The frequency range of the human ear. Human hearing: interesting facts

Audio topics worth talking about human hearing a little more. How subjective is our perception? Can you test your hearing? Today you will learn the easiest way to find out if your hearing is fully consistent with the table values.

It is known that the average person is able to perceive acoustic waves in the range from 16 to 20,000 Hz (16,000 Hz depending on the source). This range is called the audible range.

20 Hz	A hum that can only be felt but not heard. It is reproduced mainly by top-end audio systems, so in case of silence, it is she who is to blame
30 Hz	If you can't hear it, it's most likely a playback problem again.
40 Hz	It will be audible in budget and mainstream speakers. But very quiet
50 Hz	The roar of electric current. Must be heard
60 Hz	Audible (like everything up to 100 Hz, rather tangible due to reflection from the auditory canal) even through the cheapest headphones and speakers
100 Hz	End of bass. Beginning of the range of direct hearing
200 Hz	Mid frequencies
500 Hz
1 kHz
2 kHz
5 kHz	Beginning of the high frequency range
10 kHz	If this frequency is not audible, it is likely serious problems with hearing. Need a doctor's consultation
12 kHz	The inability to hear this frequency may indicate the initial stage of hearing loss.
15 kHz	A sound that some people over 60 can't hear
16 kHz	Unlike the previous one, almost all people over 60 do not hear this frequency.
17 kHz	Frequency is a problem for many already in middle age
18 kHz	Problems with the audibility of this frequency - the beginning age-related changes hearing. Now you are an adult. :)
19 kHz	Limit frequency of average hearing
20 kHz	Only children hear this frequency. Truth

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This test is enough for a rough estimate, but if you do not hear sounds above 15 kHz, then you should consult a doctor.

Please note that the low frequency audibility problem is most likely related to.

Most often, the inscription on the box in the style of "Reproducible range: 1–25,000 Hz" is not even marketing, but an outright lie on the part of the manufacturer.

Unfortunately, companies are not required to certify not all audio systems, so it is almost impossible to prove that this is a lie. Speakers or headphones, perhaps, reproduce the boundary frequencies ... The question is how and at what volume.

Spectrum problems above 15 kHz are quite a common age phenomenon that users are likely to encounter. But 20 kHz (the very ones that audiophiles are fighting for so much) are usually heard only by children under 8-10 years old.

It is enough to listen to all the files sequentially. For more detailed study you can play samples, starting with the minimum volume, gradually increasing it. This will allow you to get more correct result in the event that the hearing is already slightly damaged (recall that for the perception of some frequencies it is necessary to exceed a certain threshold value, which, as it were, opens, helps the hearing aid to hear it).

Do you hear all frequency range who is capable?

Hearing loss is a pathological condition characterized by hearing loss and difficulty in understanding spoken language. It occurs quite often, especially in the elderly. However, today there is a trend towards an earlier development of hearing loss, including among young people and children. Depending on how weakened hearing is, hearing loss is divided into different degrees.

What are decibels and hertz

Any sound or noise can be characterized by two parameters: height and sound intensity.

Pitch

The pitch of a sound is determined by the number of vibrations of the sound wave and is expressed in hertz (Hz): the higher the hertz, the higher the tone. For example, the very first white key on the left on a conventional piano (“A” subcontroctave) produces a low sound at 27.500 Hz, while the very last white key on the right (“up to” the fifth octave) produces 4186.0 Hz.

The human ear is able to distinguish sounds within the range of 16–20,000 Hz. Anything less than 16 Hz is called infrasound, and anything over 20,000 is called ultrasound. Both ultrasound and infrasound are not perceived by the human ear, but can affect the body and psyche.

All in frequency audible sounds can be divided into high, medium and low frequencies. Low-frequency sounds are up to 500 Hz, mid-frequency - within 500-10,000 Hz, high-frequency - all sounds with a frequency of more than 10,000 Hz. The human ear, with the same impact force, hears mid-frequency sounds better, which are perceived as louder. Accordingly, low- and high-frequency sounds are “heard” quieter, or even “stop sounding” altogether. In general, after 40–50 years, the upper limit of audibility of sounds decreases from 20,000 to 16,000 Hz.

sound power

If the ear is exposed to a very loud sound, the eardrum may rupture. In the picture below - a normal membrane, above - a membrane with a defect.

Any sound can affect the organ of hearing in different ways. It depends on its sound strength, or loudness, which is measured in decibels (dB).

Normal hearing is able to distinguish sounds ranging from 0 dB and above. When exposed to loud sound more than 120 dB.

The most comfortable human ear feels in the range up to 80-85 dB.

