The history of hearing aid design and technology


Contributed by Debbie Clason, staff writer, Healthy Hearing

Necessity is the mother of invention, as the saying goes, and those who look back on the evolution of hearing aid design would most likely agree. Large, cumbersome hearing devices don’t mix well with this ever changing, multi-tasking world we live in — and thanks to major advances in technology, today’s devices are smaller, sleeker-looking and more proficient at mimicking the human sense of hearing than those that were first marketed more than 120 years ago. Let’s take a look at their metamorphosis.

Ear trumpets and conversation tubes

hearing aid history
This simple gesture inspired the early ear

trumpet hearing aids.

If a cupped hand can boost the volume of sound to your ear, just think what a long, cup-shaped funnel could do. That may have been the inspiration behind the invention of ear trumpets and conversation tubes, non-electric assistive listening devices that have been around since the middle of the 18th century. In fact, a page from Montgomery Ward’s 1894 catalog features illustrations for three different models of ear trumpets and ear tubes, one promising to “suit the most obstinate case of deafness.”

Of course, ear trumpets didn’t really amplify sound — they actually just collected it from the immediate surroundings and dialed it right into the ear canal. As humorous as the cartoon depictions of these devices now appear, they were relatively successful in improving the user’s ability to hear. Here’s why:

  • The cup-shaped design effectively limited background noise when sound was delivered directly into the device.
  • The long, angular trumpet and/or tubing provided a certain amount of personal space. You needed to stand beside a person using an ear trumpet, but you didn’t have to put your lips inches from his ear. Likewise, conversation tubes were made in different shapes and sizes in order to accommodate a variety of listening situations.
  • The devices were portable and didn’t need any special apparatus to make it work — such as batteries or cumbersome backpacks.

Body aids

Even though ear trumpets and conversation tubes were popular well into the 20th century, the invention of the carbon microphone at the turn of the 20th century ushered in a new hearing aid design.

  • Carbon hearing aids were the first electrical hearing aids. These devices used carbon granules packed in a cylinder to produce a scratchy sound which only benefited those with mild to moderate hearing loss. The part of the device which covered the ears resembled a headset, with wires that connected to a bulky battery and microphone the user would carry or attach to their clothing.
  • Vacuum tube hearing aids used carbon battery technology; however, smaller vacuum tubes (1 ½” to 1 ¾” long) amplified the output of the carbon hearing aid. These tubes made it possible for the hearing aid to fit inside a shirt pocket, even though they still needed two large batteries to power them.
  • Transistor hearing aids made their debut in the early 1950s after Bell Labs invented the transistor (1948). The single, smaller battery reduced the overall size of the hearing aid and provided prolonged battery life.

Ear-level hearing aids

Then along came the integrated circuit and hearing aid manufacturers found ways to miniaturize the process even further. The microchip paved the way for ear-level hearing aids — those which could now fit discreetly behind the ear. Placing the microphone at ear level helps simulate natural sound and for the first time, users could wear two devices and achieve bilateral hearing amplification. When the zinc-air battery appeared on the scene in the late 1970s, battery life doubled. Zinc-air batteries are now considered the industry standard, replacing their silver oxide and mercury predecessors.

In the past 60 years, hearing aid design has made its most dramatic changes, and now house powerful, miniaturized circuitry in comfortable and efficient models that are small and discreet. The following types of ear-level hearing aids each have their own benefits depending on the individuals severity of hearing loss, lifestyle and budget.

  • Behind-the-ear (BTE) – The first BTE made its debut in 1956. Now even smaller in size today, they still resemble the first models. The components for the microphone, receiver, amplifier and battery are housed in a crescent shaped compartment which fits snugly behind the ear. Tubing connects the device to an earmold which fits in the ear canal.
  • Receiver in the ear(RITE)/ Receiver in the canal (RIC) – You might think a hearing aid couldn’t get any smaller once technology allowed for the entire device to fit inside the ear canal, but you’d be wrong. Even this type of hearing aid has become progressively smaller and more effective since its origins in 1983. The first models protruded from the ear. Today’s models are often so small they are virtually invisible to others standing beside you.
  • Completely in the Canal (CIC) and Invisible in Canal (IIC) hearing aids first appeared in 1993. These custom-made devices are created from ear molds of each individual’s ear canal, so they fit perfectly and deliver maximum benefit. Their size and location make them virtually undetectable to others, one of the main features which makes them so desirable among users.

The best hearing aid design?

Today’s hearing aids come in all shapes, sizes and colors with features as varied as the millions of users who now wear them. Which one is best? Undoubtedly, the one that has been selected for you by a hearing healthcare professional. Together you can identify the manufacturer and model that’s best for you depending upon the severity of your hearing loss, the listening situations you encounter on a daily basis and what you’re able to pay for hearing devices. Ready to start your journey to better hearing health? It all begins with a hearing evaluation. Visit our directory of hearing healthcare professionals to find one in your community.


Source link