frequency range of hearing. Threshold of pain

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Informational

Features of human perception. Hearing

Sound is vibrations, i.e. periodic mechanical perturbation in elastic media - gaseous, liquid and solid. Such an outrage, which is some physical change in a medium (for example, a change in density or pressure, displacement of particles), propagates in it in the form of a sound wave. A sound may be inaudible if its frequency lies outside the sensitivity range. human ear, or it propagates in a medium such as a solid that cannot have direct contact with the ear, or its energy is rapidly dissipated in the medium. Thus, the usual process of sound perception for us is only one side of acoustics.

sound waves

Sound wave

sound waves can serve as an example of an oscillatory process. Any hesitation is associated with a violation equilibrium state system and is expressed in the deviation of its characteristics from equilibrium values with a subsequent return to the original value. For sound vibrations such a characteristic is the pressure at a point in the medium, and its deviation is the sound pressure.

Consider a long pipe filled with air. From the left end, a piston tightly adjacent to the walls is inserted into it. If the piston is sharply moved to the right and stopped, then the air in its immediate vicinity will be compressed for a moment. The compressed air will then expand, pushing the air adjacent to it on the right, and the area of compression, originally created near the piston, will move through the pipe at a constant speed. This compression wave is the sound wave in the gas.
That is, a sharp displacement of particles of an elastic medium in one place will increase the pressure in this place. Due to the elastic bonds of the particles, the pressure is transferred to neighboring particles, which, in turn, act on the next, and the area high blood pressure as if moving in an elastic medium. The area of high pressure is followed by the area reduced pressure, and thus, a series of alternating regions of compression and rarefaction is formed, propagating in the medium in the form of a wave. Each particle of the elastic medium in this case will oscillate.

A sound wave in a gas is characterized by excess pressure, excess density, displacement of particles and their speed. For sound waves, these deviations from the equilibrium values are always small. Thus, the excess pressure associated with the wave is much less than the static pressure of the gas. Otherwise, we are dealing with another phenomenon - a shock wave. In a sound wave corresponding to ordinary speech, the excess pressure is only about one millionth of atmospheric pressure.

It is important that the substance is not carried away by the sound wave. A wave is only a temporary perturbation passing through the air, after which the air returns to an equilibrium state.
Wave motion, of course, is not unique to sound: light and radio signals travel in the form of waves, and everyone is familiar with waves on the surface of water.

Thus, sound, in a broad sense, is elastic waves propagating in any elastic medium and creating mechanical vibrations in it; in a narrow sense - the subjective perception of these vibrations by special sense organs of animals or humans.
Like any wave, sound is characterized by amplitude and frequency spectrum. Usually a person hears sounds transmitted through the air in the frequency range from 16-20 Hz to 15-20 kHz. Sound below the human hearing range is called infrasound; higher: up to 1 GHz - by ultrasound, from 1 GHz - by hypersound. Among the audible sounds, one should also highlight phonetic, speech sounds and phonemes (of which oral speech) and musical sounds (of which music is composed).

There are longitudinal and transverse sound waves, depending on the ratio of the direction of propagation of the wave and the direction of mechanical oscillations of the particles of the propagation medium.
In liquid and gaseous media, where there are no significant fluctuations in density, acoustic waves are longitudinal in nature, that is, the direction of particle oscillation coincides with the direction of wave movement. IN solids, in addition to longitudinal deformations, elastic shear deformations also arise, causing the excitation of transverse (shear) waves; in this case, the particles oscillate perpendicular to the direction of wave propagation. The velocity of propagation of longitudinal waves is much greater than the velocity of propagation of shear waves.

Air is not uniform everywhere for sound. We know that air is constantly in motion. The speed of its movement in different layers is not the same. In layers close to the ground, the air comes into contact with its surface, buildings, forests, and therefore its speed here is less than at the top. Due to this, the sound wave does not travel equally fast at the top and bottom. If the movement of air, i.e., the wind, is a companion to the sound, then in the upper layers of the air the wind will drive the sound wave more strongly than in the lower ones. In a headwind, sound travels slower above than below. This difference in speed affects the shape of the sound wave. As a result of wave distortion, sound does not propagate in a straight line. With a tailwind, the line of propagation of a sound wave bends down, with a headwind - up.

