History of the Hearing Aid

Hearing aids have a colourful history. From the trumpets, to the first electronic hearing aids, aids that were too bulky to be portable, then on to the invention of transistors and next to the digital age. Some of the latest inventions in hearing aids include the use of adaptive dynamic range optimization technology. Hearing aid technology used today is far different from what hearing aids used 100, 50 or even five years ago. Everyday, new technology is available for those with hearing loss.

The earliest hearing aids worked without electricity, while the earliest electric models were simply too large to be portable. Today, digital hearing aids are discrete, lightweight, and have the capability to be adjusted for different environments and to amplify sound without distortion. The future holds many exciting improvements to hearing aid technology as a whole, but it's important to review the history of hearing aids in order to understand just where the industry is headed.

The Early History of Hearing Aids:

Let’s take a look at the history of the hearing aid two hundred years ago, when the hearing aid came in the form of an ear trumpet. The ear trumpet consisted of a large horn-shaped device used to direct sound into the ear of a hearing-impaired person and provide very basic sound amplification without electricity. This form of hearing aid was large and awkward, although some models could be worn on the head attached to a harness. This type of hearing aid performed one basic function; sound amplification. They could also improve the signal-to-noise ratio in a noisy environment but they weren't able to do much else. In fact, cupping your hand behind your ear gives a similar amplification. Hearing aid technology has certainly come a long way since this time.

The Advent of Electric Hearing Aids:

Two important milestones in the history of hearing aids changed the development of the hearing aid.  1. the advent of electricity and 2. Alexander Graham Bell's work on the telephone. The telephone essentially being a machine that could electronically amplify sound via a carbon microphone in combination with a battery. Modern hearing aid technology still utilizes the concept of the tiny speaker inside the hearing aid just as the receiver in a telephone does.

Hearing aid technology incorporated the use of vacuum tubes in the early 1920's. This would allow a much more efficient method for amplifying sound. But still the early electrical hearing aids were far too unwieldy to be carried around easily. Many were as large and as heavy as a desk radio. But more importantly the development of the smaller more effective hearing aid was soon to be invented.

Smaller Batteries, Smaller Hearing Aids:

One of the first major changes in the history of the hearing aid was the miniaturization of the batteries. Previously batteries were large, heavy, and could not hold a charge for any length of time, this making the battery impractical for hearing aid use. In the early use of the hearing aid the hearing-impaired person had to wear a battery pack on their body. By the 1930s hearing aid technology had progressed such that hearing aids became portable.

The Transistor Changes Everything:

Yet to come was the most important event in the history of hearing aids completely changing hearing aid technology. This was the invention of the transistor in the 1950s . The transistor is simply a switch that has no moving parts and only two settings. One being the on and the other being the off position. By putting transistors together you can get incrementally larger combinations of on/off switches, the basis for binary code, and essentially a computer in its simplest form.

Additionally, a transistor's conductivity can be manipulated based on the purity of the silicon with which the transistor is made.Thus providing an infinite number of possibilities for which the transistor can be used. Silicon transistors allowed hearing aids to shrink in size so they could become "body aids". This eventually leading to hearing aid technology being available in a size we're familiar with today with aids that can be worn discretely behind the ear or even within the ear canal.

The Digital Age:

Digital hearing aid technology was in common use by the mid 1990's, allowing for more precise shaping of the sound into the wearer's ear. With digital circuitry, sound could be amplified or dampened as required by the hearing aid user. By this time programs were created that could be utilized depending upon the user’s location or needs. In turn allowing more amplification for quiet settings or specific amplification of certain frequencies in loud situations where the user could clearly hear speaking voices even when surrounded by other noises. Digital products also took advantage of compression technology, effectively eliminating the distortion of very loud sounds. This distortion being an annoying side effect that had plagued users throughout the history of hearing aids.

Today's Hearing Aid Technology.

We are still shaping the history of hearing aids, and hearing aid technology is constantly being updated. New technologies are being introduced allowing the user to be directly involved with the fitting of his or her hearing aids. Instead of basic prescriptions based on a user's audiogram, testing can be performed comparable to the optical testing done in an ophthalmologist's office, to hone the hearing aid's settings for the specific user. Now instead of a hearing aid user listening to a narrow band of sounds, making loudness judgements and filling out a questionnaire, hearing aid users are now able to modify their hearing aid settings to suit their needs.

Computer programming now enable the computer to deal with ambiguities that are built into some of current day hearing aids. This now allows us to customize settings to ensure the hearing aid output is constantly optimized to the listener's needs for every sound in every environment. Clinical studies show this new generation of hearing aid technology can provide consistently improved intelligibility of speech in quiet and noisy environments, more comfort for the user in the presence of loud sounds, greater audibility of soft sounds and improved sound quality over conventional amplification schemes.
This form of hearing aid technology is not offered by all manufacturers. Therefore it may be worth looking into as it can greatly improve a user's hearing when using the aid. Most hearing aid technicians keep up to date on all new technology and new hearing aids available. Newer hearing aids are also being offered with limited ear occlusion, making them nearly invisible and in some cases allowing the user's hearing to be further improved.

A new hearing aid technology known as adaptive dynamic range optimization is starting to become available from some manufacturers. This is one of the most significant changes in the recent history of hearing aids, as it is a major update from traditional compression circuits most often used with digital hearing aids. Adaptive dynamic range optimization allows the hearing aid to make constant adjustments to its algorithms using fuzzy logic. This new hearing aid technology delivers to the user a higher level of sound quality, eliminates echoing and eliminates louder nuisance sounds more readily.
The latest development of adaptive dynamic range optimization goes one step beyond what was originally offered. Some companies now offer an ultra-low delay product that delivers up to 32 channels which is a large increase over earlier products that only offered seven or eight. Some products in this new generation of hearing aids also incorporate a newer, adaptive directional microphone. This new hearing aid technology gives us a glimpse into what the future holds for those with hearing loss.

The Future of Hearing Aid Technology:

The future of hearing aids will bring extremely exciting new options for all hearing aid users. Transducers are getting smaller and at the same time circuitry is shrinking rapidly. Meaning that smaller increasingly more powerful hearing aids will be forth coming. The hearing aid user will find themselves more in control of their own hearing as well as becoming more involved with the fitting and adjusting of their hearing aids. Hearing aids have come a long way from the ear trumpet, but hearing aid technology is continuing to evolve with time and there's still a long way to go.