History of hearing aids and hearing aid batteries
From the first ear trumpet to electronic hearing aids with small hearing aid batteries.
The first hearing aid was invented as early as the 18th century. But it was a long time before batteries were used in hearing aids. In those days, people simply used a funnel, or so-called ear drum. It was a long time before hearing aids with accessories, wax filters and cleaning set became part of hearing aid history.
How did the development of the hearing aid begin?
At the end of the 19th century, the use of ear trumpets became increasingly common. Collapsible conical ear trumpets were made to order by instrument makers. Well-known models of the period were the Townsend Trumpet, made by the hearing pedagogue John Townshend. The first company to begin commercial production of the ear trumpet was founded by Frederick C. Rein in London in 1800. Rein also produced speaking tubes. These helped to amplify sound, while being smaller than the ear trumpet, which was bulkier. Later, however, came smaller and sleeker ear trumpets. Rein was also commissioned to design a special acoustic chair for the King of Portugal, John VI in 1819. It consisted of a throne designed with carved arms that looked like they were opening lion's mouths. These holes captured the sound, which was transmitted to the back of the throne via a tube, and on into the King's ear! This must be one of the most stylish hearing aids of all time.
At the end of the 19th century came the acoustic horn, consisting of a tube that had two ends, a cone to catch the sound, and a smaller one to fit in the ear. Towards the end of the 19th century, concealed hearing aids became increasingly popular. Rein produced many models such as his acoustic headband, where the hearing aid was cunningly hidden in the hair or headdress. It was produced in a variety of shapes. Today these trinkets are popular collectors' items. Hearing aids were also hidden in sofas, clothes and accessories. The trend was towards increasing invisibility to hide the user's disability from others.
The first electric hearing aids were designed after the invention of the telephone and the microphone in the 1870s and 1880s. The technology of the telephone allowed an acoustic signal to be altered. Telephones could control the loudness, frequency and distortion of sound. These abilities were used in the creation of hearing aids.
The first electric hearing aid, called the Akouphone, was built by Miller Reese Hutchison in 1898. He used a carbon transmitter, so that the hearing aid could be portable. The carbon transmitter was used to amplify sound by using a weak signal and turning it into a strong signal using electric current. One of the first manufacturers of electronically amplified hearing aids was Siemens back in 1913. Their hearing aids were bulky and not exactly portable. They were about the size of a thick book, and had a speaker that would be attached to the ear.
Turning speech into electrical signals - the hearing aid emerges
The first vacuum tube hearing aid was patented by Earl Hanson in 1920. Called the Vactuphone, it used telephone transmitters to convert speech into electrical signals. After the signal was converted, it was amplified as it moved to the receiver. The hearing aid weighed 3.5 kilograms, making it somewhat portable. Marconi in England and Western Electric in the US began marketing these types of hearing aids in 1923. No place yet in the market for us selling hearing aid batteries.
During the 1920s and 1930s, vacuum tube hearing aids became more successful and began to decrease in size with better technology. The first portable hearing aid using straw technology went on sale in England in 1936 and a year later in America. In the 1930s, hearing aids began to become popular with the general public. Multi in London patented the first hearing aid to use automatic gain control. The same company introduced a portable version in 1948. Military technological advances that occurred during the Second World War helped the development of hearing aids.
The development of transistors in 1948 by Bell Laboratories led to major improvements in the hearing aid. The transistor was invented by John Bardeen, Walter Brattain and William Shockley. Transistors were created to replace vacuum tubes. They were small, required smaller hearing aid batteries and had less distortion and heat than their predecessors.
Raytheon manufactured transistors and was one of the first companies to mass-produce transistors across America. Raytheon realised that their hearing aid only lasted a short time and started selling the vacuum tube again along with the transistor in hearing aids to get longer operating time.
The technology of putting transistors in hearing aids with hearing aid batteries developed so quickly that it wasn't really tested enough. What was later found was that transistors could not withstand moisture. Because of the moisture, the hearing aid could break down after a few weeks. To prevent this, the transistor was coated to protect it from moisture.
Zenith was the first company to realise the problem with transistors was body heat. Having come to this conclusion, they were the first to supply a new type of transistor in 1952, called the Microtone Transimatic and the Maico Transist in 1954.
Starting in the early 1960s, Bell Telephone Laboratories created a technique for creating both speech and audio signals on a computer. Because of the size of digital computers, the process of bringing this technology to hearing aids was extremely slow. The progression of the audio speech signal also took longer than the length of the electrical signal itself. A computer was required to get the power needed to process sound. This made it almost impossible to imagine the idea that hearing aids could be made into something that could fit on one ear.
The 1970s saw the creation of the microprocessor, which helped to enable the miniaturisation of the hearing aid. In addition, researcher Edgar Villchur developed so-called multi-channel amplitude compression. This technology could adjust the sound so that sounds that were more intense were weakened and sounds that were faint became stronger. The multi-channel amplitude compression system would later be used as the basic design for the first hearing aids to use digital technology. Now hearing aid batteries are also becoming a commercial product.
The six-channel hearing aid is designed and hearing aids are commercialized
Another pioneer in hearing aids was Daniel Graupe, who developed the six-channel hearing aid. The six-channel hearing aid had digital control of the frequency in all channels in 1975. The electro-acoustic characteristics of the hearing aids could be changed at the touch of a button. The user could easily adjust the sound depending on the surrounding environment.The creation of high-speed digital-array processors used in minicomputers opened the door to advances in digital hearing aids. These minicomputers could process audio signals at speeds equivalent to real time. In 1982, City University of New York created the first real-time fully digital hearing aid. The equipment included a digital array processor and a minicomputer. These consisted of an FM radio transmitter and radio receiver. The equipment had a connection between the individual through a transmitter on the body connected by a cable to the ear microphone and the receiver.
The first commercial digital hearing aid was created in 1987 by Nicolet Corporation. The hearing aid contained a body-worn processor that had a wire connection with an ear attached and a transducer. But Nicolet Corporation's hearing aid was not successful and the company had to close down. Two years later, in 1989, the behind-the-ear (BTE) digital hearing aid was launched. Now, all hearing aids had long needed a hearing aid battery.
Bell Laboratories developed a hybrid digital-analog hearing aid. The product was sold to ReSound Corporation. When the hearing aid was introduced to the market, it was hugely successful. This development has contributed to major changes for the hearing aid.
After the success of Resound Corporation, other companies began producing hybrid hearing aids that included analog amplifiers, which were controlled digitally. There were many advantages to these hearing aids, such as storing parameter settings, settings for different acoustic environments, and more advanced methods of signaling, that included multi-channel compression.
The next milestone was to create an all-digital hearing aid. Oticon developed the first digital hearing aid in 1995, but it was only to audiological research centres for research on digital technology in the realm of acoustic amplification. Senso was the first commercially successful model of an all-digital hearing aid, and was created by Widex in 1996. Following the success of Senso, Oticon began marketing its own hearing aid, DigiFocus. Today's digital hearing aids are programmable, allowing the user to control the sound on their own, without the use of a separate controller. The hearing aid can now adapt depending on the environment it is in and often doesn't even need a physical volume button.
Recently, Apple developed a "Made for iPhone hearing aid" (MFI) application that allows users of MFI digital hearing aids to stream phone calls, music and podcasts directly from iOS devices to the hearing aid.
The development of hearing aid battery sales has also changed drastically in the last 5-10 years with the advent of e-commerce in our society.Previously, hearing aid batteries were sold over the counter in pharmacies, but now about half of all hearing aid batteries in the Nordic countries are sold over the internet, and of course at a much lower price than before.