Another reason for the uneven propagation of sound in the air. This - different temperature its individual layers.

Differently heated layers of air, like the wind, change the direction of the sound. During the day, the sound wave bends upward, because the speed of sound in the lower, warmer layers is greater than in the upper layers. In the evening, when the earth, and with it the surrounding layers of air, quickly cool down, the upper layers become warmer than the lower ones, the speed of sound in them is greater, and the line of propagation of sound waves bends downward. Therefore, in the evenings out of the blue it is better to hear.

When observing clouds, one can often notice how at different heights they move not only with different speed, but sometimes in different directions. This means that the wind at different heights from the ground can have different speed and direction. The shape of the sound wave in such layers will also vary from layer to layer. Let, for example, the sound goes against the wind. In this case, the sound propagation line should bend and go up. But if it meets a layer of slowly moving air on its way, it will change its direction again and may return to the ground again. It was then that in space from the place where the wave rises in height to the place where it returns to the ground, a "zone of silence" appears.

Organs of sound perception

Hearing - ability biological organisms perceive sounds with the organs of hearing; special function hearing aid, excited by sound vibrations environment such as air or water. One of the biological five senses, also called acoustic perception.

The human ear perceives sound waves with a length of approximately 20 m to 1.6 cm, which corresponds to 16 - 20,000 Hz (oscillations per second) when transmitting vibrations through the air, and up to 220 kHz when transmitting sound through the bones of the skull. These waves have important biological significance, for example, sound waves in the range of 300-4000 Hz correspond to the human voice. Sounds above 20,000 Hz have little practical value, because they slow down quickly; vibrations below 60 Hz are perceived through the vibrational sense. The range of frequencies that a person is able to hear is called the auditory or sound range; higher frequencies are called ultrasound and lower frequencies are called infrasound.
The ability to distinguish sound frequencies is highly dependent on the individual: his age, gender, susceptibility to auditory diseases, training and hearing fatigue. Individuals are able to perceive sound up to 22 kHz, and possibly even higher.
A person can distinguish several sounds at the same time due to the fact that there can be several standing waves in the cochlea at the same time.

The ear is a complex vestibular-auditory organ that performs two functions: it perceives sound impulses and is responsible for the position of the body in space and the ability to maintain balance. This paired organ, which is located in the temporal bones of the skull, limited to the outside by the auricles.

The organ of hearing and balance is represented by three sections: the outer, middle and inner ear, each of which performs its specific functions.

The outer ear consists of the auricle and the external auditory meatus. The auricle is a complex-shaped elastic cartilage covered with skin, its Bottom part, called the lobe, - skin fold which is made up of skin and adipose tissue.
The auricle in living organisms works as a receiver of sound waves, which are then transmitted to inner part hearing aid. The value of the auricle in humans is much less than in animals, so in humans it is practically motionless. But many animals, moving their ears, are able to determine the location of the sound source much more accurately than humans.

The folds of the human auricle are brought into the incoming ear canal sound small frequency distortion, depending on the horizontal and vertical localization of the sound. Thus the brain receives Additional information to locate the sound source. This effect is sometimes used in acoustics, including to create a sense of surround sound when using headphones or hearing aids.
The function of the auricle is to pick up sounds; its continuation is the cartilage of the external auditory canal, the average length of which is 25-30 mm. cartilaginous part the auditory canal passes into the bone, and the entire external auditory canal is lined with skin containing sebaceous and sulfuric glands, which are modified sweat glands. This passage ends blindly: it is separated from the middle ear by the tympanic membrane. Caught auricle sound waves hit eardrum and cause it to vibrate.

In turn, the vibrations of the tympanic membrane are transmitted to the middle ear.

Middle ear
The main part of the middle ear is tympanic cavity- a small space with a volume of about 1 cm³, located in temporal bone. Here are three auditory ossicles: hammer, anvil and stirrup - they transmit sound vibrations from the outer ear to the inner, while amplifying them.

