How to make a presentation on sound waves. Physics presentation "sound waves"

Sound waves. Speed ​​of sound

Sound is mechanical waves perceived by the human hearing organs that cause sound sensations.

Sound sources can be any body that vibrates at a sound frequency (from 16 to 20,000 Hz).

Range of audible sounds.

Children

16-22000

Man aged 20

Man aged 35

16-20000

Man aged 50

16-15000

16-12000

Cricket

Grasshopper

10-100000

Frog

50-30000

Dolphin

400-200000

Humans do not perceive infrasound, although they can feel its impact due to resonance.

The frequency of infrasound oscillations is less than 16 per second, i.e. below the threshold of audibility.

The concept of ultrasound

Ultrasound- high-frequency mechanical vibrations of particles of a solid, liquid or gaseous medium, inaudible to the human ear. The frequency of ultrasonic vibrations is above 20,000 per second, i.e. above the threshold of audibility.

Ultrasound and infrasound

Ultrasound and infrasound are as widespread in nature as sound waves. They are emitted and used for their “negotiations” by dolphins, bats and some other creatures.

Sound sources

Natural

Artificial

(tuning fork, string, bell, membrane, etc.)

For sound to exist, it is necessary :

1. Sound source

2. Wednesday

3. Hearing aid

4. Frequency 16–20000 Hz

5. Intensity

Sound wave receivers:

Natural – ear. Its sensitivity depends on the frequency of the sound wave: the lower the frequency of the wave, the less sensitive the ear. Exceptional selectivity: the conductor captures the sounds of individual instruments.

Artificial – microphone. It converts mechanical sound vibrations into electrical ones.

Sound propagation

Sound propagates in any elastic medium - solid, liquid and gaseous, but cannot propagate in space where there is no substance (for example, in a vacuum)

From the history of the discovery of the speed of sound .

The speed of sound in air was first determined in 1708 by the English scientist William Durham. At two points, the distance between which was known, cannons were fired. At both points, the time intervals between the appearance of fire from a shot and the moment when the sound of a shot was heard were measured. Speed ​​of sound in air 340 m/s

Pitch, timbre and volume of sound

part 2

Physical characteristics of sound

Objective:

Sound pressure (pressure exerted by a sound wave on an obstacle in front of it);

Sound spectrum - decomposition of a complex sound wave into its component frequencies;

Sound wave intensity.

Subjective:

- Volume

- Height

- Timbre

Pitch – a characteristic that is determined by the frequency of oscillations . The higher the frequency of the body that produces vibrations, the higher the sound will be.

Timbre called sound color .

Timbre is the difference between two identical sounds performed by different musical instruments.

Volume sound depends on the amplitude of vibrations .

Sound volume

The loudness of the sound depends on the amplitude of the vibrations: the greater the amplitude of the vibrations, the louder the sound.

Loudness is a subjective quality of auditory sensation that allows sounds to be ranked on a scale from soft to loud.

The unit of sound loudness is called sleep.

Timbre.

The quality of musical sound, its peculiar “coloring” is characterized by timbre. Here are some characteristics of timbre: thick, deep, masculine, harsh, velvety, matte, shiny, light, heavy, rich.

The timbre depends on the material from which the instrument is made and on the shape of the instrument.

Pure tone

A pure tone is the sound of a source that vibrates harmonics at the same frequency.

The branches of the tuning fork perform harmonic (sinusoidal) oscillations. Such oscillations have only one strictly defined frequency. Harmonic vibrations are the simplest type of vibration. The sound of a tuning fork is in a clear tone .

Noise - These are loud sounds of different frequencies, merged into a discordant sound.

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Slide captions:

Sound sources. Sound characteristics.

Sound is mechanical waves perceived by the human hearing organs that cause sound sensations. Sound sources can be any body that vibrates at a sound frequency (from 16 to 20,000 Hz).

A sound wave is a longitudinal wave, so it can propagate in solid, liquid and gaseous media.

Children A person aged 20 years A person aged 35 years A person aged 50 years Hz 16-22000 16-20000 16-15000 16-12000 Cricket Grasshopper Frog Dolphin Hz 2-4000 10-100000 50-30000 400-200000 Range of audible sounds.

Humans do not perceive infrasound, although they can feel its impact due to resonance. The frequency of infrasound oscillations is less than 16 per second, i.e. below the threshold of audibility.

