Man is generously endowed with nature in order to comfortably exist and learn about the world around him. He is able to see bright colors, hear various sounds, catch smells and enjoy the taste of food. One of the most complex sensory organs is the hearing organ, thanks to which a person communicates and receives most of the information.
A person lives in a constant world of sounds, thanks to which he receives an indispensable source of information about the world that surrounds him. The roar of the surf and the roar of the wind, the chirping of birds, the conversations of people and the roar of animals, the thunder are sources of sound in nature that help a person to adapt to environmental conditions.
How does a person hear?
If you look at the human ear from the inside, you can see a membrane called the eardrum. It stretches along the tunnel leading into the ear. Air vibrations emanating from the sound source hit the eardrum, causing it to vibrate as well. Behind the eardrum is a bone space filled with three moving bones, which are called the hammer, anvil and stapes, which were named so because of their shape. These bones pick up vibrations from the eardrum and begin to oscillate.
Deeper in the ear is a fluid-filled canal about 3 cm long, called a snail. The vibrations from the bones that move create waves in the fluid, like waves in the ocean. Like algae under water, thousands of hair cells move in waves in a fluid. These cells are crucial for hearing. Vibrations passing through them push electrical impulses that travel through the auditory nerve to the brain. The brain, in turn, translates these electrical signals into music, voices, the knocking, or chirping of birds.
Where does the sound come from?
What is the source of sound? Any physical body or phenomenon oscillating with sound frequency, since waves emanating from it arise in the environment. People make sounds using their vocal cords. If you put your hands to your throat during a conversation, you can feel the vibration. It is almost always possible to identify sound sources. Sound waves are like waves on a wheat field in windy weather. Air molecules bump into each other and diverge, and the wave passing through the air is simply the rhythmic compression and spread of the flow of air molecules - a form of vibration. But other materials carry sound waves, such as wood, which is the source of sound as well. If you shout from one side of a closed wooden door, first the vocal cords of the screaming person will vibrate, they, in turn, will force the air to vibrate. Air makes the door wood vibrate, and then the vibration from the door is transmitted to the air and on to the person standing on the other side of the door. In a cave, walls do not absorb or transmit sounds like doors do. They throw them back in a ricochet, like light in a mirror. Some valleys in Europe are known for their echoes. For example, one sound from a hunting horn may repeat 100 times until it finally subsides.
Natural sources
The buzzing of a bee or a fly, the squeak of a mosquito, the vocal cords of humans and animals are considered natural sources of sound. If you attach a large seashell to your ear, you can hear a distant noise, reminiscent of the roar of a surf, not without reason, having returned from the sea, many bring home a shell with a living memory of the sea. No matter how attractive this idea may seem, the noise that is heard has nothing to do with the sea. Instead, the ear hears multiple echoes of all sounds outside the sink. The natural sources of sound include the rustling of leaves and birds singing, the murmur of a spring, thunder during a thunderstorm, the chirping of grasshoppers and the creaking of snow underfoot - the enumeration of natural sources of sound waves can be continued indefinitely.
Sound wave mechanism
Echoes are sound waves that repel from a smooth surface and reach the ear. For example, if you shout in a cave, you can hear a voice for a split second later, which has strayed from the walls of the cave and returned back. Thus, the sea shell also acts. The best examples of sound sources are those sinks that have many empty cameras. They resemble rooms in an empty house. The walls at the sink are smooth, which means that sounds near the sink, even the quietest ones, are repeated in the chambers. All echoes - from the conversations of people, music or natural sounds - turn into a rumble. A heartbeat can also be added to it, which is picked up and beat by a sink. The wonderful effect produced by many echoes is heard by the sound of the sea surf.
Sound conversion
No matter how loudly a man screams, after 100-200 meters no one will hear him, unless he will scream on the phone. The word “telephone” is translated from Greek as “distant sound”. During a telephone conversation, sound waves turn into electric current. During reception, the reverse process occurs. Such a current can travel any distance, propagating in the air like sound waves. A microphone is mounted in the handset that responds to air vibrations that occur during a call. A microphone converts these vibrations into alternating current. It spreads over the telephone line and reaches the subscriber at the other end of the line. But, since a person does not feel the fluctuations of the alternating current, it is necessary to turn them into sound vibrations that can be heard. This function is performed by a small loudspeaker mounted in the handset. Electric waves affect the magnetic field, changing its power. This causes the membrane to vibrate, forming sound waves, defined as the voice of the caller.
What waves does a person hear?
Only waves caught by the human ear are called sound waves.
Sound is mechanical waves of a certain range distinguishable by a person. Studies prove that the human hearing organs receive waves ranging from 16 Hz to 20,000 Hz. In addition to them, there are waves whose frequency is below 16 Hz (infrasound) and above 20,000 Hz (ultrasound). But they are not included in the range of hearing and are not felt by a person.
The figure shows the range of audibility of a person.
Infrasound Sound Ultrasound
| ________________ | _______________________________ | ______________________
0 16–20 20,000 Hz
Other frequencies are distinguishable by individual animals or insects, including fish, butterflies, dogs and cats, bats, dolphins.
How to determine the sound source? Sources are all kinds of bodies that create vibrations with sound frequency (from 16 to 20,000 Hz)
Artificial sources
Everything that was created by man, and not by nature, can be attributed to artificial sources of sound, examples: tuning fork, bell, tram, radio, computer. You can experiment how a sound wave is created. For experience, you will need a ruler of metal, clamped in a vice. If you act on the ruler, then you can notice the fluctuations, but you will not hear sound. But a mechanical wave is formed near the ruler. The range of oscillations of the ruler is below the sound frequency, so a person does not hear sound. On such an experiment, at the end of the 19th century, an instrument called a tuning fork was invented.
Sound is formed only when the body vibrates with sound frequency. Waves diverge in different directions. Between the ear and the sound source, there must certainly be a medium. It can be gas, liquid, solid surface, but it must certainly be particles that transmit waves. Sound vibrations are transmitted only where there is such an environment. If there is no substance, there will be no sound.
Requirements for Sound
To create a sound wave should be:
- A source.
- Wednesday.
- Hearing aid.
- The frequency of 16-20000 Hz.
- Intensity.
The perception of sound is a subjective process, which depends on the state of the auditory organ and the well-being of a person. Microphones work on the same principle as ears, but instead of the eardrum, the microphone contains a small, thin metal plate attached to a magnet. As the air pressure on the plate changes, the magnet sways and electrical vibrations are produced.
Acoustic Achievements
In the past, people saved their sound in various ways: on vinyl records, photographic films, or in the form of magnetic particles on magnetic tape. The computer as a sound source stores information about the current level, regularly reads the voltage level and saves each value as a number. Nowadays, almost all computers have a sound card, which allows you to record and play sound messages and music from external devices (microphone, tape recorder, CDs) or process digital audio data recorded on a digital sound source, storage media (hard drives, DVDs) , CD, Blu-ray discs) with their output to the speakers.
The development of digital technology does not stand still. In just 100 years, the progress of sound has advanced from the era of mechanical sound recording, from music boxes to the era of digital sound recording. Advances in acoustics are already staggering.
Scientists have found a way to transfer data from computer to computer using only sound. An acoustic scalpel has been created, capable of separating even one cell, nanotechnologists are already developing a way to recharge a mobile phone using voice. In the future, mankind is waiting for incredible discoveries in which sound will directly participate.