Auditory ossicles - as the smallest fragments of the human skeleton, represent a chain that transmits vibrations. The handle of the malleus is closely fused with the tympanic membrane, the head of the malleus is connected to the anvil, and that, in turn, with its long process, to the stirrup. The base of the stirrup closes the window of the vestibule, thus connecting with the inner ear.
The middle ear cavity is connected to the nasopharynx by eustachian tube, through which the average air pressure inside and outside of the eardrum equalizes. When it changes external pressure sometimes "lays" the ears, which is usually solved by the fact that yawning is reflexively caused. Experience shows that even more effectively stuffy ears are solved by swallowing movements or if at this moment you blow into a pinched nose.

inner ear
Of the three parts of the organ of hearing and balance, the most complex is the inner ear, which, because of its intricate shape, is called the labyrinth. The bony labyrinth consists of the vestibule, cochlea, and semicircular canals, but only the cochlea, filled with lymphatic fluids, is directly related to hearing. Inside the snail is membranous canal, also filled with liquid, on the lower wall of which the receptor apparatus is located auditory analyzer covered with hair cells. Hair cells pick up fluctuations in the fluid that fills the canal. Each hair cell is tuned to a specific audio frequency, and the cells tuned to low frequencies, are located in the upper part of the cochlea, and high frequencies are captured by the cells of the lower part of the cochlea. When hair cells die from age or for other reasons, a person loses the ability to perceive sounds of the corresponding frequencies.

Limits of Perception

The human ear nominally hears sounds in the range of 16 to 20,000 Hz. The upper limit tends to decrease with age. Most adults cannot hear sound above 16 kHz. The ear itself does not respond to frequencies below 20 Hz, but they can be felt through the sense of touch.

The range of perceived sounds is huge. But the eardrum in the ear is only sensitive to changes in pressure. The sound pressure level is usually measured in decibels (dB). The lower limit of audibility is defined as 0 dB (20 micropascals), and the definition of the upper limit of audibility refers more to the threshold of discomfort and then to hearing loss, contusion, etc. This limit depends on how long we listen to the sound. The ear can tolerate short-term volume increases of up to 120 dB without consequences, but long-term exposure to sounds above 80 dB can cause hearing loss.

More thorough research lower bound Hearing studies have shown that the minimum threshold at which sound remains audible depends on the frequency. This graph is called the absolute threshold of hearing. On average, it has a region of greatest sensitivity in the range of 1 kHz to 5 kHz, although sensitivity decreases with age in the range above 2 kHz.
There is also a way to perceive sound without the participation of the eardrum - the so-called microwave auditory effect, when modulated radiation in the microwave range (from 1 to 300 GHz) affects the tissues around the cochlea, causing a person to perceive various sounds.
Sometimes a person can hear sounds in the low frequency region, although in reality there were no sounds of such a frequency. This is due to the fact that the oscillations of the basilar membrane in the ear are not linear and oscillations with a difference frequency between two higher frequencies can occur in it.

Synesthesia

One of the most unusual neuropsychiatric phenomena, in which the type of stimulus and the type of sensations that a person experiences do not match. Synesthetic perception is expressed in the fact that in addition to the usual qualities, additional, simpler sensations or persistent "elementary" impressions may occur - for example, colors, smells, sounds, tastes, qualities of a textured surface, transparency, volume and shape, location in space and other qualities. , not received with the help of the senses, but existing only in the form of reactions. Such additional qualities may either arise as isolated sense impressions or even manifest physically.

There is, for example, auditory synesthesia. This is the ability of some people to "hear" sounds when observing moving objects or flashes, even if they are not accompanied by real sound phenomena.
It should be borne in mind that synesthesia is rather a neuropsychiatric feature of a person and is not mental disorder. This perception of the surrounding world can feel a common person through the use of certain drugs.

There is no general theory of synesthesia (scientifically proven, universal idea about it) yet. At the moment, there are many hypotheses and a lot of research is being carried out in this area. Original classifications and comparisons have already appeared, and certain strict patterns have emerged. For example, we scientists have already found out that synesthetes have a special nature of attention - as if "preconscious" - to those phenomena that cause them synesthesia. Synesthetes have a slightly different brain anatomy and a radically different activation of it to synesthetic “stimuli”. And researchers from Oxford University (UK) set up a series of experiments during which they found out that hyperexcitable neurons can be the cause of synesthesia. The only thing that can be said for sure is that such perception is obtained at the level of the brain, and not at the level of the primary perception of information.