The concept of ultrasound Ultrasound is high-frequency mechanical vibrations of particles of a solid, liquid or gaseous medium, inaudible to the human ear. The frequency of ultrasonic vibrations is above 20,000 per second, i.e. above the threshold of audibility.

Ultrasound and infrasound Ultrasound and infrasound are as widespread in nature as waves in the sound range. They are emitted and used for their “negotiations” by dolphins, bats and some other creatures.

Sound sources Natural (murmur of a stream, bird voices, light splash of water) Artificial (tuning fork, string, bell, membrane, etc.)

For the existence of sound you need: 1. Source of sound 2. Environment 3. Hearing aid 4. Frequency 16–20000 Hz 5. Intensity

: Sound wave receivers: Natural - ear. Its sensitivity depends on the frequency of the sound wave: the lower the frequency of the wave, the less sensitive the ear. Exceptional selectivity: the conductor captures the sounds of individual instruments. Artificial - microphone. It converts mechanical sound vibrations into electrical ones.

Propagation of sound Sound propagates in any elastic medium - solid, liquid and gaseous, but cannot propagate in space where there is no substance (for example, in a vacuum).

From the history of the discovery of the speed of sound. The speed of sound in air was first determined in 1708 by the English scientist William Durham. At two points, the distance between which was known, cannons were fired. At both points, the time intervals between the appearance of fire from a shot and the moment when the sound of a shot was heard were measured. Speed ​​of sound in air 340 m/s

Physical characteristics of sound Objective: - sound pressure (pressure exerted by a sound wave on an obstacle standing in front of it); - sound spectrum - decomposition of a complex sound wave into its component frequencies; - intensity of the sound wave.

Subjective: - Volume - Pitch - Timbre

The pitch of sound is a characteristic that is determined by the frequency of vibrations. The higher the frequency of the body that produces vibrations, the higher the sound will be. Timbre is the color of sound. Timbre is the difference between two identical sounds performed by different musical instruments. The volume of the sound depends on the amplitude of the vibrations.

Volume of sound The volume of sound depends on the amplitude of the vibrations: the greater the amplitude of the vibrations, the louder the sound. Loudness is a subjective quality of auditory sensation that allows sounds to be ranked on a scale from soft to loud. The unit of sound loudness is called sleep.

Timbre. The quality of musical sound, its peculiar “coloring” is characterized by timbre. Here are some characteristics of timbre: thick, deep, masculine, harsh, velvety, matte, shiny, light, heavy, rich. The timbre depends on the material from which the instrument is made and on the shape of the instrument.

Sound vibrations occurring according to the harmonic law are perceived by humans as a musical sound, or tone.

Pure tone The branches of a tuning fork perform harmonic (sinusoidal) oscillations. Such oscillations have only one strictly defined frequency. Harmonic vibrations are the simplest type of vibration. The sound of a tuning fork is a pure tone. A pure tone is the sound of a source that vibrates harmonics at the same frequency.

Noise is loud sounds of different frequencies merged into a discordant sound.

Read more physics and happiness will smile on you!

Slide 2

Speed ​​of sound

Sound travels very quickly, but not indefinitely. The speed of sound can be measured. The time interval between a flash of lightning and a clap of thunder can sometimes reach several tens of seconds. Knowing the distance from the sound source and measuring the delay of the sound, you can determine the speed of its propagation. In dry air at a temperature of 10 °C, this speed turned out to be 337.5 m/s.

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Sound travels very quickly, but not indefinitely. A sound wave has a certain speed. The speed of sound can be measured and calculated...

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...by the lag of thunder from a flash of lightning

Knowing the distance from the sound source and measuring the delay of the sound, you can determine the speed of its propagation. In dry air at a temperature of 10 °C, this speed turned out to be 337.5 m/s.

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Measuring the speed of sound in water

In 1826, Colladon and Sturm carried out the following experiment on Lake Geneva. On one boat, a flash of gunpowder was made and at the same time a hammer struck a bell lowered into the water. On another boat, located 14 km from the first, the time between the flash and the appearance of sound in the horn, also lowered into the water, was measured. The speed of sound in water at 8°C turned out to be 1435 m/s.