For comparison:

winter forest in calm weather - about 0 dB,
rustling of leaves in the forest, park - 20-30 dB,
ordinary colloquial speech, office work - 40-60 dB,
noise from the engine in the car - 70-80 dB,
loud screams - 85-90 dB,
thunder rolls - 100 dB,
a jackhammer at a distance of 1 meter from it - about 120 dB.

Degrees of hearing loss relative to loudness

The following degrees of hearing loss are usually distinguished:

Normal hearing - a person hears sounds in the range from 0 to 25 dB and above. He distinguishes the rustle of leaves, the singing of birds in the forest, the ticking wall clock etc.
Hearing loss:

I degree (mild) - a person begins to hear sounds from 26-40 dB.
II degree (moderate) - the threshold for the perception of sounds starts from 40–55 dB.
III degree (severe) - hears sounds from 56-70 dB.
IV degree (deep) - from 71–90 dB.

Deafness is a condition when a person cannot hear a sound louder than 90 dB.

An abbreviated version of the degrees of hearing loss:

Light degree - the ability to perceive sounds less than 50 dB. Man understands colloquial speech almost completely at a distance of more than 1 m.
Medium degree - the threshold for the perception of sounds begins at a volume of 50–70 dB. Communication with each other is difficult, because in this case a person hears speech well at a distance of up to 1 m.
Severe degree - more than 70 dB. Speech of normal intensity is no longer audible or unintelligible near the ear. You have to scream or use a special hearing aid.

In everyday practical life specialists can use another classification of hearing loss:

Normal hearing. A person hears conversational speech and whispers at a distance of more than 6 m.
Mild hearing loss. A person understands conversational speech from a distance of more than 6 m, but he hears a whisper no more than 3-6 meters away from him. The patient can distinguish speech even with extraneous noise.
Moderate degree of hearing loss. A whisper distinguishes at a distance of no more than 1-3 m, and ordinary conversational speech - up to 4-6 m. Speech perception can be disturbed by extraneous noise.
Significant degree of hearing loss. Conversational speech is heard no further than at a distance of 2-4 m, and a whisper - up to 0.5-1 m. There is an illegible perception of words, some individual phrases or words have to be repeated several times.
Severe degree. Whisper is almost indistinguishable even at the very ear, colloquial speech, even when screaming, is hardly distinguished at a distance of less than 2 m. Reads lips more.

Degrees of hearing loss relative to pitch

I group. Patients are able to perceive only low frequencies in the range of 125–150 Hz. They only respond to low and loud voices.
II group. In this case, higher frequencies become available for perception, which are in the range from 150 to 500 Hz. Usually, simple colloquial vowels "o", "y" become distinguishable for perception.
III group. Good perception of low and medium frequencies (up to 1000 Hz). Such patients already listen to music, distinguish the doorbell, hear almost all vowels, catch the meaning simple phrases and individual words.
IV group. Become accessible to the perception of frequencies up to 2000 Hz. Patients distinguish almost all sounds, as well as individual phrases and words. They understand speech.

This classification of hearing loss is important not only for correct selection hearing aid, but also the definition of children in a regular or specialized school for.

Diagnosis of hearing loss

Audiometry can help determine the degree of hearing loss in a patient.

The most accurate reliable way to identify and determine the degree of hearing loss is audiometry. For this purpose, the patient is put on special headphones, into which a signal of appropriate frequencies and strength is applied. If the subject hears a signal, then he lets know about it by pressing the button of the device or by nodding his head. According to the results of audiometry, a corresponding curve of auditory perception (audiogram) is built, the analysis of which allows not only to identify the degree of hearing loss, but also in some situations to get a more in-depth understanding of the nature of hearing loss.
Sometimes, when performing audiometry, they do not wear headphones, but use a tuning fork or simply pronounce certain words at some distance from the patient.

When to See a Doctor

It is necessary to contact an ENT doctor if:

You began to turn your head towards the one who is speaking, and at the same time strain to hear him.
Relatives living with you or friends who have come to visit make a remark about the fact that you turned on the TV, radio, player too loudly.
The doorbell is now not as clear as before, or you have stopped hearing it altogether.
When talking on the phone, you ask the other person to speak louder and more clearly.
They began to ask you to repeat what you were told again.
If there is noise around, then it becomes much more difficult to hear the interlocutor and understand what he is talking about.

Despite the fact that, in general, the earlier the correct diagnosis is established and treatment is started, the better results and topics more likely that the rumor will persist for many years to come.

