It is called harmonic analysis of sound. Sound analysis

Decomposition of a complex sound into a series of simple waves. There are 2 types of sound analysis: frequency based on the frequencies of its harmonic components, and temporal, based on the study of signal changes over time ... Big Encyclopedic Dictionary

sound analysis- garso analizė statusas T sritis automatika atitikmenys: engl. sound analysis vok. Schallanalyse, f rus. sound analysis, m pranc. analyse de son, f … Automatikos terminų žodynas

sound analysis- garso analizė statusas T sritis fizika atitikmenys: angl. sound analysis vok. Schallanalyse, f rus. sound analysis, m pranc. analyse de son, f … Fizikos terminų žodynas

Decomposition of a complex sound into a series of simple waves. There are 2 types of A. z .: frequency according to the frequencies of its harmony, components, and temporal, main. on the study of signal changes over time ... Natural science. encyclopedic Dictionary

Decomposition of a complex sound. process into a series of simple vibrations. Two types of zoning are used: frequency and temporal. With frequency Z. a. sound. the signal is represented by the sum of harmonic. components characterized by frequency, phase and amplitude. ... ... Physical Encyclopedia

Decomposition of a complex sound process into a series of simple oscillations. Two types of sounding are used: frequency and time. With frequency Z. a. the sound signal is represented by the sum of the harmonic components (see Harmonic oscillations) ... Great Soviet Encyclopedia

ANALYSIS- 1) Make a. sound through hearing means to distinguish in a separate tone (consonance) of our music. instruments contained in it partial tones. The sum of vibrations, generating consonance, and composed of various single vibrations, our ear ... ... Riemann's musical dictionary

analysis of the syllabic structure of a word- This type of analysis L.L. Kasatkin recommends carrying out according to the following scheme: 1) give a phonetic transcription of the word, indicating syllabic consonants and non-syllabic vowels; 2) build a wave of sonority of the word; 3) under the letters of transcription in numbers ... ... Dictionary of linguistic terms T.V. Foal

The phenomenon of the irreversible transition of the energy of a sound wave into other forms of energy and, in particular, into heat. The coefficient is characterized absorption a, which is defined as the reciprocal of the distance, on krom the amplitude of the sound wave decreases in e \u003d 2.718 ... ... Physical Encyclopedia

Books

Modern Russian language. Theory. Analysis of language units. In 2 parts. Part 2. Morphology. Syntax , . The textbook was created in accordance with the Federal State Educational Standard in the direction of preparation 050100 - Pedagogical Education (profiles "Russian language" and "literature", ...
From sound to letter. Sound-letter analysis of words. Workbook for children 5-7 years old. Federal State Educational Standard, Durova Irina Viktorovna. Workbook`From sound to letter. The sound-letter analysis of words is included in the educational and methodological kit Teaching preschoolers to read. Designed for classes with older and preparatory children ...

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Task 20 No. 44. The electric tri-che arc is

A. from the beam of light by electro-da-mi, connected to a current source.

B. electric tri-che-sky raz-series in gas.

Correct answer

1) only A

2) only B

4) neither A nor B

Electric arc

Electric-tri-che-sky arc is one of the types of gas-zo-th-time-series-yes. You can get it in the following way. In the state-ti-ve, two carbon rods are fastened with pointed ends to each other and connected to a current source . When the coals come into co-adjac-but-ve-nie, and then slightly move-a-th, between the ends of the coals, a bright flame, and the coals themselves are dis-ka-la-ut-sya to-be-la. The arc burns steadily if a hundred-year-old electric current passes through it. In this case, one electrode is all the time in the lo-zhi-tel-nym (anode), and the other is from-ri-tsa-tel-nym (cathode). Between the electrics, there is a column of red-hot gas, ho-ro-sho about the electric power. Po-lo-zhi-tel-ny coal, having a higher te-pe-ra-tu-ru, burns faster, and deepens in it -le-nie - in-lo-zhi-tel-ny kra-ter. Tem-pe-ra-tu-ra kra-te-ra in the air-du-he at at-mo-spheral pressure up to 4000 ° C.

