Simple and complex sound vibrations. Sound analysis What the harmonic analysis of vowels showed

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 indeed 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 (Fig. 43). The action of such a resonator, as well as the action of the resonant box of a tuning fork, we will explain below (§51). For the analysis of sound, it is essential that whenever the analyzed sound contains a tone with the frequency of the resonator, the latter begins to sound loud in this tone.

Rice. 43. Helmholtz resonator

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 At present, they have been superseded by much more advanced, accurate, and fast electroacoustic methods.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 while maintaining the same shape, and therefore having the same spectrum (§ 17); then this electrical oscillation is analyzed by electrical methods.

Let us point out one essential result of harmonic analysis concerning 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: a, i, o, u, e? In other words, what is the difference in these cases between periodic air vibrations caused by the vocal apparatus 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. On fig. 44 shows the position of the formants of the vowels y, o, a, e, and.

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, even if its “natural source” is 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 spectrum of sound, that is, change its timbre.

Discussing the question of the nature of sound waves, we had in mind such sound vibrations that obey the sinusoidal law. These are simple sound vibrations. They are called pure sounds, or tones. But in natural conditions, such sounds are practically not found. The noise of leaves, the murmur of a stream, the peals of thunder, the voices of birds and animals are complex sounds. However, any complex sound can be represented as a set of tones of different frequency and amplitude. This is achieved by conducting a spectral analysis of the sound. A graphic representation of the result of analyzing a complex sound by its constituent components is called the amplitude-frequency spectrum. On the spectrum, the amplitude is expressed in two different units: logarithmic (in decibels) and linear (in percent). If a percentage expression is used, then the reading is most often carried out relative to the amplitude of the most pronounced component of the spectrum. In this case, it is taken as zero decibels, and the decrease in the amplitude of the remaining spectral components is measured in negative units. Sometimes, in particular, when averaging several spectra, it is more convenient to take the amplitude of the entire analyzed sound as the basis for the reading. The quality of sound, or its timbre, essentially depends on the number of sinusoidal components that make it up, as well as on the degree of expression of each of them, that is, on the amplitudes of the tones that compose it. This is easy to verify by listening to the same note played on different musical instruments. In all cases, the fundamental frequency of the sound of this note - for stringed instruments, for example, corresponding to the frequency of the vibration of the string - is the same. Note, however, that each instrument has its own shape of the amplitude-frequency spectrum.

Fig. 1. Amplitude-frequency spectra of the note "do" of the first octave, reproduced on different musical instruments. The amplitude of oscillations of the first harmonic, called the frequency of the fundamental tone, is taken as 100 percent (it is marked with an arrow). The peculiarity of the sound of the clarinet in comparison with the sound of the piano is manifested in a different ratio of the amplitudes of the spectral components, that is, harmonics; in addition, the clarinet sound spectrum lacks the second and fourth harmonics.

Everything said above about the sounds of musical instruments is also true for vocal sounds. The main part of the vocal sounds - in this case it is usually called the fundamental frequency - corresponds to the frequency of the vibration of the vocal cords. The sound coming from the vocal apparatus, in addition to the main tone, also includes numerous accompanying tones. The fundamental tone and these additional tones make up a complex sound. If the frequency of the accompanying tones exceeds the frequency of the main tone by an integer number of times, then such a sound is called harmonic. The accompanying tones themselves and their corresponding spectral components in the amplitude-frequency spectrum of sound are called harmonics. The distances on the frequency scale between adjacent harmonics correspond to the frequency of the fundamental tone, that is, the frequency of vibration of the vocal cords.

Fig. 2. Amplitude-frequency spectra of the sound produced by the vocal cords of a person when he pronounces any vowel (left figure), and the vowel sound "and" created by the vocal tract (right figure). Vertical segments represent harmonics; the distance between them on the frequency scale corresponds to the frequency of the fundamental tone of the voice. The change (decrease) in the amplitude of the harmonics is expressed in decibels relative to the amplitude of the largest harmonic. The so-called formant frequencies (F 1 , F 2 , F 3 ) appeared on the envelope of the spectrum of the sound "and", which are the largest harmonic components in amplitude.

As an example, consider the process of formation of speech sounds. During the pronunciation of any vowel, the oscillating vocal cords create a complex sound, the spectrum of which consists of a series of harmonics with gradually decreasing amplitude. For all vowels, the spectrum of sound produced by the vocal cords is the same. The difference in the sound of vowels is achieved due to changes in the configuration and size of the air cavities of the vocal tract. So, for example, when we pronounce the sound "and", the soft palate blocks the access of air to the nasal cavity and the front part of the back of the tongue rises to the sky, as a result of which the oral cavity acquires certain resonant properties, modifying the original spectrum of the sound created by the vocal cords. In this spectrum, a number of peaks in the amplitude of the spectral components, specific for a given vowel sound, appear, called spectral maxima. In this case, one speaks of a change in the envelope of the sound spectrum. The energetically most pronounced spectral maxima, due to the operation of the vocal tract as a resonator and filter, are called formants. Formants are designated by serial numbers, and the first formant is considered to be the one that follows immediately after the fundamental tone frequency.

In the form of a sum of harmonic vibrations, one can represent not only voice sounds, but also various noises made by animals: sniffling, snorting, knocking and smacking. Since the spectra of noise sounds consist of many tones closely adjacent to each other, it is impossible to distinguish individual harmonics in them. Typically, noise sounds are characterized by a fairly wide range of frequencies.