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This is interesting In warm air, sound travels faster than in cold air Through a steel pipe, sound travels 20 times faster than in air Sound waves cross a football field in a quarter of a second Sound travels faster in damp air

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Reconnaissance planes can fly faster than sound. They exceed the speed of sound they produce, and the sound waves from them are collected into a shock wave. The clap that you hear on the ground indicates that the sound barrier has been broken. Faster than sound

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Sound waves are not endless. They gradually fade, that is, they lose energy. But sound can be reflected from hard and smooth surfaces. The reflected sound is called an echo. Echo

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Description of the presentation by individual slides:

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Sound waves Completed by: Ruban Anastasia Gabova Valeria, a student of grade 11A, checked by: Glushkova T.A. physics teacher

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Sound Like any wave, sound is characterized by amplitude and frequency spectrum. An ordinary person is able to hear sound vibrations in the frequency range from 16-20 Hz to 15-20 kHz. Sound below the range of human audibility is called infrasound; higher: up to 1 GHz, - ultrasound, from 1 GHz - hypersound. The loudness of a sound depends in a complex way on the effective sound pressure, frequency and shape of vibrations, and the pitch of a sound depends not only on the frequency, but also on the magnitude of the sound pressure. Sound is a physical phenomenon that is the propagation of mechanical vibrations in the form of elastic waves in a solid, liquid or gaseous medium. In a narrow sense, sound refers to these vibrations, considered in connection with how they are perceived by the senses of animals and humans.

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Sound waves in gases and liquids can only be longitudinal, since these media are elastic only with respect to compression (tension) deformations. In solids, sound waves can be both longitudinal and transverse, since solids have elasticity with respect to compression (tension) and shear deformations. Sound in gases Sound in liquids

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Sound intensity Sound intensity (or sound intensity) is a quantity determined by the time-average energy transferred by a sound wave per unit time through a unit area perpendicular to the direction of propagation of the wave: The sensitivity of the human ear is different for different frequencies. In order to cause a sound sensation, the wave must have a certain minimum intensity, but if this intensity exceeds a certain limit, then the sound is not heard and causes only a painful sensation. Thus, for each vibration frequency there is a minimum (hearing threshold) and a maximum (pain threshold) sound intensity that can cause sound perception. I=W/(St)

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Sound intensity level Many thousands of teenagers pay for their passion for loud music, especially fashionable nowadays, with acquired hearing loss. Sound Hearing threshold vdb Barely audible sound 0 Whisper near the ear 25-30 Speech of medium volume 60-70 Very loud speech (screaming) 90 Roar of an airliner taking off 120 At rock and pop music concerts in the center of the hall 106-108 At rock and pop music concerts in the center of the hall scenes 120

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The impact of sound waves The Swiss scientist Hans Jenni studied the effect of sound on inorganic matter, including water. Under the influence of sound, a drop of water, vibrating, took the shape of a three-dimensional star or a double tetrahedron in circles. The higher the vibration frequency, the more complex the forms. But as soon as the sound died down, the most beautiful formations again became shaped like a drop of water.

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Japanese scientist Professor Emoto Masaru conducted experiments on the effects of various music, prayers, obscene expressions, positive and negative statements on water. Emoto Masaru's experiments showed that the result of the influence of spiritual and classical music, prayers and words carrying positive energy is the formation of snowflakes of amazing beauty in ordinary water.

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On the contrary, when exposed to obscene expressions and words carrying negative energy, a crystalline structure in ordinary water was not formed at all, and the previously well-formed crystalline structure of the water was destroyed. The structure of water copies the energy-informational field in which it is located, and we are 90% water. The positive or negative energy of the sounds of speech or a piece of music affects the entire body, right down to the cell structure.

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Russian scientists under the leadership of P.P. Garyaeva and the staff of the Institute of General Genetics proved that DNA perceives human speech. If a person uses obscene expressions in his speech, his chromosomes begin to change their structure, a kind of negative program begins to be developed in the DNA molecules, which can be called a “self-destruction program,” and this is passed on to the person’s descendants. Scientists have recorded: a swear word causes a mutagenic effect similar to radiation with a power of a thousand roentgens!

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On the contrary, high-frequency sounds in a range favorable to humans have a beneficial effect on us, increasing energy levels, causing joy and good mood. High-frequency sounds activate brain activity, improve memory, stimulate thinking processes, while at the same time relieving muscle tension and balancing your body in a different way. After studying music written by various composers, French otolaryngologist Alfred Tomatis found that Mozart's music contains the most high-frequency sounds that recharge and activate the brain. It is very useful to listen to the voices of birds and the sounds of nature. An extended speech range (from 60 to 6000 Hz) is also important because speech represents complex signals that, in addition to the fundamental tones, also contain many harmonics that are multiples of them in frequency. Our native Russian language is very promising in this sense, because it includes both very low and very high frequencies. The area of ​​American and English is much narrower.