The arc can also burn between metal-li-che-ski-mi electro-tro-da-mi. At the same time, the electrodes are melting and quickly is-pa-rya-ut-sya, on which a lot of energy is dissipated. Therefore, the-pe-ra-tu-ra kra-te-ra metal-li-che-sko-go-electro-tro-yes is usually lower than coal-no-go (2,000— 2500 °С). When the arc burns in the gas at high pressure (about 2 10 6 Pa), the temp-pe-ra-tu-ru kra-te-ra managed to reach up to 5,900 ° C, i.e., up to the temperature on the top of the Sun. A column of gases or vapors, through which there is a discharge, has an even higher temperature - up to 6,000-7,000 ° C. Therefore, in the column, the arcs float and turn into steam almost all of the known substances.

To maintain the du-th-in-th-time-series-yes, you need not-big-voltage, the arc burns when the voltage is on its electric dax 40 V. The current strength in the arc is quite significant, but co-op-le-no-no; next-to-va-tel-but, luminous gas pole ho-ro-sho conducts electric current. Ioni-for-the-tion of gas molecules in the space between the el-tro-da-m you-y-y-yut with your pus-ka-e-mye ka-the-house of the arc. A large number of is-pus-ka-e-my-el-tro-news is ensured by the fact that the cathode is heated to a very high temperature -pe-ra-tu-ry. When, for za-zh-ga-niya arc vna-cha-le, coals are brought into co-at-kos-but-ve-nie, then in the place of con-so-ta, ob-la-da-yu -scheme is a very large co-op-tiv-le-ni-em, you-de-la-is-a huge amount of heat-lo-you. In this way, the ends of the coals strongly heat up, and this is enough to ensure that when they move apart, a well-la arc flashes between them . In the future, the cathode of the arc is kept in a heated state by the current itself, passing through the arc.

Task 20 No. 71. Gar-mo-ni-che-skim ana-li-zom of sound na-zy-va-yut

A. setting the number of tones included in the composition of a complex sound.

B. setting the frequencies and amplitudes of the tones that are part of the complex sound.

Correct answer:

1) only A

2) only B

4) neither A nor B

Sound analysis

With the help of the na-bo-ditch of the aku-sti-che-sky re-zo-to-the-ditch, you can find out which tones are included in the composition of the given sound and ka-ko-you am-pli-tu-dy. Such a set-up of the spectrum of a complex sound on-zy-va-et-sya with its gar-mo-no-che-ana-li-zom.

Previously, the analysis of sound was filled with the help of re-zo-on-to-ditch, representing hollow balls of different times -ra, having an open-cut from-ro-drain, inserting-la-e-my into the ear, and a hole with a pro-ty-in-false hundred-ro -us. For ana-li-behind the sound, it is essential that every time when the ana-li-zi-ru-e-my sound contains a tone, often a hundred -to-ro-go is equal to often re-zo-to-to-ra, the next-to-chi-na-to sound loudly in this tone.

Such ways of ana-li-za, one-on-one, very inaccurate and cro-pot-whether you. At the present time, they are you-tes-not-us, but more perfect-shen-us-mi, accurate-us-mi and fast-ry-mi-electro-tro- aku-sti-che-ski-mi me-to-da-mi. Their essence boils down to the fact that the acu-sti-che-ko-le-ba-sleep-cha-la is pre-ob-ra-zu-et-sya into an electric tri-che-ko -le-ba-nie with keeping the same shape, and consequently, having the same spectrum, and then this co-le-ba-nie ana-li-zi-ru-et-sya electric-tri-che-ski-mi me-to-da-mi.

One of the essential results of gar-mo-no-che-so-ana-li-for ka-sa-et-sya sounds of our speech. By the timbre, we can recognize the voice of a man-lo-ve-ka. But what is the difference between the sounds of ko-le-ba-niya when the same person sings different vowels on the same note? Other words-va-mi, than different-whether-cha-yut-sya in these cases, per-ri-o-di-che-ko-le-ba-niya air-du- ha, you-zy-va-e-my go-lo-so-ym app-pa-ra-tom with different lips and tongue and from me-no-no- yah forms according to the mouth and pharynx? Obviously, in the spectra of vowels there must be some kind of special ben-no-sti, characteristic for each vowel sound, beyond those especially-ben-no-stey, someone creates the timbre of go-lo-sa dan-no-go-lo-ve-ka. Gar-mo-ni-che-ana-lysis of vowels confirms this pre-position, namely: vowel sounds ha-rak-te-ri- zu-ut-sya on-li-chi-em in their spectra of ob-la-stey ober-to-new with a large am-pli-tu-doy, and these areas lie for each do vowel always on the same frequencies not-for-vi-si-mo from you-with-you about-ne-that-voice-no-th sound.

