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Concealed Hearing Devices of the 20th Century

During the 20th century, aids for hearing evolved from mechanical to electrical devices. Using an external power source, sounds could now be made louder than was possible with earlier mechanical designs. Consequently, hearing aids were able to provide amplification of sound to those even with severe to profound hearing loss. Coincident with the change from mechanical to electrical designs were advances in technology that paved the way for innovative designs of concealed hearing aids and allowed for manufacture of hearing aids at more affordable prices.

Early Electrical Hearing Aids were based on telephone technology invented by Alexander Graham Bell in the late 19th century. A carbon-granule microphone in combination with a battery could produce sound at an earphone at levels greater than those possible with mechanical devices. Carbon hearing aids, while effective for moderate losses, had limited amplification and poor-to-moderate sound fidelity.

The introduction of vacuum tubes in the early 1920s was a major technological step in the evolution of electrical hearing aids. Vacuum tubes provided a much more efficient method of amplifying electrical signals. This efficiency translated into greater acoustic gain and hence yielded greater benefit for hard of hearing and deaf users. The early vacuum tubes were very large with two batteries required for power.

During the 1930s and 40s, miniaturization of vacuum tubes allowed manufacturers to develop body-worn designs that housed vacuum tubes and microphones within a single unit, which allowed for portability. However these early body-worn hearing aids were cumbersome and still required use of batteries not housed within the hearing aid. Wires were required to connect the batteries and the earpiece to the microphone/amplifier unit.

To power a vacuum tube hearing aid, two batteries were needed: an ‘A’ battery to warm the filament in the vacuum tube and a ‘B’ battery to amplify the sound. The batteries were at least as large as the other components of the hearing aid and weighed up to 2.5 pounds. Users wore batteries in cumbersome battery holders under their clothes or in pockets with straps, and multiple thick cords connected the batteries to the earpiece and microphone/amplifier unit.

Battery Harness, ca. 1940

Courtesy of Sonotone Sonotone recommendations for wearing hearing aid and batteries Manufacturers included instructions in user manuals for wearing of batteries. These illustrations come from the manual for the Sonotone model 700 hearing aid, introduced in the mid-1940s. On women, the large, standard batteries could be worn in a harness (“Battery Garment”) under the arm, beneath the bust, or on the leg.

By 1947 advancements in battery technology led to even more dramatic size reductions. Now, the microphone, amplifier, and batteries could be packaged in one unit with a single cord to the earpiece.

Hearing aids that fit into a shirt pocket or clipped to a lapel were the first all-wearable styles, housing the batteries, small vacuum tubes, amplifier and microphone into the same casing. These devices were usually directed toward men, who often wore suits, ties, and shirts with pockets which allowed for concealment. Pocket aids included a tie or pocket clip with an insignia to camouflage the microphone.

Tie Clip Models Hearing aids that clipped to a tie or a lapel were among the first all-wearable models of hearing aids.

Hal-Hen Hearing Aid Klip The Hal-Hen Men's Hearing Aid Klip was designed to fasten to two buttons on a man’s shirt. The elastic strap securely held a hearing aid in place under a tie. © Hal-Hen Company, Inc.

This photograph demonstrates how a “pocket aid” could be discreetly tucked into one’s pocket.

Maico Model J “Top Secret,” 1950 This small hearing aid measured just 1-7/8 inches by 2-7/8 inches and could be easily concealed in a pocket. The microphone was on top of the device, thus eliminating the unwanted noise from the microphone rubbing against clothing.

	Decorative insignia to disguise microphones
	Sonotone’s brochure for the Model 940 illustrated a number of decorations that could be used to decorate and disguise the outside of a microphone. Examples given included “fraternal, service club, Legion, war service insignia, union or church buttons, or any favorite ornament having a flat back.”
Courtesy of Sonotone

Among the more ingenious attempts at concealment of hearing aids were watches and pens.

	Telex Fountain “Pen”
	The Telex 300 was produced in 1950 and, according to the ad, was a “precedent shattering” model “to help keep your hearing loss a secret from all the world.”
Reprinted from The Hearing Journal 50 (11) 1997, p.43, with the permission of Lippincott, Williams and Wilkins

For women, hair is a natural place to conceal a hearing aid and hearing aid manufacturers of the 20th century, like those of the 19th century, designed a variety of models that could be concealed within hair. Such devices included barrettes, scarves and hats.

