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Techniques & Technologies

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Hearing aids

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Hearing aids make sound louder and direct it into the ear. They are worn near or in the ear.

Before the 20th century hearing aids used simple non-electric technology. Ear trumpets were popular and became more effective during the 1800s. The length and shape of the horn-like devices determined their effectiveness in transmitting sound.

Electric hearing aids were developed at the start of the 20th century. Like telephones, electric hearing aids used a microphone to convert sound into electrical signals. An amplifier made the sound signals louder, then a receiver turned the electrical signals back into sound and transmitted them into the ear. The first electric hearing aids were large and impractical desktop devices, but as technology improved components got smaller. After transistors were introduced hearing aids became more portable. However, sophisticated hearing aids offering better sound reception are expensive.

In the 1950s scientists worked on a bionic ear. Other teams improved the device, and it gained the name ‘cochlear implant’. Unlike hearing aids, cochlear implants do not amplify sound. These surgically implanted devices stimulate hearing nerves inside the ear, providing a sense of sound to a profoundly deaf person. After implantation, rehabilitation therapy teaches people how to understand what they hear. The technology is controversial. Some in the Deaf community argue implants correct something which does not need correcting. Others question the ethics of giving implants to children too young to make their own decisions about the technology.

Bibliography

E Bennion, Antique hearing devices (London: Vernier Press, c1994)

K Berger, ‘From telephone to electric hearing aid’, Volta Review, 78 (1976), pp 83-89

S Blume, ‘Histories of cochlear implantation’, Social science and medicine, 4 (1999), pp 1257-1268

A Mudry and L Dodele, ‘History of the technological development of air conduction hearing aids’, The Journal of Laryngology and Otology, 114 (2000), pp 418-423

M Koelkebeck, D Calvert and C Detjen, Historic devices for hearing: The CID-Goldstein collection (Missouri: Central Institute for the Deaf, 1984)

Glossary:

Bionic

Artficial body parts, usually electronic and mechanical.