Assignment 20 No. 98. In the mass spec-tro-gra-fe

1) electric and magnetic fields serve to accelerate the charging of the charged part

2) electric and magnetic fields serve to change the direction of the movement of the charged part tsy

3) the electric field serves to accelerate the charge of the female part, and the magnetic field serves to change on-the-right-le-niya of her movement

4) the electric field serves to change the movement of the right-of-the-wife part, and the magnet field serves to speed it up

mass spectro graph

A mass spectro-graph is a device for separating ions in terms of magnitude from their order to mass. In the simplest mo-di-fi-ka-tion, the scheme of pri-bo-ra is presented-by-le-na on ri-sun-ke.

Is-follow-du-e-my sample of sp-tsi-al-ny-mi me-to-da-mi (is-pa-re-ni-em, electronic strike-rum) re-re-in-dit-sya into a gas-o-ob-different co-sto-i-tion, then form-ra-zo-vav-shi-sya gas ioni-zi-ru-et-sya into source 1. Then the ions are accelerated by an electric field and form-mi-ru-ut-sya into a narrow beam in an accelerating device 2, after which, through a narrow entrance slot, they are pa-da-yut in chamber 3, in some kind of co-building, but one-native magnetic field. The magnetic field from-me-is-it is a tra-ek-to-ryu of the movement of particles. Under the action of the force of Lo-ren-ts, the ions on-chi-na-yut move along the arc of the circle and go to screen 4, where re-gi-stri -ru-et-xia place them in-pa-da-niya. Methods of re-gi-stra-tion can be different: photo-graphic-fi-che-sky, electronic, etc. Ra-di-ustra -ek-to-ri opre-de-la-et-xia according to the form-mu-le:

where U- electric voltage of the accelerating electric field; B- induction of a magnetic field; m and q- accordingly, the mass and charge of the particle.

Since ra-di-us tra-ek-to-ri depends on the mass and charge of the ion, different ions fall on the screen on different races -sto-i-nii from the source, which also poses-in-la-et them de-de-lyat and ana-li-zi-ro-vat with-becoming a sample.

At the present time, there are many types of mass-spectrum-meters, the principles of work-bo-you-to- then-ryh from-whether-cha-yut-sya from the races-look-ren-no-go above. From-go-tav-li-va-yut-sya, for example, di-na-mi-che-mass-spectrometers, in some masses are studied du-e-my ions are determined by the time of flight from the source to the re-gi-stri-ru-u-th device.

If you press the pedal of the piano and shout at it strongly, then you can hear a reverberation from it, which will be heard for some time, with a tone (frequency) very similar to the original sound.

Analysis and synthesis of sound.

With the help of sets of acoustic resonators, it is possible to establish which tones are included in a given sound and with what amplitudes they are present in a given sound. This establishment of the harmonic spectrum of a complex sound is called its harmonic analysis. Previously, such an analysis was actually carried out using sets of resonators, in particular Helmholtz resonators, which are hollow balls of various sizes, equipped with a process inserted into the ear and having a hole on the opposite side.

It is essential for sound analysis that whenever the analyzed sound contains a tone with the frequency of the resonator, the resonator begins to sound loud in this tone.

Such methods of analysis are very inaccurate and painstaking. At present, they have been superseded by much more advanced, accurate, and fast electroacoustic methods. Their essence boils down to the fact that the acoustic vibration is first converted into an electrical vibration while maintaining the same shape, and therefore having the same spectrum; then the electrical oscillation is analyzed by electrical methods.

One significant result of harmonic analysis concerning the sounds of our speech can be pointed out. By timbre, we can recognize the voice of a person. But how do sound vibrations differ when the same person sings different vowels on the same note: a, i, o, u, e? In other words, how do the periodic fluctuations of air caused by the vocal apparatus differ in these cases with different positions of the lips and tongue and changes in the shape of the mouth and throat cavities? Obviously, in the spectra of vowels there must be some features characteristic of each vowel sound, in addition to those features that create the timbre of the voice of a given person. The harmonic analysis of vowels confirms this assumption, namely, vowel sounds are characterized by the presence in their spectra of overtone regions with large amplitude, and these regions always lie for each vowel at the same frequencies, regardless of the height of the sung vowel sound. These areas of strong overtones are called formants. Each vowel has two characteristic formants.

