The first documented evidence of the existence and use of a hearing aid dates back to the 16th century. Its inventor is unknown but many sources from that time discuss several hearing aid devices. In 1588, in his book Magia Naturalis, Giovanni Porta describes hearing aids in the form of animal ears. Later on, other sources talk about horns, trumpets, speaking tubes and various devices worn around the body. However, these were hardly mass manufactured but more likely custom made for specific clients.
In 1800, Frederick C. Rein established in London the first company for commercial manufacture of hearing aids. The hearing aids he offered were non-electric and include acoustic urns, speaking tubes and ear trumpets.
Soon after, in 1836, Alphonsus William Webster patented a curved earpiece worn behind the ear, known as the first British patent for a hearing aid. Even more patents were issued in the upcoming decades. One belonged to James A. Maloney for his ear trumpet with a diaphragm earpiece in 1887. With the beginning of the 20th century hearing aid research and the associated industry developed rapidly. In 1923, vacuum tube hearing aids were introduced and in 1934 they were upgraded to operate with batteries.
In the early 1950s, the vacuum tube hearing aids were replaced with the transistor hearing aids. These led on to the development of the behind the ear and the eyeglass temples models, which in 1954 were already electronic. In 1955, in the ear hearing aid was introduced.
From the 1970s onwards, the hearing aid models began to resemble the modern devices for hearing impairment we know today. The introduction of the electret/FET microphone played an important role in every hearing aid thatmeant that the receiver and the microphone could be kept in one case as forbehind the ear, in the ear and in the canal hearing aids.
The invention of in the canal hearing aid in 1983 was followed by the completely in the canal hearing aid introduced in 1993. Soon after, in 1996, the first successful digital hearing aid device was a fact.
By 2005, 90% of the hearing aid fittings used digital signal processing technology as opposed to the analogue technology.
Nowadays, hearing aids are various and the most common types include behind the ear, in the ear, in the canal, completely in the canal, open fits, receiver in the ear, body worn, bone conduction, CROS, BiCROS and disposable hearing aids.
What is the difference between analogue and digital hearing aid?
Analogue hearing aids, also called conventional, essentially make sound waves louder and amplify all sounds without discriminating between them. Analogue hearing aid devices are made of electronic parts and include a microphone that amplifies the sound and sends it to a receiver (a small loudspeaker) to reproduce it. Some analogue devices can be programmed depending on the environment, such as a quiet place like a museum or a noisy place like a cafe. The different programmes can be changed by pushing a button. Analogue hearing aids are not so common today although they are the cheapest type of hearing aid.
Digital hearing aids use computer chips to convert the sounds into digital signals and thus reproduce them exactly. They are very flexible and can be programmed to fit a particular person’s hearing loss or change in the level of the hearing loss. Many digital hearing aids also adjust automatically the sound level and consider different sound environments. The complex computer processing allows differentiation of sounds such as noise and speech and can reduce background noises.