Frequencies

Frequency - physical quantity, a characteristic of a periodic process, is equal to the number of repetitions or the occurrence of events (processes) per unit time.
As We know, the human ear hears frequencies from 16 Hz to 20,000 kHz. But it's very mediocre.
The sound comes from different reasons. Sound is the wavelike pressure of air. If there were no air, we would not hear any sound. There is no sound in space.
We hear sound because our ears are sensitive to changes in air pressure - sound waves. The simplest sound wave is a short sound signal - like this:
Sound waves entering the auditory canal vibrate eardrum. Through the chain of bones of the middle ear, the oscillatory movement of the membrane is transmitted to the fluid of the cochlea. The undulating motion of this fluid is in turn transmitted to the underlying membrane. The movement of the latter entails irritation of the endings of the auditory nerve. Such Main way sound from its source to our consciousness. TYTS

When you clap your hands, the air between your palms is pushed out and a sound wave is created. High blood pressure causes air molecules to spread in all directions at the speed of sound, which is 340 m/s. When the wave reaches the ear, it causes the eardrum to vibrate, from which the signal is transmitted to the brain and you hear a pop.
The clap is a short single oscillation that decays quickly. Schedule sound vibrations a typical cotton looks like this:
Another typical example of a simple sound wave is a periodic oscillation. For example, when a bell rings, the air is shaken by periodic vibrations of the walls of the bell.
So at what frequency does the normal human ear begin to hear? It will not hear a frequency of 1 Hz, but can only see it on the example of an oscillatory system. The human ear actually hears from frequencies of 16 Hz. That is, when air vibrations perceive our ear as a kind of sound.
How many sounds does a person hear?
Not all people with normal hearing hear the same way. Some are able to distinguish sounds close in pitch and volume and to pick up individual tones in music or noise. Others cannot do this. For a person with fine hearing, there are more sounds than for a person with undeveloped hearing.
But how different in general should the frequency of two sounds be in order to be heard as two different tones? Is it possible, for example, to distinguish tones from each other if the difference in frequencies is equal to one oscillation per second? It turns out that for some tones this is possible, but not for others. So, a tone with a frequency of 435 can be distinguished in height from tones with frequencies of 434 and 436. But if we take higher tones, then the difference is already at a greater frequency difference. Tones with a vibration number of 1000 and 1001 are perceived by the ear as the same and pick up the difference in sound only between frequencies 1000 and 1003. For higher tones, this difference in frequencies is even greater. For example, for frequencies around 3000 it is equal to 9 oscillations.
In the same way, our ability to distinguish sounds that are close in loudness is not the same. At a frequency of 32, only 3 sounds of different loudness can be heard; at a frequency of 125 there are already 94 sounds of different loudness, at 1000 vibrations - 374, at 8000 - again less and, finally, at a frequency of 16,000 we hear only 16 sounds. In total, sounds, different in height and loudness, our ear can catch more than half a million! It's only half a million simple sounds. Add to this countless combinations of two or more tones - consonance, and you will get an impression of the diversity of the sound world in which we live and in which our ear is so freely oriented. That is why the ear is considered, along with the eye, the most sensitive sense organ.
Therefore, for the convenience of understanding the sound, we use an unusual scale with divisions of 1 kHz.
And logarithmic. With extended frequency representation from 0 Hz to 1000 Hz. The frequency spectrum, therefore, can be represented as such a diagram from 16 to 20,000 Hz.
But not all people, even with normal hearing, are equally sensitive to sounds of different frequencies. So, children usually perceive sounds with a frequency of up to 22 thousand without tension. In most adults, the sensitivity of the ear to high-pitched sounds has already been reduced to 16-18 thousand vibrations per second. The sensitivity of the ear of the elderly is limited to sounds with a frequency of 10-12 thousand. They often do not hear the mosquito singing, the chirping of the grasshopper, the cricket, and even the chirping of the sparrow. Thus, from an ideal sound (fig. above), as a person ages, he already hears sounds in a narrower perspective
I will give an example of a frequency range musical instruments
Now for our topic. Dynamics, as an oscillatory system, due to a number of its features, cannot reproduce the entire frequency spectrum with constant linear characteristics. Ideally, this would be a full-range speaker that reproduces the frequency spectrum from 16 Hz to 20 kHz at one volume level. Therefore, several types of speakers are used in car audio to reproduce specific frequencies.
It looks like this conditionally so far (for a three-way system + subwoofer).
Subwoofer 16Hz to 60Hz
Midbass from 60 Hz to 600 Hz
Midrange from 600 Hz to 3000 Hz
Tweeter from 3000 Hz to 20000 Hz

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. 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

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. The pores in the ear canal secrete 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.

