From ear trumpets to transister hearing aids in 1953
In the 1960s it was estimated that the United States had approximately 40 companies identifying themselves as hearing aid manufacturers. The greatest number were located in Minneapolis, MN and as a result, Minneapolis/St. Paul was often identified as the hearing aid capital of the world, and still today, as the hearing aid capital of the United States.
And although Minneapolis/St. Paul was not the city of origin of hearing aid manufacturing, its history and contribution to the industry was, and continues to be, of interest. A series of events combined to bring about this initiative. Some of these events were concurrent.
Event 1
The introduction of the vacuum tube in the mid 1930s brought about engineering advances in portable hearing aids that rapidly replaced carbon type hearing aids. The first use of these appeared in England in 1934-35 with credit given to either Amplivox or Multitone. In the United States, the first portable vacuum tube hearing aid is credited to Ralph Allison in 1936 in Minneapolis, and by Ray-O-Vac Battery Company in 1937.{{1}} [[1]] The Hearing Aid: Its Operation and Development, National Hearing Aid Society, 1970.[[1]] Ray-O-Vac electronics research engineer Arthur Wengel, applied for a vacuum hearing aid patent in 1937, which was granted in 1940. However, only a small number of instruments were manufactured under the name of Stanlyphone in 1937 and 1938, and the project was abandoned after the first year. These first vacuum instruments weighed in at about 2.5 lbs.{{2}} [[2]] 50 Years of Hearing Health Care, 1940-1990, Skafte, M., Hearing Instruments,1990; 14, 16.[[2]]
Event 2
In 1933-34, a student at the University of Minnesota, Ralph Allison, was asked to build a hearing aid for a patient of Dr. Paul Dwan, a Professor in the University Medical School. Dr. Dwan had read of the vacuum tube innovations related to hearing amplification. The result was a hand-held vacuum tube device assembled in Allison’s basement and which was sold to a limited number of people in the area. Allison founded a company called Audio Development Company in 1935, but primarily to build a new test device called the audiometer, not hearing aids. In 1936 Allison was joined by fellow engineer Walt Lehnert, and together they diversified the company’s product line from audiometers to include amplifiers and transformers for the broadcast industry, and changed the name to ADC Telecommunications, Inc.{{3}} [[3]] 50 Years of Hearing Health Care, 1940-1990, Skafte, M., Hearing Instruments,1990; 14, 16.[[3]]
Figure 1. Ralph Allison developed the first portable vacuum tube hearing aid.
Event 3
Another part of the Twin Cities hearing aid development had its roots in a New York hearing aid company called Sonotone. Allen Hempel and Leland Watson worked for the Sonotone branch in the Twin Cities; Hempel as upper Midwest sales representative, and Watson as sales manager for the local business. Both left the company to start their own businesses in the mid-1930s – Hempel in hearing aids, and Watson in audiometers. (Note: There is confusion as to whether Hampel worked for Acousticon, Auricon, or Sonotone. History suggests that Hempel may have started with Acousticon, dabbled with Auricon, and then switched to Sonotone).
Allen Hempel was a business machines salesman in Minnesota in the 1920s and early 1930s. He made calls on companies selling business tools and devices and after a troublesome meeting with a company manager who had a hearing loss, he signed on with Auricon and Acousticon to sell hearing aids, and then with Sonotone. He became aware of Allison’s hearing aid product and made arrangements to market this “portable” unit nationally in 1936 (Figure 2). He and Allison formed a company in St. Paul, MN, Telex Products Co., (then moved it to 4753 France Ave. S. in Minneapolis) with the hearing aid itself called Telex. The first actually wearable (as opposed to hand held) vacuum tube hearing aid was developed by Telex in 1937 (no photograph, but it still required an A and B battery pack). It was rectangular in shape, had four vacuum tubes (British rather than US because they required less power), a crystal microphone, and slide fingertip tone-pitch and volume controls. The aid could be purchased with a telephone connector and a power unit to connect the hearing aid to AC house current. From this hearing aid, the hearing aid industry was realistically born.
Figure 2. First portable, vacuum tube hearing aid designed and made by Ralph Allison for Telex - 1936. (Staab Slide Collection).
Leland A. Watson (Figure 3) was not only a successful hearing aid salesman starting in 1933 and working with Allen Hempel at Sonotone, he was also an innovator. As the son of a Minneapolis ear physician, he recognized early that he could develop a better hearing testing product than the one he was selling. He knew that early audiometers were complicated, requiring intricate calculations to measure a patient’s hearing loss. Realizing the need for clinicians like his father to have an easy-to-use audiometer, a term he coined, Watson established Medical Acoustics Instruments Company (later shortened to MAICO) in 1937 in a one-room office laboratory. He eventually developed the Maico D5, the first audiometer to incorporate a “zero reference level” which made it possible for the first time to accurately measure hearing loss. The D5 subsequently became the first audiometer recognized by the American Medical Association (AMA) and the National Bureau of Standards (now known as the National Institute of Standards and Technology). In 1938, Maico produced its first hearing aid. Watson died in a Northwest airline crash in 1960 at the age of 52.
Figure 3. Leland Alfred Watson - 1907-1960.
Event 4
Following WWII, Minnesota native triple flying Ace Kenneth Dahlberg (Figure 4), after attending a party and after meeting Allen Hempel, went to work for Hempel at Telex as one of his assistants, specializing in international sales, rather than going back to his pre-war work in the hotel business. {{4}} [[4]] One Step Forward Review, Al Zdon, https://www.mnlegion.org/paper/html/dahlberg.html.[[4]] He left Telex in 1948 to form Dahlberg, Inc. and the Miracle Ear subsidiary, along with his brother. Other hearing aid manufacturing companies founded in the Twin Cities up to the 1980s were Goldentone USA, Inc. 1942; Qualitone, 1954; Starkey, 1971; Argosy, 1979; 3M in 1980; and Micro-Tech, 1986. Additionally, there were numerous other hearing aid manufacturing companies, earmold laboratories, and other support companies that sprang from these. Skills learned from working with the previously-mentioned companies allowed for fairly easy transition into new company formations, especially with the introduction of custom-molded hearing aids, which reduced the investment capital for start-up companies. And because a start-up manufacturing facility did not have to be relocated, there was no reason to move from the city where skilled hearing aid assemblers and other personnel already lived.
Figure 4. Pilot Ken Dalhberg helps his ground crew load ammunition into his aircraft. Each band of machine gun ammo was nine yards long, and thus the expression, "the whole nine yards." https://www.mnlegion.org/paper/html/dahlberg.html
In closing, there is no intention in this blog to identify all of the offshoot hearing aid and related companies that emerged in the Twin Cities to make it, at one time, the hearing aid capital of the world. But, suffice it to say that the origin was related to two companies – Telex and Maico. Sadly, neither of these companies exist today as hearing aid companies. Telex was acquired by the Bosch Group, a German supplier of communication systems and one of the world’s largest privately held companies in 2006. The Telex brand now includes aviation headsets, wireless intercom systems, and other communications products. Since 1995, Maico has been owned by Danish firm William Demant Holding, which also owns Oticon. The Maico brand manufacturers primarily hearing test equipment.