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Application of sound waves Ultrasonic waves have found more applications in many areas of human activity: in industry, in medicine, in everyday life, ultrasound was used for drilling oil wells, etc. Until now, high-frequency sound waves have been used in medicine only to diagnose the condition of internal organs. Now they are becoming a precision surgeon's instrument. With their help, you can “weld” and destroy tumors without anesthesia, without a single cut of living tissue.

Description of the presentation by individual slides:

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Topic: Sound waves. Objectives: 1. Introduce the concept of sound waves. Consider the features of their occurrence and propagation, the characteristics of sound, the effect of noise on the human body, the interaction of sound waves with matter. 2. Develop memory, logical thinking, and the ability to apply knowledge in non-standard situations. 3. Show the importance of physical knowledge in human life. Maintain a sustained interest in the subject.

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The world of sounds is so diverse, rich, beautiful, diverse, but we are all tormented by the question: Where do sounds come from, that our ears delight us everywhere? It's time to think seriously.

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Man lives in a world of sounds. Sound for humans is a source of information. He warns people about danger. Sound in the form of music, birdsong gives us pleasure. We enjoy listening to a person with a pleasant voice. The sound of rain, the rustle of leaves... - all this is dear to man. Sound waves are commonly called waves perceived by the human ear. The audio frequency range is approximately 20 Hz to 20 kHz. Waves with a frequency of less than 20 Hz are called infrasound, and with a frequency of more than 20 kHz - ultrasound.

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Cause of the sound? - vibration (oscillations) of bodies, although these vibrations are often invisible to our eyes. Sound sources are physical bodies that vibrate, i.e. tremble or vibrate at a frequency of 16 to 20,000 times per second. The vibrating body can be solid, such as a string or the earth's crust, gaseous, such as a stream of air in a wind musical instrument or a whistle, or liquid, such as waves on water. Sound is mechanical elastic waves propagating in gases, liquids, and solids.

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To hear sound you need: 1. a sound source; 2. elastic medium between it and the ear; 3. a certain range of vibration frequencies of the sound source - between 16 Hz and 20 kHz, sufficient for the ear to perceive the power of sound waves.

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SOUND CHARACTERISTICS Volume. Loudness depends on the amplitude of vibrations in the sound wave. The unit of sound volume is 1 Bel (in honor of Alexander Graham Bell, inventor of the telephone). The sound volume is 1B. In practice, loudness is measured in decibels (dB). 1 dB = 0.1B. Sound louder than 180 dB can even cause eardrum rupture.

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Pitch. - determined by the vibration frequency of the sound source. The sounds of the human voice are divided into several ranges in height: bass – 80–350 Hz, baritone – 110–149 Hz, tenor – 130–520 Hz, treble – 260–1000 Hz, soprano – 260–1050 Hz, coloratura soprano – up to 1400 Hz Frequency spectrum of sounds of musical instruments.

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SOUND PROPAGATION. SPEED OF SOUND. The propagation of sound does not occur instantly, but at a finite speed. For sound to propagate, a medium is required - air, water, metal, etc. Sound cannot travel in a vacuum, because... there is no elastic medium here, and therefore elastic mechanical vibrations cannot occur. In each medium, sound travels at different speeds. The speed of sound in air is approximately 340 m/s. The speed of sound in water is 1500 m/s. The speed of sound in metals, in steel - 5000 m/s.

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A TUNING FORK is a U-shaped metal plate whose ends can vibrate when struck. The strongest vibrations will be observed at the ends of the fork. The ends of the fork oscillate, moving away from each other and approaching each other. At the same time, the lower end - the leg of the tuning fork - also vibrates. The sound produced by a tuning fork is very weak and can only be heard at a short distance. A resonator is a wooden box on which a tuning fork can be attached, used to amplify sound. In this case, sound emission occurs not only from the tuning fork, but also from the surface of the resonator. However, the duration of the sound of a tuning fork on a resonator will be shorter than without it.

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E X O A loud sound, reflected from obstacles, returns to the source of the sound after a few moments, and we hear an echo. By multiplying the speed of sound by the time elapsed from its origin to its return, you can determine twice the distance from the sound source to the obstacle. This method of determining the distance to objects is used in echolocation.

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