Psychoacoustics - a field of science bordering between physics and psychology, studies data on the auditory sensation of a person when a physical stimulus - sound - acts on the ear. A large amount of data has been accumulated on human reactions to auditory stimuli. Without this data, it is difficult to gain a correct understanding of the operation of audio frequency signaling systems. Consider the most important features of human perception of sound.
A person feels changes in sound pressure occurring at a frequency of 20-20,000 Hz. Sounds below 40 Hz are relatively rare in music and do not exist in spoken language. At very high frequencies, musical perception disappears and a certain indefinite sound sensation arises, depending on the individuality of the listener, his age. With age, the sensitivity of hearing in humans decreases, especially in the upper frequencies of the sound range.
But it would be wrong to conclude on this basis that the transmission of a wide frequency band by a sound reproducing installation is unimportant for older people. Experiments have shown that people, even barely perceiving signals above 12 kHz, very easily recognize the lack of high frequencies in a musical transmission.

Frequency characteristics of auditory sensations

The area of sounds audible by a person in the range of 20-20000 Hz is limited in intensity by thresholds: from below - audibility and from above - pain.
The hearing threshold is estimated by the minimum pressure, more precisely, by the minimum increase in pressure relative to the boundary, it is sensitive to frequencies of 1000-5000 Hz - here the hearing threshold is the lowest (sound pressure is about 2-10 Pa). In the direction of lower and higher sound frequencies, the sensitivity of hearing drops sharply.
The pain threshold determines the upper limit of the perception of sound energy and corresponds approximately to a sound intensity of 10 W / m or 130 dB (for a reference signal with a frequency of 1000 Hz).
With an increase in sound pressure, the intensity of the sound also increases, and the auditory sensation increases in jumps, called the intensity discrimination threshold. The number of these jumps at medium frequencies is about 250, at low and high frequencies it decreases and, on average, over the frequency range is about 150.

Since the range of intensity variation is 130 dB, then the elementary jump of sensations on average over the amplitude range is 0.8 dB, which corresponds to a change in sound intensity by 1.2 times. At low levels hearing, these jumps reach 2-3 dB, at high levels they decrease to 0.5 dB (1.1 times). An increase in the power of the amplifying path by less than 1.44 times is practically not fixed by the human ear. With a lower sound pressure developed by the loudspeaker, even a twofold increase in the power of the output stage may not give a tangible result.

Subjective characteristics of sound

The quality of sound transmission is evaluated on the basis of auditory perception. Therefore, it is possible to correctly determine the technical requirements for the sound transmission path or its individual links only by studying the patterns that connect the subjectively perceived sensation of sound and the objective characteristics of sound are pitch, loudness and timbre.
The concept of pitch implies a subjective assessment of the perception of sound in the frequency range. Sound is usually characterized not by frequency, but by pitch.
Tone is a signal of a certain height, having a discrete spectrum (musical sounds, vowels of speech). A signal that has a wide continuous spectrum, all frequency components of which have the same average power, is called white noise.

