of the bottom in this way using sound took considerable time.

Nowadays, various technical solutions are used with the simultaneous use of signals of different frequencies, which can significantly speed up the echolocation process.

See also

• Sonar (sonar)

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Notes

Bibliography

• Sergeev B.F.. - L.: Gidrometeoizdat, 1980. - 150 p.
• Griffin D. R. Echoes in the lives of people and animals. Per. from English K. E. Wheeler. Ed. M. A. Isakovich.- M.: Fizmatgiz, 1961. - 110 p.

An excerpt characterizing echolocation

The next day after being admitted to the lodge, Pierre sat at home, reading a book and trying to understand the meaning of the square, which depicted God on one side, moral on the other, physical on the third, and mixed on the fourth. From time to time he looked up from the book and the square and in his imagination made up new plan life. Yesterday in the box he was told that a rumor about a duel had reached the sovereign's attention, and that it would be prudent for Pierre to leave St. Petersburg. Pierre intended to go to his southern estates and take care of his peasants there. He happily thought about this new life, when suddenly Prince Vasily entered the room.
– My friend, what have you done in Moscow? Why did you quarrel with Lelya, mon сher? [my dear?] “You are mistaken,” said Prince Vasily, entering the room. “I found out everything, I can tell you correctly that Helen is innocent before you, like Christ before the Jews.” - Pierre wanted to answer, but he interrupted him. “And why didn’t you address me directly and simply as a friend?” “I know everything, I understand everything,” he said, “you behaved as befits a person who values ​​​​his honor; It may be too hasty, but we won’t judge that. Just remember the position in which you place her and me in the eyes of the whole society and even the court,” he added, lowering his voice. – She lives in Moscow, you are here. Remember, my dear,” he pulled him down by the hand, “there is one misunderstanding here; I think you feel it yourself. Write a letter with me now, and she will come here, everything will be explained, otherwise I’ll tell you, you can get hurt very easily, my dear.
Prince Vasily looked at Pierre impressively. “I know from good sources that the Empress Dowager takes a keen interest in this whole matter.” You know, she is very merciful to Helen.
Several times Pierre was going to speak, but on the one hand, Prince Vasily did not allow him to do so, on the other hand, Pierre himself was afraid to start speaking in that tone of decisive refusal and disagreement in which he firmly decided to answer his father-in-law. In addition, the words of the Masonic charter: “be kind and friendly” came to his mind. He winced, blushed, stood up and fell down, working on himself in the most difficult task in his life - to say something unpleasant to a person’s face, to say something that was not what that person expected, no matter who he was. He was so accustomed to obeying this tone of Prince Vasily’s careless self-confidence that even now he felt that he would not be able to resist it; but he felt that everything would depend on what he said now further fate him: will he follow the old, former path, or along that new one, which was so attractively shown to him by the Masons, and on which he firmly believed that he would find rebirth to a new life.
“Well, my dear,” said Prince Vasily jokingly, “tell me: “yes,” and I will write to her on my own behalf, and we will kill the fat calf.” - But Prince Vasily did not have time to finish his joke, when Pierre, with a fury in his face that reminded him of his father, without looking into the eyes of his interlocutor, said in a whisper:
- Prince, I didn’t call you to my place, go, please, go! “He jumped up and opened the door for him.
“Go,” he repeated, not believing himself and rejoicing at the expression of embarrassment and fear that appeared on Prince Vasily’s face.
- What's wrong with you? Are you sick?
- Go! – the trembling voice spoke again. And Prince Vasily had to leave without receiving any explanation.
A week later, Pierre, having said goodbye to his new friends, the Freemasons, and leaving them large sums of alms, left for his estates. His new brothers gave him letters to Kyiv and Odessa, to the Freemasons there, and promised to write to him and guide him in his new activities.