In bioacoustics, as in technical sciences, all sounds are called acoustic or sound signals. If the spectrum of an audio signal covers a wide frequency band, the signal itself and its spectrum are called broadband, and if narrow, then narrowband.

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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.

The application of the method of harmonic analysis to the study of acoustic phenomena made it possible to solve many theoretical and practical problems. One of the difficult questions of acoustics is the question of the peculiarities of the perception of human speech.

The physical characteristics of sound vibrations are the frequency, amplitude and initial phase of the vibrations. For the perception of sound by the human ear, only two physical characteristics are important - the frequency and amplitude of vibrations.

But if this is true, then how do we recognize the same vowels a, o, y, etc. in the speech of different people? After all, one person speaks in bass, another in tenor, a third in soprano; therefore, the pitch, i.e., the frequency of sound vibrations, during the pronunciation of the same vowel, turns out to be different for different people. It is possible to sing a whole octave on the same vowel a, changing the frequency of sound vibrations by half, and yet we know that it is a, but not o or y.

Our perception of vowels does not change even when the loudness of the sound changes, that is, when the amplitude of the vibrations changes. And loudly and quietly pronounced, but we confidently distinguish from and, u, oh, e.

An explanation of this remarkable feature of human speech is given by the results of the analysis of the spectrum of sound vibrations that occur when pronouncing vowels.

Analysis of the spectrum of sound vibrations can be carried out in various ways. The simplest of these is to use a set of acoustic resonators called Helmholtz resonators.

An acoustic resonator is a cavity usually spherical

form, communicating with the external environment through a small hole. As Helmholtz showed, the natural frequency of vibrations of air contained in such a cavity, in the first approximation, does not depend on the shape of the cavity and for the case of a round hole is determined by the formula:

where is the natural frequency of the resonator; - speed of sound in air; - hole diameter; V is the volume of the resonator.

If you have a set of Helmholtz resonators with different natural frequencies, then to determine the spectral composition of sound from some source, you need to alternately bring different resonators to your ear and determine by ear the onset of resonance by increasing the volume of the sound. On the basis of such experiments, it can be argued that the composition of complex acoustic oscillations contains harmonic components, which are the natural frequencies of the resonators in which the resonance phenomenon was observed.

This method of determining the spectral composition of sound is too laborious and not very reliable. One could try to improve it: use the entire set of resonators at once, supplying each of them with a microphone for converting sound vibrations into electrical vibrations and with a device for measuring the current strength at the microphone output. To obtain information about the spectrum of harmonic components of complex sound vibrations with the help of such a device, it is enough to take readings from all measuring instruments at the output.

However, this method is not used in practice either, since more convenient and reliable methods for the spectral analysis of sound have been developed. The essence of the most common of them is as follows. With the help of a microphone, the studied sound-frequency air pressure fluctuations are converted into electrical voltage fluctuations at the microphone output. If the quality of the microphone is high enough, then the dependence of the voltage at the microphone output on time is expressed by the same function as the change in sound pressure over time. Then the analysis of the spectrum of sound vibrations can be replaced by the analysis of the spectrum of electrical vibrations. The analysis of the spectrum of electrical oscillations of sound frequency is carried out technically easier, and the measurement results are much more accurate. The principle of operation of the corresponding analyzer is also based on the phenomenon of resonance, but not in mechanical systems, but in electrical circuits.

The application of the spectrum analysis method to the study of human speech made it possible to find that when a person pronounces, for example, the vowel a at a pitch up to the first octave

sound vibrations of a complex frequency spectrum occur. In addition to oscillations with a frequency of 261.6 Hz, corresponding to a tone up to the first octave, a number of harmonics of a higher frequency are found in them. When the tone at which the vowel is pronounced changes, changes occur in the spectrum of sound vibrations. The amplitude of the harmonic with a frequency of 261.6 Hz drops to zero, and a harmonic appears corresponding to the tone at which the vowel is now pronounced, but a number of other harmonics do not change their amplitude. A stable group of harmonics characteristic of a given sound is called its formant.

If you play at 78 rpm a gramophone record with a performance of a song designed to be played at a speed of 33 rpm, then the melody of the song will remain unchanged, but the sounds and words sound not only higher, but become unrecognizable. The reason for this phenomenon is that the frequencies of all the harmonic components of each sound change.

We come to the conclusion that the human brain is able to determine not only the frequency and amplitude of sound vibrations, but also the spectral composition of complex sound vibrations, as if performing the work of an analyzer of the spectrum of harmonic components of non-harmonic vibrations.

A person is able to recognize the voices of familiar people, to distinguish sounds of the same tone obtained using various musical instruments. This ability is also based on the difference in the spectral composition of sounds of the same fundamental tone from different sources. The presence in their spectrum of stable groups - the formant of harmonic components - gives the sound of each musical instrument a characteristic "color", called the timbre of sound.

1. Give examples of non-harmonic vibrations.

2. What is the essence of the harmonic analysis method?

3. What are the practical applications of the harmonic analysis method?

4. How do different vowel sounds differ from each other?

5. How is the harmonic analysis of sound carried out in practice?

6. What is the timbre of sound?

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 vibrations. 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 ...