	Hearing aid manufacturers also included directions on how to wear your hearing aid while at the beach or wearing a halter neckline.
Courtesy of Sonotone

This wig patent from 1934 represents one of the few designs for non-electrical hearing devices of the 20th century and was used to disguise hearing trumpets.

Another unusual patent for hair is this patent from 1957 that allowed for women to wear an ear trumpet device while using a hair dryer at the beauty shop.

In the 1950s, many men and women would not dream of leaving the house without being smartly attired with several items of ornamental jewelry. In this era, hearing aid earpieces were often disguised as earrings, microphones made to resemble brooches or tie clips, and cords concealed within women’s necklaces.

 

Decorative insignia pins for women, as seen in these advertisements for “SonoCharms,” concealed hearing aid microphones.

 

 

Courtesy of Sonotone

Courtesy of Sonotone

“Smartly worn” hearing aids and devices with cosmetic appeal were marketed during the mid 20th century. Manufacturers claimed that their devices were virtually unnoticeable, discreet, or invisible and that “no one will know you are deaf.” Hearing devices were becoming smaller, their batteries were smaller and lasted longer, and their power was increasing.

Courtesy of Sonotone

Courtesy of Beltone Electronics Corporation

Courtesy of Telex Communications, Inc.

The development of the transistor in the late 1940s enabled once-cumbersome hearing aids to be streamlined into single units practical for everyday use. What could be more practical than incorporating a hearing aid – or two – into eyeglasses? The first eyeglass model was introduced in the United States in 1954. By 1959, they accounted for approximately 50% of the market.

	Radio Hearing Aid
	One ingenious design of a camouflaged hearing aid that was possible with the development of the transistor was a radio. As seen here in the photo, a hearing aid is disguised as transistor radio, the 1960s equivalent of today's iPod.
© Reprinted with permission from Arnoud Beem

The behind-the-ear hearing aid (BTE), first introduced in the late 1950s, was an ideal means of concealing a hearing aid – it was worn discreetly behind the ear and underneath the hair, with a custom-made earmold. The BTE incorporated all components of a hearing aid into a single, streamlined unit including the batteries. Within a few years of the introduction of the BTE, the BTE overtook the eyeglass hearing aid model in hearing aid sales in the United States.

Zenith “Diplomat,” 1956 Zenith’s first BTE (behind-the-ear) model hearing aid was the Diplomat, introduced in 1956. This four-transistor aid has an external receiver and microphone openings on both sides of the flesh-colored plastic case. This model also was available in light gray. The Diplomat weighed less than an ounce. Advertisements described the Diplomat as “tiny, feather-light, tinted, and contoured to fit snugly and comfortably right at the ear!”

This image shows the internal components of a BTE (behind-the-ear) model.

In-the-ear (ITE) and in the canal (ITC) hearing aids were introduced in the late 1950s and early 1960s and even smaller completely-in-the-canal (CIC) hearing aids entered the market in the 1980s and 1990s. These models provided more opportunity for concealment with acoustic benefit for many users.

 

By 1996, hearing devices housing all hearing aid components completely within a custom-made earmold represented about 80% of all United States hearing aid sales. New features such as directional microphones, flexible digital programming and adaptive filtering provide users with the best of both worlds – an effective hearing aid that is also virtually unnoticeable.

	Phonak’s Claro system, 2000
	Phonak’s Claro system of hearing aids can be remotely controlled by both the SoundPilot and WatchPilot systems. Pictured are a BTE aid (center, bottom) and the hand-held SoundPilot remote control (right) and the WatchPilot remote control (top, center). Both systems remotely control all instrument functions of the hearing aid. The WatchPilot doubles as a Swiss quality wrist-watch.

In the 1990s, manufacturers began to design hearing aids to be noticed as jeweled adornments and works of art. Hearing aids are made with stainless steel, brightly colored casings, and even encrusted with semi-precious stones.

Earmolds are also available in many colors and with whimsical decoration such as polka dots and frogs.