Conclusion

Pressure waves passing through outer ear, tympanic membrane and ossicles of the middle ear reach the fluid-filled inner ear having the shape of a snail. The liquid, oscillating, hits a membrane covered with tiny hairs, cilia. The sinusoidal components of a complex sound cause vibrations in various parts of the membrane. The cilia that vibrate along with the membrane excite the associated nerve fibers; in them there are series of pulses in which the frequency and amplitude of each component of a complex wave are “encoded”; these data are electrochemically transmitted to the brain.

Of the entire spectrum of sounds, first of all, they distinguish audible range: from 20 to 20,000 hertz, infrasounds (up to 20 hertz) and ultrasounds - from 20,000 hertz and above. A person does not hear infrasounds and ultrasounds, but this does not mean that they do not affect him. It is known that infrasounds, especially below 10 hertz, can affect the human psyche, cause depressive states. Ultrasounds can cause astheno-vegetative syndromes, etc.
The audible part of the range of sounds is divided into low-frequency sounds - up to 500 hertz, mid-frequency sounds - 500-10000 hertz and high-frequency sounds - over 10000 hertz.

This division is very important, since the human ear is not equally sensitive to different sounds. The ear is most sensitive to a relatively narrow range of mid-frequency sounds from 1000 to 5000 hertz. For lower and higher frequency sounds, the sensitivity drops sharply. This leads to the fact that a person is able to hear sounds with an energy of about 0 decibels in the mid-frequency range and not hear low-frequency sounds of 20-40-60 decibels. That is, sounds with the same energy in the mid-frequency range can be perceived as loud, and in the low-frequency range as quiet or not be heard at all.

This feature of sound is formed by nature not by chance. The sounds necessary for its existence: speech, the sounds of nature, are mainly in the mid-frequency range.
The perception of sounds is significantly impaired if other sounds sound at the same time, noises that are similar in frequency or composition of harmonics. This means that, on the one hand, the human ear does not perceive low-frequency sounds well, and, on the other hand, if there are extraneous noises in the room, then the perception of such sounds can be even more disturbed and distorted.

It is known that 90% of information about the world around a person receives with vision. It would seem that there is not much left to hear, but in fact, human organ hearing aid is not only a highly specialized sound vibration analyzer, but also a very powerful tool communications. Doctors and physicists have long been concerned about the question: is it possible to accurately determine the range of human hearing in different conditions, does hearing differ between men and women, are there "particularly outstanding" record holders who hear inaccessible sounds, or can produce them? Let's try to answer these and some other related questions in more detail.

But before you understand how many hertz he hears human ear, you need to understand such a fundamental concept as sound, and in general, understand what exactly is measured in hertz.

Sound vibrations are unique way transfer of energy without the transfer of matter, they are elastic oscillations in any medium. When it comes to ordinary life man, such a medium is air. It contains gas molecules that can transmit acoustic energy. This energy represents the alternation of bands of compression and tension of the density of the acoustic medium. In absolute vacuum, sound vibrations cannot be transmitted.

Any sound is a physical wave, and contains all the necessary wave characteristics. This is the frequency, amplitude, decay time, if we are talking about a damped free oscillation. Consider it on simple examples. Imagine, for example, the sound of the open G string on a violin when it is drawn with a bow. We can define the following characteristics:

quiet or loud. It is nothing but the amplitude, or power of the sound. More loud sound corresponds to a large amplitude of oscillations, and a quiet sound - a smaller one. A sound of greater strength can be heard at a greater distance from the place of origin;

sound duration. Everyone understands this, and everyone is able to distinguish the peals of a drum roll from the extended sound of a choral organ melody;

pitch, or frequency of a sound wave. It is this fundamental characteristic that helps us to distinguish "beeping" sounds from the bass register. If there were no frequency of sound, music would only be possible in the form of rhythm. Frequency is measured in hertz, and 1 hertz is equal to one oscillation per second;

timbre of sound. It depends on the admixture of additional acoustic vibrations - formant, but to explain it in simple words very easy: even with eyes closed we understand that it is the violin that sounds, and not the trombone, even if they have exactly the same characteristics listed above.