Obviously, if we artificially reproduce the spectrum of a particular sound, in particular the spectrum of a vowel, then our ear will receive the impression of this sound, although its natural source would be absent. It is especially easy to carry out such a synthesis of sounds (and the synthesis of vowels) with the help of electroacoustic devices. Electric musical instruments make it very easy to change the sound spectrum, i.e. change its tone. A simple switch makes the sound sound like a flute, a violin, a human voice, or quite peculiar, unlike the sound of any of the usual instruments.

Doppler effect in acoustics.

The frequency of sound vibrations that a stationary observer hears when the sound source approaches or moves away from it is different from the frequency of sound perceived by an observer who moves with this sound source, or both the observer and the sound source stand still. The change in the frequency of sound vibrations (pitch) associated with the relative motion of the source and the observer is called the acoustic Doppler effect. When the source and receiver of sound approach, the pitch rises, and if they move away. then the pitch is lowered. This is due to the fact that when a sound source moves relative to the medium in which sound waves propagate, the speed of such movement is vectorially added to the speed of sound propagation.

For example, if a car with the siren on approaches, and then, having passed by, moves away, then a high-pitched sound is heard first, and then a low one.

sonic booms

Shock waves occur during a shot, explosion, electric discharge, etc. The main feature of a shock wave is a sharp pressure jump at the wave front. At the moment of passage of the shock wave, the maximum pressure at a given point occurs almost instantly over a time of about 10–10 s. In this case, the density and temperature of the medium change abruptly at the same time. Then the pressure slowly drops. The power of the shock wave depends on the strength of the explosion. The speed of propagation of shock waves can be greater than the speed of sound in a given medium. If, for example, a shock wave increases the pressure by one and a half times, then the temperature rises by 35 0С and the speed of propagation of the front of such a wave is approximately equal to 400 m/s. Walls of medium thickness that are encountered in the path of such a shock wave will be destroyed.

Powerful explosions will be accompanied by shock waves that create a pressure 10 times higher than atmospheric pressure in the maximum phase of the wave front. In this case, the density of the medium increases by 4 times, the temperature rises by 500 0C, and the propagation velocity of such a wave is close to 1 km/s. The thickness of the shock wave front is of the order of the free path of molecules (10-7 - 10-8 m), therefore, in theoretical consideration, we can assume that the shock wave front is an explosion surface, when passing through which the gas parameters change abruptly.

Shock waves also occur when a solid body moves faster than the speed of sound. In front of an aircraft that flies at supersonic speeds, a shock wave is formed, which is the main factor determining the resistance to the movement of the aircraft. To weaken this resistance, supersonic aircraft are given a swept shape.

The rapid compression of air in front of an object moving at high speed leads to an increase in temperature, which increases with an increase in the speed of the object. When the speed of the aircraft reaches the speed of sound, the air temperature reaches 60 0C. At a speed of movement twice the speed of sound, the temperature rises by 240 0C, and at a speed close to triple the speed of sound, it becomes 800 0C. Velocities close to 10 km/s lead to melting and transformation of the moving body into a gaseous state. The fall of meteorites at a speed of several tens of kilometers per second leads to the fact that already at an altitude of 150 - 200 kilometers, even in a rarefied atmosphere, meteorite bodies noticeably heat up and glow. Most of them completely disintegrate at altitudes of 100-60 kilometers.

Noises.

The superimposition of a large number of oscillations, randomly mixed with respect to each other and arbitrarily changing the intensity in time, leads to a complex form of oscillations. Such complex vibrations, consisting of a large number of simple sounds of different tonality, are called noises. Examples are the rustling of leaves in the forest, the roar of a waterfall, the noise on a city street. Noises can also include sounds expressed by consonants. Noises can differ in distribution in terms of sound strength, frequency and duration of sounding in time. For a long time there are noises created by the wind, falling water, sea surf. Relatively short-term peals of thunder, the rumble of waves are low-frequency noises. Mechanical noise can be caused by the vibration of solid bodies. The sounds that occur during the bursting of bubbles and cavities in the liquid, which accompany the cavitation processes, lead to cavitation noise.

