Indeed, dogs can be guided not only by the smell of the individual who left the mark, but also by such signs as depressions in the soil, crushed grass, etc. It all depends on the quality of training and the fitness of the bloodhound. Mistakes made by the trainer during its preparation can lead to the fact that the dog can use visible traces or bright accompanying smells as a “hint”.
At the beginning of the century, such doubts significantly impeded the development of detective dog breeding. Nevertheless, there have always been supporters of the use of bloodhounds in the police service. By the 20s of our century, dogs were used in police units in most European countries. American L. Fuld, who studied European experience with the use of search dogs, strongly advised the use of specially trained bloodhounds in the US police. And E. Reed, the author of the first works devoted to the study of the structure of olfactory analyzers of dogs, domestic cats and humans and the comparison of their level of smell, pointed out that dogs have excellent sense of smell and are much better at smelling people.
In 1902, Doberman Pinschers appeared in Russia, in 1904 German shepherds were imported from Germany. In 190b, dogs appeared in the police service, first in the Baltic provinces, and in 1907 in St. Petersburg, where a police dog kennel was created. In the fall of 1908, the Russian Society for the Promotion of the Use of Dogs in Police and Watchdog Services was established. Police dogs were trained to search for criminals in hot pursuit of the crime scene, to search the area where the offender could hide or throw away some thing, as well as select objects on which a particular person left his smell. The work of a police dog, in addition to the investigator dog, usually also involved the work of detaining, escorting, protecting a person-counselor. Experiments with the use of police dogs for search purposes have been quite successful.
In 1909, in Moscow, Doberman received wide popularity Clubs. His exploits for those years became legendary.
For example, once in the village of Kuznetsovo, Bronnitsky district, three criminals committed the murder of a 60-year-old peasant Grishakov. Tref followed in the footsteps of the killers 115 km and eventually overtook them. All of them were arrested by the police.
In 1912, at the Izmailovsky Guards Regiment in Moscow, a kennel was established for breeding and training military field dogs. Airedale terriers were mainly bred in this kennel: it was believed that they were the most hardy and most suitable for work in Russian conditions, as a sanitary dog.
After the revolution, in 1923, Central courses for instructors were created, which trained border guards with search and guard dogs for service at the border, and in 1924 in the village of Veshnyaki near Moscow, an experienced kennel of military and sports dogs of the Red Army was founded. But search dogs were used by the police until that time. In the early 20s in St. Petersburg became famous Covenant - a sniffer dog that has detained more than one criminal. A German shepherd The sultan, another legendary bloodhound of the Leningrad Criminal Investigation Department, for 10 years from 1937 to 1947 he detained more than 2 thousand prisoners, discovered a huge amount of stolen property.
During the military operations in Manchuria, the Red Army successfully used medical dogs. A large number of such dogs were trained during the Great Patriotic War. Minnow dogs were widely used in many armies. The first field trials of dogs of the Ministry of Forensics in the Soviet Army were conducted in December 1942. And in the same December, mine-seeker dogs received a baptism of fire near Stalingrad. Conducted military tests showed the failure-free operation of mine detector dogs and their ability to find mines disguised in the most complex way. Since the summer of 1943, dogs of the mine detection service received widespread recognition among the troops, and in the autumn of that year several separate battalions and companies with mine detection dogs were sent to the front: the 37th separate battalion of mine detection dogs and tank bombers was commanded by A. Mazover, subsequently leading Soviet cynologist. The data that the mine detection dogs used in the Soviet Army found more than 4 million mines, landmines and other charges during the war years became a textbook. They cleared hundreds of villages, towns, cities, including Kharkov, Kiev, Warsaw, Vienna. After a period of great interest in studying the sense of smell of dogs at the turn of the century, in the thirties and forties of the twentieth century there was a slight decline in the study of this problem. But since the fifties, there has been a gradual increase in the number of studies devoted to this topic.
The work of the British, the biologists of Kalmus and Becker, became classic.
