The first sounds 2,5–3 months. Walking: aaa, yy, sh-i, boo-y, hey, etc. 4 months. Pipe: al-le-el-ly, ata-ay, etc. 7-8.5 months. Babble, says syllables: woman, yes, yes, and so on. 8.5-9.5 months. Modulated babble: repeats syllables with various intonations. 9,5–1 year 6 months. Words: Mom,

Memo for parents.

Language is the main means of communication between people. With the help of language, people communicate with each other, convey their thoughts, feelings, and desires. Each language is a complex system. The elements of this system are sounds, words, sentences that are closely related to each other.

Phonetics   - a section of the science of a language in which the sounds of a language, stress, syllable are studied.

Soundit is the basic unit of the language along with the word and the sentence, but unlike the latter, it does not in itself matter. Sounds play an important sense-distinguishing role in the language: they create the external, sound envelope of words and thus help to distinguish words from each other.

Sounds are vowels and consonants.

Vowelsthe sounds we utter only in a voice, you can sing and pull.

Consonant sounds  - Lips, teeth or tongue are involved in their pronunciation.

Consonant sounds are divided into:

Consonants are hard and soft, except for:

C, F, W - always solid

H, U, Y - always soft

The voiced consonant at the end of the word and before the deaf consonant is replaced with the pairing deaf one:

do b [p], trial ka [p].

Consonant sounds before vowels A, O, U, U, E, E sound hard: p ol, m ak, l uk, dy.

At the end of the word and in front of other consonants, too: cat p p ka.

The consonants before the vowel sounds E, E, E, U sound softly: m yach, p, m yod, l yk.

At the end of a word, if we speak softly, a soft sign is written: bear bed. A soft sign is a letter, no sound.

Emphasis- this is the selection of one of the syllables with greater force when pronouncing a word.

The emphasis always falls on the vowel: herbs but , about  zero, p but  to.

The word consists of syllables.

Syllable  - This is one vowel sound or several sounds in a word that are pronounced with one push of air in the process of speaking. How many vowels in a word, so many syllables.

To transmit sounds in the Russian letter, special characters are used - letters.

Do not mix sounds and letter names of these sounds in speech. :

[l] - sound, "el" - letter

[p] - sound, "er" - letter

Speak about the letter - the letter means sound.

Sounds   we hear and say, letters  we see, write and read.

Syntax   - A language science section that studies phrases and sentences.

Phrase  - a combination of two or more independent words related to each other in meaning and grammatically. For example, native country, very interesting.

Offer  called a word or several words that contain a message, a question or urge. The sentence is characterized by intonation and semantic completeness, that is, it represents separate statement.

So, the sentence consists of words. In the sentence, the words are near and they are "friends."

Pretext- “small word”. All words in a sentence and prepositions are written separately. The first word in the sentence is written with a capital letter, a dot, an exclamation point or a question mark is put at the end.

Before proceeding to become familiar with the device of radio receivers, amplifiers and other devices used in broadcasting and radio communications, it is necessary to understand what sound is, how it arises and spreads, how microphones are arranged and work, to get acquainted with the device and the operation of loudspeakers.

Sound vibrations and waves. If you hit a string of a musical instrument (for example, a guitar, a balalaika), then it will begin to oscillate, that is, to make movements in one or the other side from its initial position (rest position). Such mechanical vibrations that cause the sensation of sound are called sound.

The greatest distance that the string deviates in the process of oscillation from its rest position is called the amplitude of oscillations.

The transmission of sound from the oscillating string to our ear is as follows. At a time when the middle part of the string moves to the side where we are, it “crowns” “air particles located near it from this side and thereby creates a“ thickening ”of these particles, i.e. an area of ​​high air pressure appears near the string. This pressure, increased in a certain volume of air, is transmitted to its adjacent layers; as a result, the area of ​​"condensed" air spreads in the surrounding space. At the next point in time, when the middle part of the string moves in the opposite direction, some “vacuum” of air (low pressure area) occurs around it, which spreads after the area of ​​“condensed” air.

The “dilution” of air is again followed by “thickening” (since the middle part of the string will move in our direction again), etc. Thus, with each vibration (forward and backward movement) of the string, an increased pressure area and a lowered region will appear in the air. pressures that move away from the string.

In the same way, sound waves are generated when the loudspeaker is operating.

Sound waves carry the energy received from an oscillating string or cone (paper cone) of a loudspeaker and propagate in air at a speed of about 340 m / s. When sound waves reach the ear, they vibrate its eardrum. At that moment, when the ear reaches the region of "thickening" of the sound wave, the eardrum slightly bends inward. When it reaches the area of ​​"rarefaction" of the sound wave, the eardrum bends slightly outwards. Since the condensation and rarefaction in the sound waves all the time follow each other, then the eardrum either bends inwards and then bends outwards, i.e., it oscillates. These vibrations are transmitted through the complex system of the middle and inner ear through the auditory nerve to the brain, and as a result we feel the sound.

The larger the amplitude of the string oscillations and the ear is closer to it, the louder the sound is perceived.

Dynamic range With very high pressure on the eardrum, i.e., with very loud sounds (for example, with a gunshot), there is pain in the ears. At medium sound frequencies (see below), a painful sensation occurs when sound pressure reaches a value of approximately 1 g / cm2, or 1,000 bar *. Increasing the sensation of loudness with further amplification of sound pressure is no longer felt.