A gradual increase in the frequency of sound vibrations from 20 to 20,000 Hz is perceived as a gradual change in tone from the lowest (bass) to the highest.
The degree of accuracy with which a person determines the pitch by ear depends on the sharpness, musicality and training of his ear. It should be noted that the pitch depends to some extent on the intensity of the sound (at high levels, sounds of greater intensity appear lower than weaker ones..
The human ear is good at distinguishing two tones that are close in pitch. For example, in the frequency range of approximately 2000 Hz, a person can distinguish between two tones that differ from each other in frequency by 3-6 Hz.
The subjective scale of sound perception in terms of frequency is close to the logarithmic law. Therefore, a doubling of the oscillation frequency (regardless of the initial frequency) is always perceived as the same change in pitch. The pitch interval corresponding to a frequency change of 2 times is called an octave. The frequency range perceived by a person is 20-20,000 Hz, it covers approximately ten octaves.
An octave is a fairly large pitch change interval; a person distinguishes much smaller intervals. So, in ten octaves perceived by the ear, one can distinguish more than a thousand gradations of pitch. Music uses smaller intervals called semitones, which correspond to a frequency change of approximately 1.054 times.
An octave is divided into half octaves and a third of an octave. For the latter, the following range of frequencies has been standardized: 1; 1.25; 1.6; 2; 2.5; 3; 3.15; four; 5; 6.3:8; 10, which are the boundaries of one-third octaves. If these frequencies are placed at equal distances along the frequency axis, then a logarithmic scale will be obtained. Based on this, all frequency characteristics of sound transmission devices are built on a logarithmic scale.
The transmission loudness depends not only on the intensity of the sound, but also on the spectral composition, the conditions of perception and the duration of exposure. So, two sounding tones of middle and low frequency having the same intensity (or the same sound pressure) are not perceived by a person as equally loud. Therefore, the concept of loudness level in backgrounds was introduced to denote sounds of the same loudness. The level of sound pressure in decibels of the same volume of a pure tone with a frequency of 1000 Hz is taken as the sound volume level in phons, i.e. for a frequency of 1000 Hz, the volume levels in phons and decibels are the same. At other frequencies, for the same sound pressure, sounds may appear louder or quieter.
The experience of sound engineers in recording and editing musical works shows that in order to better detect sound defects that may occur during work, the volume level during control listening should be kept high, approximately corresponding to the volume level in the hall.
With prolonged exposure to intense sound, hearing sensitivity gradually decreases, and the more, the higher the volume of the sound. The detectable reduction in sensitivity is related to the hearing response to overload, i.e. with its natural adaptation, After a break in listening, hearing sensitivity is restored. To this it should be added that the hearing aid, when perceiving high-level signals, introduces its own, so-called subjective, distortions (which indicates the non-linearity of hearing). Thus, at a signal level of 100 dB, the first and second subjective harmonics reach levels of 85 and 70 dB.
A significant volume level and the duration of its exposure cause irreversible effects in auditory organ. It has been noted that young people last years hearing thresholds increased sharply. The reason for this was the passion for pop music, which is different high levels sound volume.
The volume level is measured using an electro-acoustic device - a sound level meter. The measured sound is first converted by the microphone into electrical vibrations. After amplification by a special voltage amplifier, these oscillations are measured with a pointer device adjusted in decibels. To ensure that the readings of the device correspond as closely as possible to the subjective perception of loudness, the device is equipped with special filters that change its sensitivity to sound perception. different frequencies according to the characteristic of hearing sensitivity.
An important characteristic of sound is timbre. The ability of hearing to distinguish it allows you to perceive signals with a wide variety of shades. The sound of each of the instruments and voices, due to their characteristic shades, becomes multicolored and well recognizable.
Timbre, being a subjective reflection of the complexity of the perceived sound, does not have a quantitative assessment and is characterized by terms of a qualitative order (beautiful, soft, juicy, etc.). When a signal is transmitted through an electro-acoustic path, the resulting distortions primarily affect the timbre of the reproduced sound. The condition for the correct transmission of the timbre of musical sounds is the undistorted transmission of the signal spectrum. The signal spectrum is a set of sinusoidal components of a complex sound.
The so-called pure tone has the simplest spectrum, it contains only one frequency. The sound of a musical instrument turns out to be more interesting: its spectrum consists of the fundamental frequency and several "impurity" frequencies, called overtones (higher tones). Overtones are multiples of the fundamental frequency and are usually smaller in amplitude.
The timbre of the sound depends on the distribution of intensity over the overtones. The sounds of different musical instruments differ in timbre.
More complex is the spectrum of combination of musical sounds, called a chord. In such a spectrum, there are several fundamental frequencies along with the corresponding overtones.
Differences in timbre are shared mainly by the low-mid frequency components of the signal, therefore, a large variety of timbres is associated with signals lying in the lower part of the frequency range. The signals related to its upper part, as they increase, lose their timbre coloring more and more, which is due to the gradual departure of their harmonic components beyond audible frequencies. This can be explained by the fact that up to 20 or more harmonics are actively involved in the formation of the timbre of low sounds, medium 8 - 10, high 2 - 3, since the rest are either weak or fall out of the region of audible frequencies. Therefore, high sounds, as a rule, are poorer in timbre.
Almost all natural sound sources, including sources of musical sounds, have a specific dependence of the timbre on the volume level. Hearing is also adapted to such a dependence - for it it is natural definition intensity of the source according to the color of the sound. Loud sounds are usually more harsh.

Musical sound sources

Big influence on the sound quality of electroacoustic systems a number of factors characterizing the primary sources of sounds.
The acoustic parameters of musical sources depend on the composition of the performers (orchestra, ensemble, group, soloist and type of music: symphonic, folk, pop, etc.).