Kalmus called the smell by which the dog is looking for a person individual. He didn’t even take seriously the doubts of the researchers of the beginning of the century that it was more important for a dog to see a track than to smell it, and a significant part of his experimental work was carried out by experiments that used the ability of dogs to follow a man’s fragrant footprint. He believed that the smell of a person does not depend on clothing, food, home furnishings. However, sometimes the individuality of the human smell “malfunctioned”. In one experiment, two twin brothers of thirty-three years participated, both were married and lived in different places. If a dog was allowed to smell a thing with the smell of one twin, it would perfectly follow the trail of the other, provided that only the second twin participated in this experiment. However, when the twins diverged in different directions and hid, the dog was able to track down exactly the twin whose smell she remembered before conducting the experiment. From this it is clear that identical twins have very similar smells, but still not quite the same. Kalmus notes that in his experiments, the dog, confidently following the trail of one of the twins, was terribly embarrassed and excited when at the end of the track they both faced her. The German physiologist Neuhaus invented the simplest olfactometer device, with which you can determine the severity of smell. In experiments, he showed that the susceptibility to a number of substances in humans and dogs is not much different, at the same time, there are a number of substances to which dogs are thousands and millions of times more sensitive than humans. This applies, for example, to oil and other so-called
fatty acids. Neuhaus calculated that people should distinguish the smell of fresh human footprints, because the content of odorous substances in such prints is many times higher than the threshold concentration for smelling a person.
To this end, a simple experiment was carried out. Sheets of blank paper were laid on the floor, and one of the assistants walked barefoot through them at normal speed. After about thirty seconds, these sheets were given to another person with a good sense of smell, and he confidently, only by smell, determined the place of the foot print.
The author of this article had to work in nature reserves. And I can say with confidence that a person can smell a bear’s paw print even several hours after the beast has passed. However, the smell of a human footprint depends on the presence of tens and hundreds of various substances in it. Therefore, when the Neuhaus began to give the dog a sniff of more or less complex mixtures of substances, it turned out that in this case the sensitivity of the dog’s nose to many substances becomes even higher. That is, separately, two or three substances in negligible amounts could not be perceived by the dog, and she recognized the mixture of these substances, even if the total amount of the mixture was insignificant.
As a result of all these experiments, the scientist came to the conclusion that the dog distinguishes the individual smell of a person not by the presence of any one odorous substance. peculiar to this particular person, and most likely due to a certain set of substances, which even in sub-threshold quantities together create a special individual smell. The severity of the sense of smell of dogs was one of the main topics in the work of many researchers. They tried to measure, compare, raise it. We looked for factors on which this quality of dogs depends. At Moscow University and the Krasnaya Zvezda nursery, led by General G. Medvedev, over the years, such studies were conducted under the guidance of the most prominent scientist L. V. Krushinsky. As a result, certain successes were achieved in solving the problem of measuring and increasing the severity of flair. In the old days, hunters looked for signs of the exterior of dogs that would correlate with better flair.
Sometimes such a sign was considered a pink or bifurcated nose, sometimes, on the contrary, black and in no case not separated by a groove. It seemed to medieval European aristocrats that if the dog could not navigate by visual and acoustic signals, its sense of smell would be much sharper. Thus, for example, some European beagle breeds were bred: their low-set ears with a long and almost averted ear cone completely covered the ear canal and partly the eyes if the dog leaned towards the track. This symptom is most pronounced in modern bloodhounds: folds of skin on the head and long ears significantly reduce the dog’s ability to use all the senses, except for the sense of smell when the dog lowers its head - maybe that’s why they are considered to have the most delicate instincts. Attempts to pharmacological effects on the olfactory analyzer in order to increase the severity of flair have been repeatedly undertaken by researchers. However, all of them turned out to be of little effect. Therefore, in the end, experts agreed on the need to select dogs only in terms of the quality of their flair.
Some experimenters took a different path. They suggested, and not without reason, that the dog in the process of domestication could lose many of the qualities inherent in its wild ancestors.
This may concern both the behavior and sensitivity of the analyzers - vision, hearing and smell. Based on common sense, they recognized the most promising use for the restoration of such qualities is the hybridization of domestic dogs with their wild relatives. Since the 30s, the Dutchman Lindert Saarlos began the systematic work on creating the Saarlos Wolfhund by hybridizing the German Shepherd and Wolves, and in 1942 the Czech engineer Karel Hartl began work on the development of the Czech Wolf Dog. In 1989, the breed was recognized by FCI.