* Bar - a unit used to measure sound pressure values.

Very weak sound pressure on the eardrum does not cause the sensation of sound. The smallest sound pressure, at which our ear begins to hear, is called the threshold of ear sensitivity. At mid frequencies (see below), the threshold of ear sensitivity is approximately 0.0002 bar.

Thus, the area of ​​normal sensation of sound lies between two boundaries: the lower - the threshold of sensitivity and the upper, at which there is pain in the ears. This area is called the dynamic range of hearing.

Note that the increase in sound pressure does not give a proportional increase in sound volume. The sensation of loudness increases much more slowly than sound pressure.

Decibels. Within the dynamic range, the ear can feel an increase or decrease in the volume of a simple monophonic sound (when listening to it in complete silence) if the sound pressure at the mid frequencies increases or decreases by about 12%, i.e., 1.12 times. On this basis, the entire dynamic range of hearing is divided into 120 volume levels, just as the scale of the thermometer between the melting points of ice and boiling water is divided into 100 degrees. Loudness levels on this scale are measured in special units — decibels (abbreviated as db).

In any part of this scale, a 1 db change in volume level corresponds to a sound pressure change of 1.12 times. The zero decibel (“zero” volume level) corresponds to the ear sensitivity threshold, i.e. the sound pressure is 0.0002 bar. At levels above 120 dB, there is pain in the ears.

For example, we point out that in a quiet conversation at a distance of 1 m from the speaker, a volume level of about 40-50 dB is obtained, which corresponds to an effective sound pressure of 0.02-0.06 bar; The highest loudness level of the symphony orchestra is 90–95 dB (sound pressure 7–12 bar).

When using radio receivers, the radio listeners, applying to the size of their rooms, adjust the sound of the loudspeaker so that at the loudest sounds at a distance of 1 m from the loudspeaker, a volume level of 75–85 dB is obtained (respectively, sound pressures of about 1–3.5 bar). In rural areas it is quite enough to have a maximum sound level of the radio transmission not exceeding 80 dB (sound pressure 2 bar).
The decibel scale in radio engineering is also widely used to compare volume levels. To find out how many times one sound pressure is greater than another, when the difference between the corresponding loudness levels in decibels is known, the number 1.12 needs to be multiplied by itself as many times as we have decibels. Thus, a change in the volume level by 2 (56 corresponds to a change in the sound pressure of 1.12. 1.12, i.e., about 1.25 times; a change in the level by 3 dB occurs when the sound pressure changes in 1.12-1 , 12.1.12, i.e. approximately 1.4 times. Similarly, it can be determined that 6 dB correspond to a change in sound pressure about 2 times, 10 dB — approximately<в 3 раза, 20 дб — в 10 раз, 40 дб — в 100 раз и т. д.

Period and frequency of oscillations. Sound vibrations are characterized not only by amplitude, but also by period and frequency. The period of oscillation is the time during which the string (or any other body that creates a sound, such as a loudspeaker diffuser) moves from one extreme position to another and vice versa, that is, makes one complete oscillation.

The frequency of sound vibrations is called the number of vibrations of the sounding body, performed within 1 second. It is measured in hertz (abbreviated as Hz).

If for example, for 1 sec. (440 periods of string oscillations occur (this frequency corresponds to a musical note), then they say that it oscillates at a frequency of 440 Hz. The frequency and period of oscillations are opposite to each other, for example, when the frequency of oscillations is 440 Hz, the oscillation period is 1/440 s .; if the oscillation period is 1/1 000 sec., then the frequency of these oscillations is 1000 Hz.

Band of sound frequencies. The pitch of the sound or tone depends on the oscillation frequency. The higher the oscillation frequency, the higher the sound (tone), and the lower the oscillation frequency, the lower it is. The lowest sound that a person can hear has a frequency of about 20 Hz, and the highest — about 16,000–20,000 Hz. Within these limits or, as they say, in this frequency band are the sound vibrations created by human voices and musical instruments.

Note that speech and music, as well as all sorts of noises, are sound vibrations with a very complex combination of different frequencies (tones of different heights), continuously changing during a conversation or musical performance.

Harmonics. The sound perceived by the ear as the tone of one particular pitch (for example, the sound of a string of a musical instrument, the whistle of a steam locomotive) actually consists of many different tones whose frequencies refer to each other as whole numbers (one to two, one to three and d.) For example, a tone with a frequency of 440 Hz (la note) is simultaneously accompanied by additional tones with frequencies of 440. 2 = 880 Hz, 440 -3 = 1,320 Hz, etc. These additional frequencies are called harmonics (or overtones). A number indicating how many times the frequency of a given harmonic is greater than the fundamental frequency is called the harmonic number. For example, for the main frequency of 440 Hz, the frequency of 880 Hz will be the second harmonic, the frequency of 1,320 Hz will be the third, etc. Harmonics always sound weaker than the fundamental tone.

The presence of harmonics and the ratio of the amplitudes of the various harmonics is determined by the timbre of the sound, i.e. its “coloring”, which distinguishes this sound from another sound with the same fundamental frequency. So, if the third harmonic is strongest, the sound acquires one timbre. If any other harmonic is strongest, the sound will have a different timbre. Changing the strength of the sound of different harmonics leads to a change or distortion of the timbre of the sound.