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 sense organs is the hearing organ, thanks to which a person communicates and receives most of the information.
A person lives in a permanent world of sounds, thanks to which he receives an indispensable source of information about the world that surrounds him. The roar of the sea surf and the rumble of the wind, the chirping of birds, the conversations of people and the growling of animals, the peals of thunder are sources of sound in nature that help a person adapt to the environment.
How does one hear?
If you look inside the human ear, you can see a membrane called the tympanic membrane. It stretches along the tunnel leading inside the ear. Air vibrations from a sound source hit the eardrum, causing it to vibrate as well. Behind the eardrum is a bony space filled withthree moving bones called the malleus, anvil, and stirrup, so named 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 the cochlea. Vibrations from bones that move create waves in the liquid, like waves in the ocean. Like algae underwater, thousands of hair cells undulate through the liquid. These cells are fundamentally important for hearing. The 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, or the chirping or chirping of birds.
Where does the sound come from?
What is the source of the sound? Any physical body or phenomenon that oscillates with a sound frequency, since waves emanating from it arise in the environment. Humans 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 in a wheat field on a windy day. The air molecules bump into each other and move apart, and the wave passing through the air is just the rhythmic contraction and expansion of the flow of air molecules - a kind of vibration. But other materials also carry sound waves, such as wood, which is a source of sound as well. If you shout from one side closedwooden door, the vocal cords of the screaming person will vibrate first, which in turn will cause the air to vibrate. The air makes the wood of the door vibrate, and then the vibration is transmitted from the door into the air and further, to the person standing on the other side of the door. In a cave, walls do not absorb or transmit sounds the way doors do. They ricochet them back like a mirror of light. Some valleys in Europe are known for their echoes. For example, one sound from a hunting horn can be repeated 100 times until it finally stops.
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 put a large seashell to your ear, you can hear a distant noise, reminiscent of the roar of the surf, not without reason, returning from the sea, many bring home a shell with a living memory of the sea. As attractive as this idea may seem, the noise that is heard has nothing to do with the sea. Instead, the ear hears multiple echoes of all the sounds outside the shell. Natural sources of sound include the rustling of leaves and the singing of birds, 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 is endless.
Sound wave mechanism
Echoes are sound waves that bounce off a smooth surface and reach the ear. For example, if you shout in a cave, you cana fraction of a second later to hear your voice bounce off the walls of the cave and come back. This is how the sea shell works. The best examples of sound sources would be those sinks that have many empty chambers. They are like rooms in an empty house. The walls near the sink are smooth, which means that sounds near the sink, even the quietest, are repeated in the chambers. All echo - from people talking, music or natural sounds - turns into a roar. The beat of the heart can also be added to it, which is picked up and beaten off by the sink. The beautiful effect of many echoes is heard by the sound of the surf.
Sound conversion
No matter how loudly a person shouts, after 100-200 meters no one will hear him, except that he will shout on the phone. The word "telephone" is translated from Greek as "distant sound". During a telephone conversation, sound waves are converted into electrical current. During the reception, the reverse process occurs. Such a current can overcome any distance, propagating in the air like sound waves. A microphone is built into the handset, which reacts to air vibrations that occur during a conversation. The microphone converts these vibrations into alternating current. It propagates along the wires of the telephone line and reaches the subscriber at the other end of the line. But, since a person does not feel alternating current vibrations, it is necessary to turn them into sound vibrations that can be heard. This function is performed by a small loudspeaker built into the handset. Electric waves affect the magnetic field,changing its power. This causes the membrane to vibrate, producing sound waves that are identified as the caller's voice.
What waves does a person hear?
Only waves that can be heard by humans are called sound waves.
Sound is mechanical waves of a certain range that can be distinguished by a person. Studies show that the human hearing organs receive waves in the range 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 within the range of audibility and are not felt by a person.
The picture shows the human hearing range.
Infrasound Sound Ultrasound
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0 16–20 20000 Hz
Other frequencies are distinguishable by individual animals or insects, including fish, butterflies, dogs and cats, bats, dolphins.
How to identify the sound source? Sources are all kinds of bodies that create vibrations with sound frequency (from 16 to 20000 Hz)
Artificial sources
Everything that is created by man, and not by nature, can be attributed to artificial sound sources, examples: tuning fork, bell, tram, radio, computer. You can experiment how a sound wave is created. For the experiment, you need a metal ruler clamped in a vise. If you act on the ruler, you can notice vibrations, but no sound will be heard. But at the same time, a mechanical wave is formed near the ruler. The vibration range of the ruler is below the audio frequency, so the person does not hear the sound. Based on this experience, a device called a tuning fork was invented at the end of the 19th century.
Sound is produced only when a body vibrates at a sound frequency. The waves go in different directions. There must be a medium between the ear and the sound source. It can be a gas, a liquid, a solid surface, but it must certainly be particles that transmit waves. The transmission of sound vibrations is carried out only where there is such an environment. If there is no substance, there will be no sound.
Conditions required to get sound
To create a sound wave must be:
- Source.
- Wednesday.
- Hearing aid.
- Frequency 16-20000 Hz.
- Intensity.
Sound perception is a subjective process, which depends on the state of the auditory organ and the person's well-being. Microphones work on the same principle as ears, only instead of an eardrum, the microphone contains a small, thin metal plate attached to a magnet. As the air pressure on the plate changes, the magnet wobbles and electrical vibrations are produced.
Acoustic Achievements
In the past, people saved sound in various ways: on vinyl records, photographic films, or as magnetic particles on magnetic tape. The computer as a sound source stores information about the current level, regularly reads the levelvoltage and store 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, information media (hard drives, DVD, CD, Blu-ray discs) and output them to the speakers.
The development of digital technology does not stand still. In just 100 years, the progress of sound has progressed from the era of mechanical recording, from music boxes, to the era of digital recording. Advances in acoustics are already amazing.
Scientists have found a way to transfer data from computer to computer using only sound. An acoustic scalpel has been created that can cut even a single cell, nanotechnologists are already developing a way to recharge a mobile phone using voice. In the future, humanity is waiting for incredible discoveries, in which sound will take a direct part.