In the 60s, a group of German researchers carried out work on the hybridization of poodles with wolves and jackals. In our country, the hybridization of dogs with jackals in the mid-70s began K.T.Sulimov. Currently, American lovers continue to attempt hybridization of dogs with wild canids. These animals are very popular among dog lovers in America. It is noteworthy that the keeping of hybrid animals in the USA, due to the unpredictability of their behavior and the danger of penetration into the population of wild animals and crossing with savages, is allowed only if they are castrated. The optimal proportion of the genotype of wild animals in hybrid individuals, according to different researchers, varies greatly. Most believe that 50 percent hybrids more fully retain canine qualities, but the genes of wild animals greatly improve their performance and sensory abilities. K.T.Sulimov believes that hybrids with 25% of the blood of the savage and 75% of the blood of the dog are the most suitable for work, K. Hartle is convinced that the desired ratio is 10% of the wild beast and 90% of the dog. All researchers working with hybrid animals note good trainability, excellent sensory abilities, but at the same time some character difficulties that limit the possibility of widespread use in practice: incredulity, timidity, and a tendency to vagrancy.
Traditionally, German and Belgian shepherds and Labradors are used as search dogs. To a lesser extent - spaniels, bloodhounds, Dobermans, beagles.
Isolated examples of the use of, for example, staffordshires as search dogs and keskhondas, as odor detection dogs, are known.
Dogs were used in the US Army during the Vietnam War as watchdogs. According to the experts who applied them, the dogs could clearly distinguish the smells of American soldiers and Vietnamese, giving a signal only when the enemy approached.
In the late sixties and early seventies, the problem of combating drugs became an acute problem in many countries. And here the dog nose was simply irreplaceable. Dogs began to be widely used in the customs service for the detection of narcotic drugs, in the police for the search of drug traffickers.
Counterterrorism units use dogs to detect explosives and weapons. And in this case, dogs work much more efficiently than technical detectors. In many countries, special schools have been set up to train such dogs. Search dogs are used in various exotic projects.
Experiments are known when dogs successfully searched for ore deposits.
There have been attempts to use the sense of smell of dogs to detect gas leaks in gas pipelines. In the Scandinavian countries, specially trained labradors are looking for telegraph poles affected by the fungus - and experts believe that dogs do this much more successfully than technical devices. A special service has been created in the USA in which beagles are used: bloodhounds find trees and buildings struck by termites and so far surpass specially designed devices in the search results. However, in these areas of application, dogs are increasingly being replaced by technology. This is how a person works - he trusts the readings of the device more than a living detector. Nevertheless, problems remain that are still not possible to solve using physicochemical methods.
Recognizing and identifying a person’s individual smell is one of the most difficult of these tasks, since the chemical nature of the individual smell is still unknown. Each individual constantly emits thousands of substances into the surrounding space, and none of them can say yet which odorous code of a particular person is.
With the help of instruments, it is possible to capture and identify the smallest quantities of a variety of substances, but the analysis of the mixture that a person emits is truly a titanic work: for this, each substance would have to be identified and its quantity determined. But the dog does not need to share the mixture, it perceives everything at once, just as an ordinary listener, hearing a piece of music performed by a symphony orchestra, does not try to decompose it into parts played by each instrument, analyze it by notes.
We remember the melody as a whole and can distinguish it from another without going into details. So the dog remembers the "melody" of the smell, not dividing it into parts. A canine odor recognition ability is sometimes compared to a black box. We can observe,
how a man went somewhere, how after a while a dog ran along the track. We can see how she finds this man. But what was happening at that time in the dog’s nose and in the dog’s head is hidden from us behind the family, no, perhaps already behind six seals. For a long time in the search service, the possibility of using dogs was limited by factors affecting the safety of odor traces. The dog could be used only when examining the scene of the incident or the prosecution of a hiding criminal.
In the 60s, a group of Soviet forensic scientists (A. Vinberg, V. Bezrukov, M. Mayorov, R. Todorov) developed methods for collecting and preserving odor samples. They suggested either hermetically packing material evidence bearing the smell of the elder, or, in the absence thereof, to take and preserve air with traces of smell and to keep such samples until the moment when the use of a service-search dog proves to be appropriate. Since that time, the development and formation of a new discipline, which the authors called judicial odorology, began in forensics ("odor" - smell, "logos" - science) Western European companies (Germany, Denmark), which produced devices and tools for working with traces at the scene, began to produce special containers for storing selected traces of odor. Samples of the smell from crime scenes began to be combined into original collections - “banks of smells”. With the help of technical means, attempts were made to identify individual odors, but they turned out to be complex and ineffective. Currently, only specially trained dogs can serve as detectors of individual odors.