The timbre of sound can be compared with numerous taste shades. In total, we have bitter, sweet, sour and salty tastes, but these four characteristics are far from exhausting all kinds of taste sensations. The same thing happens with timbre.

Let us dwell in more detail on the height of the sound, since it is on this characteristic that the most hearing acuity and the range of perceived acoustic vibrations. What is the audio frequency range?

Hearing range in ideal conditions

Frequencies perceived by the human ear in the laboratory, or ideal conditions, are in a relatively wide band from 16 Hertz to 20,000 Hertz (20 kHz). Everything above and below - the human ear can not hear. It's about about infrasound and ultrasound. What it is?

infrasound

It cannot be heard, but the body can feel it, like the work of a large bass speaker - a subwoofer. These are infrasonic vibrations. Everyone knows very well that if you constantly weaken the bass string on the guitar, then, despite the continued vibrations, the sound disappears. But these vibrations can still be felt with the fingertips by touching the string.

Many internal organs of a person work in the infrasonic range: there is a contraction of the intestines, expansion and constriction of blood vessels, many biochemical reactions. A very strong infrasound can cause a severe morbid condition, even waves of panic terror, which is the basis of the infrasonic weapons.

Ultrasound

On the opposite side of the spectrum are very high sounds. If the sound has a frequency above 20 kilohertz, then it stops "beeping" and becomes inaudible to the human ear in principle. It becomes ultrasonic. Ultrasound has great application in the national economy, based on it ultrasound diagnostics. With the help of ultrasound, ships navigate the sea, bypassing icebergs and avoiding shallow water. Thanks to ultrasound, specialists find voids in all-metal structures, for example, in rails. Everyone saw how workers rolled a special flaw detection trolley along the rails, generating and receiving high-frequency acoustic vibrations. Ultrasound is used the bats to find an unmistakable path in the dark without bumping into cave walls, whales and dolphins.

It is known that with age, the ability to distinguish high-pitched sounds decreases, and children can hear them best. Modern research show that already at the age of 9-10 years, the range of hearing in children begins to gradually decrease, and in older people the audibility of high frequencies is much worse.

To hear how older people perceive music, you just need to use the multi-band equalizer in the player of your cell phone turn down one or two rows of high frequencies. The resulting uncomfortable "mumbling, like from a barrel," and will be a great illustration of how you yourself will hear after the age of 70 years.

in hearing loss important role plays malnutrition, drinking and smoking, postponing cholesterol plaques on the walls of blood vessels. ENT statistics - doctors claim that people with the first blood group more often and faster come to hearing loss than the rest. Approaches hearing loss overweight, endocrine pathology.

Hearing range under normal conditions

If we cut off the "marginal sections" of the sound spectrum, then for comfortable life not so much is available to a person: this is a range from 200 Hz to 4000 Hz, which almost completely corresponds to the range of the human voice, from deep basso-profundo to high coloratura soprano. However, even when comfortable conditions, a person's hearing is constantly deteriorating. Usually, the highest sensitivity and susceptibility in adults under the age of 40 is at the level of 3 kilohertz, and at the age of 60 years or more it drops to 1 kilohertz.

Hearing range for men and women

Currently, sexual segregation is not welcome, but men and women really perceive sound differently: women are able to hear better in the high range, and the age-related involution of sound in the high frequency region is slower, and men perceive high sounds somewhat worse. It would seem logical to assume that men hear better in the bass register, but this is not so. The perception of bass sounds in both men and women is almost the same.

But there is unique women on the "generation" of sounds. Thus, the voice range of the Peruvian singer Yma Sumac (almost five octaves) extended from the sound “si” of a large octave (123.5 Hz) to “la” of the fourth octave (3520 Hz). An example of her unique vocals can be found below.

At the same time, men and women have quite a big difference in the functioning of the speech apparatus. Women produce sounds from 120 to 400 hertz, and men from 80 to 150 Hz, according to the average data.

Various scales to indicate hearing range

At the beginning, we talked about the fact that pitch is not the only characteristic of sound. Therefore, there are different scales, according to different ranges. The sound heard by the human ear can be, for example, quiet and loud. The simplest and most acceptable clinical practice sound volume scale - one that measures the sound pressure perceived by the eardrum.