The origin and formation of sound on each musical instrument has its own specifics associated with the acoustic features of sound formation in a particular musical instrument.
An important element musical sound is attack. This is a specific transient process during which stable sound characteristics are established: loudness, timbre, pitch. Any musical sound goes through three stages - beginning, middle and end, and both the initial and final stages have a certain duration. initial stage called an attack. It lasts differently: for plucked, percussion and some wind instruments 0-20 ms, for bassoon 20-60 ms. An attack is not just an increase in sound volume from zero to some steady value, it can be accompanied by the same change in pitch and timbre. Moreover, the attack characteristics of the instrument are not the same in different areas its range with a different style of playing: the violin, in terms of the richness of possible expressive methods of attack, is the most perfect instrument.
One of the characteristics of any musical instrument is the frequency range of the sound. In addition to the fundamental frequencies, each instrument is characterized by additional high-quality components - overtones (or, as is customary in electroacoustics, higher harmonics), which determine its specific timbre.
It is known that sound energy is unevenly distributed over the entire spectrum of sound frequencies emitted by the source.
Most instruments are characterized by amplification of the fundamental frequencies, as well as individual overtones in certain (one or more) relatively narrow frequency bands (formants), which are different for each instrument. The resonant frequencies (in hertz) of the formant region are: for trumpet 100-200, horn 200-400, trombone 300-900, trumpet 800-1750, saxophone 350-900, oboe 800-1500, bassoon 300-900, clarinet 250-600 .
Another characteristic property of musical instruments is the strength of their sound, which is determined by a larger or smaller amplitude (span) of their sounding body or air column (a larger amplitude corresponds to a stronger sound and vice versa). The value of peak acoustic powers (in watts) is: for large orchestra 70, bass drum 25, timpani 20, snare drum 12, trombone 6, piano 0.4, trumpet and saxophone 0.3, trumpet 0.2, double bass 0.( 6, piccolo 0.08, clarinet, horn and triangle 0.05.
The ratio of the sound power extracted from the instrument when performing "fortissimo" to the sound power when performing "pianissimo" is commonly called the dynamic range of the sound of musical instruments.
The dynamic range of a musical sound source depends on the type of performing group and the nature of the performance.
Consider dynamic range individual sound sources. Under the dynamic range of individual musical instruments and ensembles (orchestras and choirs of various composition), as well as voices, we understand the ratio of the maximum sound pressure created by a given source to the minimum, expressed in decibels.
In practice, when determining the dynamic range of a sound source, one usually operates only with sound pressure levels, calculating or measuring their corresponding difference. For example, if the maximum sound level of an orchestra is 90 and the minimum is 50 dB, then the dynamic range is said to be 90 - 50 = = 40 dB. In this case, 90 and 50 dB are the sound pressure levels relative to the zero acoustic level.
The dynamic range for a given sound source is not constant. It depends on the nature of the performed work and on the acoustic conditions of the room in which the performance takes place. Reverb expands the dynamic range, which usually reaches its maximum value in rooms with a large volume and minimal sound absorption. Almost all instruments and human voices have a dynamic range that is uneven across the sound registers. For example, the volume level of the lowest sound on the "forte" of the vocalist is equal to the level of the highest sound on the "piano".

The dynamic range of a particular musical program is expressed in the same way as for individual sound sources, but the maximum sound pressure is noted with a dynamic ff (fortissimo) shade, and the minimum with pp (pianissimo).

The highest volume, indicated in notes fff (forte, fortissimo), corresponds to an acoustic sound pressure level of approximately 110 dB, and the lowest volume, indicated in notes prr (piano-pianissimo), approximately 40 dB.
It should be noted that the dynamic shades of performance in music are relative and their connection with the corresponding sound pressure levels is to some extent conditional. The dynamic range of a particular musical program depends on the nature of the composition. Thus, the dynamic range of classical works by Haydn, Mozart, Vivaldi rarely exceeds 30-35 dB. The dynamic range of variety music usually does not exceed 40 dB, while dance and jazz - only about 20 dB. Most works for Russian folk instruments orchestra also have a small dynamic range (25-30 dB). This is true for the brass band as well. However, the maximum sound level of a brass band in a room can reach a fairly high level (up to 110 dB).

masking effect

The subjective assessment of loudness depends on the conditions in which the sound is perceived by the listener. AT real conditions the acoustic signal does not exist in absolute silence. At the same time, extraneous noises affect the hearing, making it difficult sound perception, masking to a certain extent the main signal. The effect of masking a pure sinusoidal tone by extraneous noise is estimated by a value indicating. by how many decibels the threshold of audibility of the masked signal rises above the threshold of its perception in silence.
Experiments to determine the degree of masking of one sound signal by another show that the tone of any frequency is masked by lower tones much more effectively than by higher ones. For example, if two tuning forks (1200 and 440 Hz) emit sounds with the same intensity, then we stop hearing the first tone, it is masked by the second one (having extinguished the vibration of the second tuning fork, we will hear the first one again).
If there are two complex sound signal, consisting of certain spectra of sound frequencies, then the effect of mutual masking occurs. Moreover, if the main energy of both signals lies in the same region of the audio frequency range, then the masking effect will be the strongest. Thus, when transmitting an orchestral work, due to masking by the accompaniment, the soloist's part may become poorly legible, indistinct.
Achieving clarity or, as they say, "transparency" of sound in the sound transmission of orchestras or pop ensembles becomes very difficult if the instrument or individual groups of instruments of the orchestra play in the same or close registers at the same time.
When recording an orchestra, the director must take into account the peculiarities of disguise. At rehearsals, with the help of a conductor, he sets a balance between the sound power of the instruments of one group, as well as between the groups of the entire orchestra. The clarity of the main melodic lines and individual musical parts is achieved in these cases by the close location of the microphones to the performers, the deliberate selection by the sound engineer of the most important instruments in a given place, and other special sound engineering techniques.
The phenomenon of masking is opposed by the psycho-physiological ability of the hearing organs to single out one or more sounds from the general mass that carry the most important information. For example, when the orchestra is playing, the conductor notices the slightest inaccuracies in the performance of the part on any instrument.
Masking can significantly affect the quality of signal transmission. A clear perception of the received sound is possible if its intensity significantly exceeds the level of interference components that are in the same band as the received sound. With uniform interference, the signal excess should be 10-15 dB. This feature of auditory perception is practical use, for example, when evaluating the electroacoustic characteristics of carriers. So, if the signal-to-noise ratio of an analog record is 60 dB, then the dynamic range of the recorded program can be no more than 45-48 dB.