In practice, it is more often necessary to solve the inverse problem with respect to the problem considered above - the decomposition of a certain signal into its constituent harmonic oscillations. In the course of mathematical analysis, such a problem is traditionally solved by expanding a given function in a Fourier series, i.e., in a series of the form:

where i =1,2,3….

A practical Fourier series expansion, called harmonic analysis , consists in finding the quantities a 1 ,a 2 ,…,a i , b 1 ,b 2 ,…,b i , called the Fourier coefficients. By the value of these coefficients, one can judge the proportion in the investigated function of harmonic oscillations of the corresponding frequency, a multiple of ω . Frequency ω called the fundamental or carrier frequency, and the frequencies 2ω, 3ω,… i ω - respectively the 2nd harmonic, 3rd harmonic, i th harmonic. The application of methods of mathematical analysis makes it possible to expand in a Fourier series most of the functions that describe real physical processes. The use of this powerful mathematical apparatus is possible under the condition of an analytical description of the function under study, which is an independent and often not an easy task.

The task of harmonic analysis can be formulated as a search in a real signal for the fact of the presence of a particular frequency. For example, there are methods for determining the rotational speed of a turbocharger rotor based on the analysis of the sound that accompanies its operation. The characteristic whistle heard when a turbocharged engine is running is caused by air vibrations due to the movement of the compressor impeller blades. The frequency of this sound and the rotational speed of the impeller are proportional. When using analog measuring equipment in these cases, they proceed something like this: simultaneously with the reproduction of the recorded signal, oscillations of a known frequency are created with the help of a generator, sorting through them in the studied range until resonance occurs. The oscillator frequency corresponding to the resonance will be equal to the frequency of the signal under study.

The introduction of digital technology into measurement practice makes it possible to solve such problems using computational methods. Before considering the main ideas underlying these calculations, let us show the distinctive features of the digital representation of the signal.

Discrete methods of harmonic analysis

Rice. 18. Quantization in amplitude and time

a – original signal; b is the result of quantization;

in , G - saved data

When using digital equipment, a real continuous signal (Fig. 18, a) is represented by a set of points, more precisely, by the values of their coordinates. To do this, the original signal coming, for example, from a microphone or an accelerometer, is quantized in time and amplitude (Fig. 18, b). In other words, the measurement and storage of the signal value occurs discretely after a certain time interval Δt , and the value of the quantity at the time of measurement is rounded to the nearest possible value. Time Δt called time discretization , which is inversely related to the sampling rate.

The number of intervals into which the double amplitude of the maximum allowable signal is divided is determined by the capacity of the equipment. It is obvious that for digital electronics, which ultimately operates with Boolean values ("one" or "zero"), all possible bit depth values will be defined as 2 n. When we say that the sound card of our computer is 16-bit, this means that the entire allowable interval of the input voltage value (y-axis in Fig. 11) will be divided into 2 16 = 65536 equal intervals.

As can be seen from the figure, with the digital method of measuring and storing data, some of the original information will be lost. To improve the accuracy of measurements, it is necessary to increase the bit depth and sampling frequency of the converting technique.

Let's return to the task at hand - to determine the presence of a certain frequency in an arbitrary signal. For greater clarity of the techniques used, consider a signal that is the sum of two harmonic oscillations: q=sin 2t +sin 5t , given with discreteness Δt=0.2(Fig. 19). The table in the figure shows the values of the resulting function, which we will further consider as an example of some arbitrary signal.

Rice. 19. Signal under study

To check the presence of the frequency of interest to us in the signal under study, we multiply the original function by the dependence of the change in the oscillatory value at the frequency being checked. Then we add (numerically integrate) the resulting function. We will multiply and sum the signals at a certain interval - the period of the carrier (fundamental) frequency. When choosing the value of the main frequency, it must be borne in mind that it is possible to check only a large, in relation to the main, in n times the frequency. We choose as the main frequency ω =1, which corresponds to the period.

Let's start checking immediately with the "correct" (present in the signal) frequency y n =sin2x. On fig. 20, the actions described above are presented graphically and numerically. It should be noted that the result of the multiplication passes predominantly above the x-axis, and therefore the sum is noticeably greater than zero (15.704>0). A similar result would be obtained by multiplying the original signal by q n =sin5t(the fifth harmonic is also present in the studied signal). Moreover, the result of calculating the sum will be the greater, the greater the amplitude of the signal under test in the test.