In many European countries, cynological identification of individual odors is widely used in forensic practice.
In Russia, K.T.Sulimov became the founder of laboratory cynological odorology in forensics. Under his leadership, a laboratory was created, the implementation of this method in forensic practice was carried out. In addition to practical work, the laboratory solved many theoretical problems.
The researcher created a unique group of hybrid dogs that turned out to be suitable for the identification of a variety of odorous objects. The dog nose is likely to remain in demand in many areas of human activity for a long time to come. And the point is not only in the impossibility of creating technical devices that could replace it. Probably, our long-standing relationship with the dog, the ability and ability to understand each other play a big role. And this partnership, which has been going on for many thousands of years, cannot be broken overnight, replacing a wet, cold, leather nose with a soulless sensor, because devoted eyes and a faithful dog heart are inseparable from the nose!
Impedance, noise reduction and damping - what does it mean? Pickup Headphone Guide
You decided to buy headphones. Just headphones, not CERN's development, but terms and specifications demolished you with an avalanche of incomprehensible information. So that frightening contractions and unknown words no longer scare you, and in your hands are headphones that are ideal in terms of price and quality - we, together with the Sony mastodons, have compiled a simple guide for you without water. Why exactly with them? Yes, because almost any type of headphones that you can imagine is or was in their range.
Let's start with a simple one and see what kind of headphones there are by the type of bowl, sound and connection. The purity and volume of the sound depend on these parameters and whether the headphones are suitable for your lifestyle and goals.
Inserts - headphones that are inserted into the ear. “Droplets” are the simplest and first in the evolutionary chain. Due to the structure, the membrane does not have enough rigidity, therefore, “drops” weakly reproduce low frequencies.
A membrane is part of a speaker whose vibrations create sound. The sound is cooler if the membrane is light and stiff. Stiffness makes the sound clear, removes distortion, and lightness is also responsible for the volume of sounds.
In-ear headphones / vacuum / earplugs better hold because they "sit" directly in the ear canal. Due to the pads, they isolate external noise better than “drops”, and a light and rigid membrane makes the sound noticeably better. But due to the pressure inside, they can make the sound less natural than in the “drops”. In-ear headphones help to hear music well in the subway, airplane and public places, they immerse in music - most sports headphones are in this design.
Overhead placed on the ears - hence the name. They are held by the arch (head or occipital) or arches, if fastening around the ear. These headphones have larger and more rigid membranes, so the sound is better than the “droplets”. At the same time, there is sound insulation, as in intra-channel ones, but it is far from always better. Vacuum earphones can be inferior to noise canceling. Such headphones are not very convenient for transportation and usually sit at a working or home computer. This variety includes many gaming and music lovers.
Full Size / Monitor - Large, solid and expensive headphones. The design completely covers the ear, therefore, gives the maximum level of sound insulation and quality due to the large membrane. Such headphones are chosen by specialists who work with sound.
By type of construction
Open - they let air into the cup, so pressure does not form inside - the sound does not change and remains natural. Cons: the people around you will also hear this naturalness, in addition, there is poor noise reduction in such headphones - in addition to music, you will know everything that everyone around is talking about.
Closed - the sound falls only in the ears, and the air volume puts a strain on the speaker. Often suffer dips at low frequencies. People around you will not hear your music, and you will not hear others. Only music. But it will sound less natural than in open ones.
Half-open headphones - a cross between the two extreme types. They let in a little air, they isolate noise worse, but the sound is more natural and the ears do not sweat. Yes, this happens with overlays.
By connection type
Wired Headphones are directly connected to your device via cable. More often they are cheaper than wireless and have good sound, provided they have a high-quality cup and speaker. There is one minus: the infuriating confused wires and the need to keep them under clothes so that they do not cling to everything.
Wireless connecting to the device via Bluetooth takes us into a bright tech future. In budget models, sometimes they use a mediocre assembly and weak signal receivers, so the sound can be interrupted when moving and especially turning the head. Therefore, be sure to look at the specifications.