This scale is based on the smallest energy of sound vibration, which is capable of transforming into nerve impulse, and evoke a sound sensation. This is the threshold of auditory perception. The lower the perception threshold, the higher the sensitivity, and vice versa. Specialists distinguish between sound intensity, which is a physical parameter, and loudness, which is a subjective value. It is known that a sound of exactly the same intensity is perceived by a healthy person and a person with hearing loss as two different sounds, louder and quieter.

Everyone knows how in the ENT doctor's office the patient stands in a corner, turns away, and the doctor from the next corner checks the patient's perception of whispered speech, uttering separate numbers. This is the simplest example primary diagnosis hearing loss.

It is known that the barely perceptible breath of another person is 10 decibels (dB) of sound pressure intensity, a normal conversation in home environment corresponds to 50 dB, the howling of a fire siren is 100 dB, and a jet aircraft taking off near, near pain threshold- 120 decibels.

It may be surprising that the entire enormous intensity of sound vibrations fits on such a small scale, but this impression is deceptive. This is a logarithmic scale, and each successive step is 10 times more intense than the previous one. According to the same principle, a scale for assessing the intensity of earthquakes is built, where there are only 12 points.

The video made by AsapSCIENCE is a kind of age-related hearing loss test that will help you know the limits of your hearing.

Various sounds are played in the video, starting at 8000 Hz, which means you are not hearing impaired.

Then the frequency rises, and this indicates the age of your hearing, depending on when you stop hearing a certain sound.

So if you hear a frequency:

12,000 Hz - you are under 50 years old

15,000 Hz - you are under 40 years old

16,000 Hz - you are under 30 years old

17 000 – 18 000 – you are under 24 years old

19 000 – you are under 20 years old

If you want the test to be more accurate, you should set the video quality to 720p, or better 1080p, and listen with headphones.

Hearing test (video)

hearing loss

If you have heard all the sounds, you are most likely under 20 years old. The results depend on sensory receptors in your ear called hair cells which become damaged and degenerate over time.

This type of hearing loss is called sensorineural hearing loss. This disorder can be caused whole line infections, drugs and autoimmune diseases. The outer hair cells, which are tuned to pick up higher frequencies, usually die first, and so the effect of age-related hearing loss occurs, as demonstrated in this video.

Human hearing: interesting facts

1. Among healthy people frequency range that can be heard by the human ear ranges from 20 (lower than the lowest note on a piano) to 20,000 Hertz (higher than the highest note on a small flute). However, the upper limit of this range steadily decreases with age.

2. People talk to each other at a frequency of 200 to 8000 Hz, and the human ear is most sensitive to a frequency of 1000 - 3500 Hz

3. Sounds that are above the limit of human hearing are called ultrasound, and those below infrasound.

4. Our ears don't stop working even in sleep while continuing to hear sounds. However, our brain ignores them.

5. Sound travels at 344 meters per second. A sonic boom occurs when an object overcomes the speed of sound. Sound waves in front of and behind the object collide and create an impact.

6. Ears - self-cleaning organ. Pores in ear canal allocate earwax, and tiny hairs called cilia push wax out of the ear

7. The sound of a baby crying is approximately 115 dB and it's louder than a car horn.

8. In Africa, there is the Maaban tribe, who live in such silence that they are even in old age. hear whispers up to 300 meters away.

9. Level the sound of a bulldozer idle is about 85 dB (decibel), which can cause hearing damage after just one 8-hour work day.

10. Sitting in front speakers at a rock concert, you're exposing yourself to 120 dB, which starts damaging your hearing after just 7.5 minutes.

Everyone saw on audiograms or audio equipment such a volume parameter or associated with it -. This is a unit of measurement for loudness. Once upon a time, people agreed and denoted that normally a person hears from 0 dB, which actually means a certain sound pressure that is perceived by the ear. Statistics say that the normal range is both a slight drop to 20dB, and hearing above the norm in the form of -10dB! The delta of the "norm" is 30 dB, which is somehow quite a lot.