Rice. 20. Checking the presence of the component in the signal under study

q n = sin2t

Now let's perform the same actions for a frequency that is not present in the signal under study, for example, for the third harmonic (Fig. 21).

Rice. 21. Checking the presence of the component in the signal under study

q n =sin3t

In this case, the multiplication result curve (Fig. 21) passes both in the region of positive and negative amplitudes. Numerical integration of this function will give a result close to zero ( ∑ =-0.006), which indicates the absence of this frequency in the signal under study, or, in other words, the amplitude of the studied harmonic is close to zero. Theoretically, we should have received zero. The error is caused by the limitations of discrete methods due to the finite size of the bit depth and sampling rate. By repeating the steps described above the required number of times, you can find out the presence and level of a signal of any frequency that is a multiple of the carrier.

Without going into details, we can say that approximately such actions are performed in the case of the so-called discrete Fourier transform .

In the considered example, for greater clarity and simplicity, all signals had the same (zero) initial phase shift. To take into account possible different initial phase angles, the above operations are performed with complex numbers.

There are many algorithms for the discrete Fourier transform. The result of the transformation - the spectrum - is often presented not as a line, but as a continuous one. On fig. 22 shows both variants of the spectra for the signal studied in the considered example

Rice. 22. Spectra Options

Indeed, if we in the example considered above performed a check not only for frequencies strictly multiples of the fundamental, but also in the vicinity of multiple frequencies, we would find that the method shows the presence of these harmonic oscillations with an amplitude greater than zero. The use of a continuous spectrum in the study of signals is also justified by the fact that the choice of the fundamental frequency in studies is largely random.

The harmonic analysis of sound is called

A. establishing the number of tones that make up a complex sound.

B. establishing the frequencies and amplitudes of tones that make up a complex sound.

Correct answer:

1) only A

2) only B

4) neither A nor B

Sound analysis

With the help of sets of acoustic resonators, it is possible to establish which tones are included in a given sound and what their amplitudes are. Such an establishment of the spectrum of a complex sound is called its harmonic analysis.

Previously, sound analysis was performed using resonators, which are hollow balls of various sizes with an open process inserted into the ear and a hole on the opposite side. It is essential for the analysis of sound that whenever the analyzed sound contains a tone whose frequency is equal to the frequency of the resonator, the latter begins to sound loud in this tone.

Such methods of analysis, however, are very inaccurate and laborious. At present, they have been superseded by much more advanced, accurate, and fast electroacoustic methods. Their essence boils down to the fact that the acoustic vibration is first converted into an electrical vibration with the preservation of the same shape, and therefore having the same spectrum, and then this vibration is analyzed by electrical methods.

One of the essential results of harmonic analysis concerns the sounds of our speech. By timbre, we can recognize the voice of a person. But how do sound vibrations differ when the same person sings different vowels on the same note? In other words, what is the difference in these cases between periodic air vibrations caused by the vocal apparatus at different positions of the lips and tongue and changes in the shape of the oral cavity and pharynx? Obviously, in the spectra of vowels there must be some features characteristic of each vowel sound, in addition to those features that create the timbre of the voice of a given person. The harmonic analysis of vowels confirms this assumption, namely: vowel sounds are characterized by the presence in their spectra of overtone regions with large amplitude, and these regions always lie for each vowel at the same frequencies, regardless of the height of the sung vowel sound.

What physical phenomenon underlies the electroacoustic method of sound analysis?

1) conversion of electrical vibrations into sound

2) decomposition of sound vibrations into a spectrum

3) resonance

4) conversion of sound vibrations into electrical

Decision.

The idea of the electroacoustic method of sound analysis is that the studied sound vibrations act on the microphone membrane and cause its periodic movement. The membrane is connected to a load, the resistance of which changes in accordance with the law of movement of the membrane. Since the resistance changes with a constant current strength, the voltage also changes. They say that there is a modulation of the electrical signal - there are electrical oscillations. Thus, the basis of the electroacoustic method of sound analysis is the conversion of sound vibrations into electrical ones.

The correct answer is number 4.