How to understand the terms in the description of the headphones and what they are responsible for
Let's say you saw an advertisement for the new Sony WH-XB900N headphone and decided to find out what chips are in them and what appeared new. You open the characteristics and clearly realize that the school did not prepare you well for this. But everything is not so scary.
Dynamic type The headphone reproduces sound thanks, logically, to the speakers built into the bowls. This type of headphone reproduces many deep shades of sound.
Reinforcing Headphones are most often intra-channel. In them, the membrane is arranged so that it limits the maximum volume and does not give deep bass.
IN planar headphones thin and lightweight membrane. They give a natural and very detailed sound, but as weak at low frequencies as reinforcing ones. At the same time, in order for the headphones to better reproduce bass, engineers have to increase the design. Therefore, planar headphones are most often found among full-size headphones.
Electrostatic Headphones provide the purest and most detailed sound. But here is the same story with the dimensions as in the case of planar headphones.
Resistance or impedance responsible for how loud the melody or voice of the interlocutor will sound.
Impedance is how the power output overcomes the DC resistance of the battery / accumulator and the reactance from the alternating current of the electrical network.
In practice, this means that if you connect professional studio headphones with 500 Ohms to a smartphone, it will not have enough power - current - to power these monsters. The sound will be clear, but very quiet. Moreover, the more Ohms, the cleaner the sound. Ideal for everyday use with gadgets: 16 to 50 ohms.
Playable frequencies - the wider the range, the richer the sound. The human ear picks up sounds from 15 to 20,000 Hz. Different shades of music and voice are scattered in this range, so ideally, headphones should cover the entire range. Sony WH-XB900N, when the cable is connected, has a sound from 2 to 20 000 Hz, via Bluetooth - the indicator is the same, but starts from 20 Hz.
Sensitivity responsible for how loud the sound will be. The standard is from 90 to 120 dB. For plugs and noise-canceling headphones, you can not chase the maximum performance. But with the inserts it’s better to choose a louder option - anyway, part of the sound in them is lost.
Noise suppression happens passive and active. Passive arises due to ear pads and earbuds. Active works on a digital level. Microphones pick up external sound, the integrated processor analyzes it. And along with the stream of music, the headphones emit a sound wave that dampens the noise. In fact, they create a “mirror” wave, which is superimposed on street sounds and becomes silence.
This technology appeared relatively recently, but has already captured the market. On the street, in the subway, airplane or cafe, active noise canceling headphones become a real salvation. It is not necessary to include music for the operation of the noise cutter. So if you are used to working in your favorite coffee shop, but at some point there are too many people there, noise canceling headphones isolate you from what is happening and keep silence. At the same time, you will hear sharp sounds, like a signal from a car on the street: here the technology is safe.
These are standard parameters that you should pay attention to. But if you laid eyes on the wireless model, appreciate these:
• is there a cord in the kit and how long is it - in case of insurance,
• type of wireless connection: NFC or Bluetooth,
• whether the headphones are charged from the case or wirelessly and how long it takes,
• how much and at what distance do they work.
The Sony WH-XB900N comes with a meter cable - suitable for viewing Netflix on a large screen so that your eyes do not spoil. The connection is not limited to Bluetooth, it works via NFC. The headphones hold the battery charge for a long time: up to 30 hours with a wireless connection and the noise canceling function turned on, during idle time - 300. In fact, this means that if you listen to the player on the road to work or study, the headphones will last for a week without recharging.
In addition to the basic criteria, each manufacturer tries to captivate the buyer with additional buns.
• Sony WH-XB900N does not require a microphone - it is built into the bowls,
• “Quick attention” function - you touch the bowl and the music is muffled,
• the sensor on the bowl flips through the tracks and touches the volume,
• convenient folding design - like full-size headphones, but compact,
• connection with Google Assistant, Alexa and sound settings through the application on the smartphone,
• authoring Sony EXTRA BASS interacts with active noise reduction - outputting a whole range of low frequencies and bass.
We walked along the most important parameters. Of course, among the characteristics of the headphones there is a membrane diameter, contact pressure, and harmonic coefficient. But all these indicators are so highly specialized that if you do not know about them, it means that they are not important for you. And to choose headphones was even easier, answer the questions in the diagram below. And good luck with your choice!