What is the dynamic range of hearing? This is the ability to hear sounds at different volumes. It is generally accepted as a fact that the human ear can hear from 0dB to 120-140dB. It is highly not recommended to listen to sounds already from 90dB and above for a long time.

The dynamic range of each ear tells us that at 0dB the ear hears well and in detail, at 50dB it hears well and in detail. You can do it at 100dB. In practice, everyone has been to a club or a concert where the music played loudly - and the detail is wonderful. We listened to the food, barely quietly through the headphones, lying in quiet room- and also all the details are in place.

In fact, hearing loss can be described as a reduction in dynamic range. In fact, a person with poor hearing cannot hear details at low volumes. Its dynamic range narrows. Instead of 130dB, it becomes 50-80dB. That is why: there is no way to "shove" information that in reality is in the 130dB range into the 80dB range. And if you also remember that decibels are a non-linear dependence, then the whole tragedy of the situation becomes clear.

But now let's remember good hearing. Here someone hears everything at a level of about 10 dB drop. This is normal and socially acceptable. In practice, such a person can hear ordinary speech from 10 meters. But then a man appears perfect hearing-- above 0 by 10 dB -- and he hears the same speech from 50 meters with equal conditions. The dynamic range is wider - there are more details and possibilities.

A wide dynamic range makes the brain work in a completely, qualitatively different way. Much more information, it is much more accurate and detailed, because. more and more different overtones and harmonics are heard, which disappear with a narrow dynamic range: they escape the attention of a person, because impossible to hear them.

By the way, since a dynamic range of 100dB+ is available, it also means that a person can constantly use it. I just listened at a volume level of 70dB, then abruptly began to listen - 20dB, then 100dB. The transition should take as little time as possible. And in fact, one can say that a person with a fall does not allow himself to have a large dynamic range. Deaf people seem to substitute the idea that everything is very loud now - and the ear is preparing to hear loud or very loud, instead of the real situation.

At the same time, the dynamic range by its presence shows that the ear not only records sounds, but also adjusts to the current volume in order to hear everything well. The overall volume parameter is transmitted to the brain in exactly the same way as sound signals.

But a person with perfect hearing can very flexibly vary his dynamic range. And in order to hear something, he does not tense up, but purely relaxes. Thus, the hearing remains excellent both in the dynamic range and at the same time in the frequency range.

Hearing test (video)

hearing loss

If you have heard all the sounds, you are most likely under 20 years old. The results depend on sensory receptors in your ear called hair cells which become damaged and degenerate over time.

This type of hearing loss is called sensorineural hearing loss. A range of infections, medications, and autoimmune diseases can cause this disorder. The outer hair cells, which are tuned to pick up higher frequencies, usually die first, and so the effect of age-related hearing loss occurs, as demonstrated in this video.

Human hearing: interesting facts

2. People talk to each other at a frequency of 200 to 8000 Hz, and the human ear is most sensitive to a frequency of 1000 - 3500 Hz

3. Sounds that are above the limit of human hearing are called ultrasound, and those below infrasound.

4. Our ears don't stop working even in sleep while continuing to hear sounds. However, our brain ignores them.

5. Sound travels at 344 meters per second. A sonic boom occurs when an object overcomes the speed of sound. Sound waves in front of and behind the object collide and create an impact.

6. Ears - self-cleaning organ. Pores in the ear canal secrete earwax, and tiny hairs called cilia push the wax out of the ear

7. The sound of a baby crying is approximately 115 dB and it's louder than a car horn.

8. In Africa, there is the Maaban tribe, who live in such silence that they are even in old age. hear whispers up to 300 meters away.

9. Level the sound of a bulldozer idle is about 85 dB (decibel), which can cause hearing damage after just one 8-hour work day.

10. Sitting in front speakers at a rock concert, you're exposing yourself to 120 dB, which starts damaging your hearing after just 7.5 minutes.

frequency range of hearing. Threshold of pain

Features of human perception. Hearing

sound waves

Organs of sound perception

Limits of Perception

Synesthesia

Conclusion

Hearing range in ideal conditions

infrasound

Ultrasound

Hearing range under normal conditions

Hearing range for men and women

Various scales to indicate hearing range

Hearing test (video)

hearing loss

Human hearing: interesting facts

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