Temporal characteristics of auditory perception

Hearing aid, like any other oscillatory system, is inertial. When the sound disappears, the auditory sensation does not disappear immediately, but gradually, decreasing to zero. The time during which the sensation in terms of loudness decreases by 8-10 phon is called the hearing time constant. This constant depends on a number of circumstances, as well as on the parameters of the perceived sound. If two short sound pulses arrive at the listener with the same frequency composition and level, but one of them is delayed, then they will be perceived together with a delay not exceeding 50 ms. For large delay intervals, both pulses are perceived separately, an echo occurs.
This feature of hearing is taken into account when designing some signal processing devices, for example, electronic delay lines, reverbs, etc.
It should be noted that due to the special property of hearing, the perception of the volume of a short-term sound impulse depends not only on its level, but also on the duration of the impact of the impulse on the ear. So, a short-term sound, lasting only 10-12 ms, is perceived by the ear quieter than a sound of the same level, but affecting the ear for, for example, 150-400 ms. Therefore, when listening to a transmission, the loudness is the result of averaging the energy of the sound wave over a certain interval. In addition, human hearing has inertia, in particular, when perceiving non-linear distortions, he does not feel such if the duration of the sound pulse is less than 10-20 ms. That is why in the level indicators of a sound recording household radio electronic equipment the instantaneous signal values are averaged over a period selected in accordance with the temporal characteristics of the hearing organs.

Spatial representation of sound

One of the important human abilities is the ability to determine the direction of the sound source. This ability is called the binaural effect and is explained by the fact that a person has two ears. Experimental data shows where the sound comes from: one for high-frequency tones, the other for low-frequency ones.

