Exploring Various Types of Hearing Instrument Used Over the Ages
Research suggests that the earliest type of hearing instrument for those who were afflicted with partial deafness may have appeared as early as the late 16th century. It was a shell-like device fashioned from metal or wood, designed to fit over the ear and to direct ambient sounds directly into the ear canal. Its design suggests that it could provide only limited amplification and it was soon replaced by the more efficient ear trumpet which gained popularity during the following century.
Both static versions, supported by stands, and smaller, more portable units that had to be held by the user, were developed in large numbers. However, since these ear trumpets were just simple acoustic devices, the level of amplification possible with these types of hearing instrument was in direct proportion to their size and, as one can imagine, for those with more profound forms of deafness, their use proved to be totally impractical in many situations and the speaking tubes introduced later in the century proved to be of more use in many situations. These were simple devices that directed the voice of a speaker at one end to the ear of the listener at the other.
Perhaps the most impressive of all acoustic devices was that designed for use by Portugal’s King John VI in the early 1800s. It consisted of an ornately carved throne designed to collect sound via the open mouths of the lions that formed its arm rests. From there the sound was passed to the king’s ear via a speaking tube concealed elsewhere in its structure.
The next types of hearing instrument to emerge employed electrical power and became feasible with the invention of the telephone and microphone towards the end of the 19th century. Siemens was among the first companies to manufacture these on a commercial scale and although they were still quite bulky and not readily portable, they had a speaker that could be fitted into the ear and were thus a huge improvement on the even bulkier acoustic devices.
Electronic amplification with the use of vacuum tubes or valves was the nest step forward and the earliest device to employ this technology appeared in 1920 and although it weighed just over 3 kilograms it was sufficiently portable prompt Marconi and Western Electric to start production. Despite initial teething troubles with damp, the tiny transistor that replaced the vacuum tube led to types of hearing instrument that were both far smaller and more efficient.
By the early ‘60s the digitisation of sounds became possible but required massive mainframe computers and so it was not until the development of the microprocessor a decade later, that digital devices able to compensate for auditory impairment became a practical solution. Within the next ten years the first real-time miniature, digital heating aid was produced at New York’s City University and utilised an FM radio transmitter to relay incoming sounds via a cable to a receiver worn in the ear. This marked the onset of a digital revolution that made possible, not just crystal clear, wireless sound from near-invisible devices but seamless integration with other digital devices and, ultimately, the cochlear implant or bionic ear that marks the pinnacle of achievement among the evolving types of hearing instrument.