The history of implantable technology. Hearing Aids
The first official mention of hearing aids appeared in a book published in 1588 under the name Magia Naturalis. In it, the Italian doctor, scientist and cryptographer Giovanni Battista Porta describes devices made of wood and repeating the shape of the ears of animals, naturally endowed with a sharp ear.
For several centuries, the device has evolved into a tiny device that is almost invisible to the naked eye and does not even remotely resemble the organs of hearing of representatives of the animal kingdom. The speed of technology development can hardly be called rapid - right up to the discovery of electricity, people with limited hearing capabilities had to use all kinds of pipes, the size of which often reached half a meter.
Already in the XIII century, people with hearing loss used the hollowed-out horns of cows and sheep as primitive hearing aids. Their construction did not change until the 18th century, when more modern pipes were invented. Funnel-shaped ear tubes in their structure were the first person's attempt to invent a device for the treatment of hearing loss. Most of these early devices were made from animal horns or shells and were quite large — 40–60 cm in length and about 15 cm in the widest part. They did not amplify the sound, but “collected” it and sent it through a narrow tube into the ear.
In the XVIII century, the effect of bone conduction was also discovered. During this process, sound vibrations are transmitted through the skull to the brain. Small fan-shaped devices were placed behind the ears, collected sound waves and sent them through the bone behind the ear.
Until humanity discovered electricity and telephones in the 19th century, hearing aids remained the only way to help people with hearing loss live a full life.
Later for the manufacture of pipes began to use metals - copper and brass. Masters learned how to arrange auditory tubes in various styles, depending on the preferences of the client and the degree of hearing loss. The most famous fan of auditory tubes is Ludwig van Beethoven. The composer suffered from severe tinnitus- tinnitus prevented him from perceiving and evaluating music, and around 1796 he began to lose his hearing. Beethoven’s house museum in Bonn contains a large collection of hearing aids that helped him to hear music and speech.
The collection of auditory tubes by Ludwig van Beethoven.
In the 19th century, the disguise of hearing aids was emphasized. Although the devices were still quite large, craftsmen managed to turn them into attractive decorative accessories and embed them in collars, hats and hairstyles. Sometimes they were covered with enamel of the skin color or the hair color of the client. Some men tried to completely hide the device in the beard.
Members of some royal families owned vehicles built right into the thrones. Special tubes that collect voices and sounds were passed through the armrests. The sound was sent to the echo chamber and amplified, and then went out of the hole near the head of the monarch.
One of these cleverly disguised hearing aids was made for the King of Portugal, João VI: the armrests of the throne were made in the shape of lions with open mouths. Each of them housed a resonator, which caught the sound and sent it to the headphone.
The throne of João VI
Around the same period, another type of hearing aid was invented: the speaking tube. Its wider end was held to the speaker’s mouth, and the other was placed directly to the listener's ear. Not very convenient, but more efficient.
In the early 1900s, with the advent of electricity and a telephone, new-generation hearing aids began to develop with an electronic sound amplifier, a carbon microphone and a battery. Such devices were bulky boxes that had to be worn around the neck. Out of the box came out long wires that joined a heavy battery that worked for only a few hours. To extend the life of such devices, some people wore even heavier and larger batteries. In addition, the more serious the hearing problems were, the larger the microphone had to be used.
One of the first electric coal hearing aids
Such devices, despite all the technological improvements, did not demonstrate major improvements. Most of them amplified speech only up to 15 dB, which is not very much, when usually the volume of speech is on average 60 dB. And even the enhanced speech did not sound very good: the sound was noisy, creaky, and a person could only distinguish a very narrow range of acoustic signals.
The emergence of a vacuum tube significantly accelerated the progress of hearing aids. They were able to transmit sounds that were much louder and cleaner than coal-powered electrical hearing aids. Some could amplify the sound to 70 dB and higher. However, this improvement affected the size of the device. The early lamp apparatuses were about the same size as the early coal ones. The first tube hearing aid was invented in 1920 and resembled a brick in size.
Like the coal-powered electrical hearing aids, tube lamps became less and less over time. Later projects could be tied around the chest or arm. Vacuum tubes and batteries interfered with further reduction of the apparatus.
The invention of the transistor in the 50s completely changed all types of technology, and especially influenced the technology of hearing aids. They worked about the same as vacuum tubes, but they were much smaller. Transistors began to be used in hearing aids two years before they first appeared in transistor radios.
Transistor hearing aid
The first shipments of transistor hearing aids occurred in 1953. Devices quickly gained popularity: in the year of production, about 50% of sales accounted for exactly the transistor, and in 1954 - 97%.
The earliest transistor devices were about the same size as the late tube. By 1956, they were already small enough to be embedded behind the ear. Such a design decision is still encountered.
Hearing glasses developed by Otarion Electronics became another popular device at that time. By 1959, half of all transistor devices were made in the form of glasses, and even people with excellent eyesight preferred to wear them.
In the 1960s, the first devices were developed, which were placed directly in the auricle. Then they were not as reliable as their larger contemporaries, but over time the technology was refined.
The emergence of silicon transistors allowed us to create hearing aids that are close to what we know today. The first such device was developed by Zenith Radio in the 60s. In these versions, the microphone came out of the ear and a small wire attached to the amplifier, which was attached to the ear. This technology remained virtually unchanged until the 1980s, when digital signal processing chips were used for hearing aids.
All devices of the time, transistor or lamp, worked on the same principle: they caught sound waves, amplified them and sent them to their ears. In other words, they simply provide the ear with a loud sound. All their work relies on a properly functioning inner ear that converts sound waves into neural signals. The devices could not help those whose ear is not functioning properly. Cochlear implantation
came to the rescue of these people . Cochlear implants sent electrical signals directly to the cochlea , part of the ear that senses and recognizes sounds. They were intended for patients with profound hearing loss who cannot use normal hearing aids.
The first experiments in electrical stimulation of the cochlea belong to 1957. For the first time, a medical device was able to replace the human feeling - it helped people to hear, even if they were born deaf. In the 1970s, mass implant development began in laboratories around the world. In 1973, Dr. William House introduced one of the first widely used clinically cochlear implants.
The microprocessor invented by Edward Hoff allowed miniaturization of logic functions in electronic equipment. Hearing aids using microprocessors began to appear in the late 1980s. The earliest wearable Audiotone digital hearing aid appeared in 1983. It had ear pieces that were embedded in A / D, D / A and DSP switches. Digital devices created during this period could effectively reduce environmental noise while improving speech quality. All hearing technologies on the market today are mostly digital.
By 2000, hearing aids could be programmed, which made it possible to add a number of user preferences. By 2005, digital devices took up about 80% of the hearing aid market. Digital technology uses the same circuitry as mobile phones and computers.
Modern hearing aids can be configured by hearingologists depending on the individual characteristics of the patient. They can adapt them to different hearing environments and connect additional devices such as computers, televisions and telephones. Antennas, Bluetooth and FM connections ensure compatibility with other electronic devices and access to them in public places. In 2011, Siemens, a well-known manufacturer of technological devices, launched Aquaris, one of the first waterproof and dustproof, anti-shock hearing aids.
Today, hearing aids continue to evolve with the high-tech world. Smart devices appear on the market, which adapt to different situations automatically, without user intervention. In 2015, ReSound developed the first hearing aid for a smartphone that doesn’t need intermediate sensors. It is designed specifically for the iPhone helps to hear the device better.