The sound travels a shorter path to the ear facing the source than to the second ear. As a result, the pressure of sound waves in ear canals differs in phase and amplitude. Amplitude differences are significant only at high frequencies, when the sound wave length becomes comparable to the size of the head. When the amplitude difference exceeds the 1 dB threshold, the sound source appears to be on the side where the amplitude is greater. The angle of deviation of the sound source from the center line (line of symmetry) is approximately proportional to the logarithm of the amplitude ratio.
To determine the direction of the sound source with frequencies below 1500-2000 Hz, phase differences are significant. It seems to a person that the sound comes from the side from which the wave, which is ahead in phase, reaches the ear. The angle of deviation of sound from the midline is proportional to the difference in the time of arrival of sound waves to both ears. A trained person can notice a phase difference with a time difference of 100 ms.
The ability to determine the direction of sound in the vertical plane is much less developed (about 10 times). This feature of physiology is associated with the orientation of the hearing organs in the horizontal plane.
Specific feature spatial perception of sound by a person is manifested in the fact that the hearing organs are able to feel the total, integral localization created with the help of artificial means of influence. For example, two speakers are installed in a room along the front at a distance of 2-3 m from each other. At the same distance from the axis of the connecting system, the listener is located strictly in the center. In the room, two sounds of the same phase, frequency and intensity are emitted through the speakers. As a result of the identity of the sounds passing into the organ of hearing, a person cannot separate them, his sensations give an idea of a single, apparent (virtual) sound source, which is located strictly in the center on the axis of symmetry.
If we now reduce the volume of one speaker, then the apparent source will move towards the louder speaker. The illusion of sound source movement can be obtained not only by changing the signal level, but also by artificially delaying one sound relative to another; in this case, the apparent source will shift towards the speaker, which emits a signal ahead of time.
Let us give an example to illustrate integral localization. The distance between speakers is 2m, the distance from the front line to the listener is 2m; in order for the source to shift as if by 40 cm to the left or right, it is necessary to apply two signals with a difference in intensity level of 5 dB or with a time delay of 0.3 ms. With a level difference of 10 dB or a time delay of 0.6 ms, the source will "move" 70 cm from the center.
Thus, if you change the sound pressure generated by the speakers, then the illusion of moving the sound source arises. This phenomenon is called total localization. To create a total localization, a two-channel stereophonic sound transmission system is used.
Two microphones are installed in the primary room, each of which works on its own channel. In the secondary - two loudspeakers. Microphones are located at a certain distance from each other along a line parallel to the placement of the sound emitter. When the sound emitter is moved, different sound pressure will act on the microphone and the arrival time of the sound wave will be different due to the unequal distance between the sound emitter and the microphones. This difference creates the effect of total localization in the secondary room, as a result of which the apparent source is localized in a certain point in space between two speakers.
It should be said about the binoural sound transmission system. With this system, called the "artificial head" system, two separate microphones are placed in the primary room, positioned at a distance from each other equal to the distance between the ears of a person. Each of the microphones has an independent sound transmission channel, at the output of which telephones for the left and right ears are switched on in the secondary room. With identical sound transmission channels, such a system accurately reproduces the binaural effect created near the ears of the "artificial head" in the primary room. The presence of headphones and the need to use them for a long time is a disadvantage.
The organ of hearing determines the distance to the source of sound in a row indirect signs and with some errors. Depending on whether the distance to the signal source is small or large, its subjective assessment changes under the influence of various factors. It was found that if the determined distances are small (up to 3 m), then their subjective assessment is almost linearly related to the change in the volume of the sound source moving along the depth. An additional factor for a complex signal is its timbre, which becomes more and more "heavy" "as the source approaches the listener. This is due to the increasing strengthening of the overtones of the low compared to the overtones of the high register, caused by the resulting increase in volume level.
For average distances of 3-10 m, the removal of the source from the listener will be accompanied by a proportional decrease in volume, and this change will equally apply to the fundamental frequency and to the harmonic components. As a result, there is a relative amplification of the high-frequency part of the spectrum and the timbre becomes brighter.
As the distance increases, the energy loss in the air will increase in proportion to the square of the frequency. Increased loss of high register overtones will result in a reduction in timbre brightness. Thus, the subjective assessment of distances is associated with a change in its volume and timbre.
In conditions enclosed space the signals of the first reflections, delayed by 20-40 ms relative to the direct one, are perceived by the ear as coming from different directions. At the same time, their increasing delay creates the impression of a significant distance from the points from which these reflections originate. Thus, according to the delay time, one can judge the relative remoteness of secondary sources or, which is the same, the size of the room.

Some features of the subjective perception of stereo broadcasts.

A stereophonic sound transmission system has a number of significant features compared to a conventional monophonic one.
The quality that distinguishes stereophonic sound, surround, i.e. natural acoustic perspective can be assessed using some additional indicators that do not make sense with a monophonic sound transmission technique. These additional indicators include: the angle of hearing, i.e. the angle at which the listener perceives the sound stereo image; stereo resolution, i.e. subjectively determined localization of individual elements of the sound image at certain points in space within the angle of audibility; acoustic atmosphere, i.e. the effect of making the listener feel present in the primary room where the transmitted sound event occurs.

About the role of room acoustics

The brilliance of sound is achieved not only with the help of sound reproduction equipment. Even with good enough equipment, the sound quality can be poor if the listening room does not have certain properties. It is known that in a closed room there is a phenomenon of over-sounding, called reverberation. By affecting the hearing organs, reverberation (depending on its duration) can improve or degrade the sound quality.

A person in the room perceives not only direct sound waves created directly by the sound source, but also waves reflected by the ceiling and walls of the room. Reflected waves are still audible for some time after the termination of the sound source.
It is sometimes believed that reflected signals play only a negative role, interfering with the perception of the main signal. However, this view is incorrect. certain part The energy of the initial reflected echo signals, reaching the ears of a person with short delays, amplifies the main signal and enriches its sound. On the contrary, later reflected echoes. the delay time of which exceeds a certain critical value, form a sound background that makes it difficult to perceive the main signal.
The listening room should not have a long reverberation time. Living rooms tend to have low reverberation due to their limited size and the presence of sound-absorbing surfaces, upholstered furniture, carpets, curtains, etc.
Barriers of different nature and properties are characterized by the sound absorption coefficient, which is the ratio of the absorbed energy to full energy incident sound wave.

To increase the sound-absorbing properties of the carpet (and reduce noise in the living room), it is advisable to hang the carpet not close to the wall, but with a gap of 30-50 mm).