Early Mechanical Hearing Devices
The Hearing Journal: August 2019 - Volume 72 - Issue 8 - p 8,9
doi: 10.1097/01.HJ.0000579564.45174.32
Hearing Aids Development
Over the years, hearing devices have taken many shapes and forms. The first article of this series, published in The Hearing Journal’s April 2019 issue, discussed the earliest of these mechanical devices—the ”cupped” human hand, which provides an acoustic gain of up to 7 to 17 dB, benefiting listeners with slight-to-mild hearing loss. Other early hearing devices were animal horns or shells. It is likely that such natural and easily found implements were used initially for the transmittal of sound. Alexander the Great (356-323 BC) reportedly used a sound-amplifying suspended animal horn to call together huntsmen or soldiers from across a large area.1 In his dissertation titled Tuba Stentorea, Max A. Goldstein, MD, best known for founding the Central Institute for the Deaf, listed devices from the early 18th century, including an illustration of a speaking trumpet used to transmit voices from one sea vessel to another. However, details about the transition in the use of natural implements from amplifying sound transmission (from the talker) to amplifying sound reception (to the listener) remain unknown. Credit may be due to ingenious deaf individuals. As Mudry and Dodelé speculated, “It is quite probable that deaf people of ancient times and the Middle Ages must have thought of placing the mouthpiece of a horn or a bugle to their ear for purposes of amplification.”2
17TH TO 19TH CENTURY DEVICES
Mechanical devices designed specifically for hearing appeared in written documents from the 1600s. Sir Francis Bacon, in Sylva Sylvarum: A Natural History published posthumously in 1627, described an instrument to aid hearing and compared this instrument to “ear spectacles.” In Geometria, published in 1640, Pietro Maria Amiani described a device for those with hearing impairment; also noted were the mathematical details and the use of an ear trumpet to facilitate hearing.3
Early mechanical devices were often works of art with repoussé work, engravings, embossing, paint, and intricate grillwork. Materials included brass, enamel, silver, and gold, and decorations included flowers, birds, and dragons. As a result of the rarity and cost of the devices, their use was limited to royalty and the elite. For example, a collapsible conical ear trumpet called the Reynolds Trumpet was initially built for the English painter, Sir Joshua Reynolds (1723-1792). German inventor Johann Nepomuk Mälzel (1772-1838) made an ear trumpet that was used by Beethoven around 1812. The ear trumpet used by English author Harriet Martineau (1802-1876) was popularized and eventually named after her, becoming the Martineau Hearing Horn.
In the early 19th century, mechanical devices became commercially available, and hence, more widespread. London-based companies F.C. Rein (founded in 1800) and Thomas Hawksley (founded 1869) were among the earliest known commercial manufacturers of hearing devices. Both manufacturers produced a variety of mechanical hearing devices—trumpets, domes, conversation tubes, ear cornets, and auricles.
AN ACOUSTIC CHAIR?
One of the more unusual mechanical hearing devices was Curtis’ Acoustic Chair. It was designed by British aurist and oculist John Harrison Curtis (1778-1860), who established the Royal Dispensary for Diseases of the Ear in 1816, the first hospital devoted to ear diseases. The sixth edition of Curtis’ A Treatise on the Physiology and Pathology of the Ear(1836) includes an illustration of the Acoustic Chair equipped with a large trumpet along one side to transmit sound to the chair-sitter's ear (Fig. 1). Curtis described the chair as follows:
“My Acoustic Chair is so constructed, that, by means of additional tubes, &c., the person seated in it may hear distinctly, while sitting perfectly at ease, whatever transpires in any apartment from which the pipes are carried to the chair; being an improved application of the principles of the speaking pipes now in general use. It is, moreover, a very comfortable and elegant piece of furniture.”4
CONCEALMENT AND COST
While the devices have changed over the years, human vanity has not. From the outset, concealment was highlighted in the design and advertisement of these commercially available mechanical hearing devices. Some trumpets or domes contained ribbons, lace, or leather to disguise their purpose. One brand of trumpet was described as able to be partially concealed by the hand, and illustrations demonstrated how to hold the devices in an unobtrusive way. In their catalog description, Thomas Hawksley compared cornet hearing devices to works of art, while also mentioning the devices’ concealment:
“… these self-supporting cornets may be rendered works of art by being tastefully decorated with repoussé work, engraving or embossing, and the sound collector covered by a grille. Parts may be enameled a flesh tint or to match the color of the hair… for ladies they afford the most ready means of concealment, as the hair or cap may be easily arranged to hide them… ”5
Arguably, the most ingenious of the mechanical hearing devices produced in the 19th century were created for concealment or camouflage. Devices were made to be hidden in a pocket, in a beard, or within the hat or hair of the user via a headband, etc. Devices were disguised as plate holders, flower vases, handbags, binoculars, hand fans (Fig. 2), umbrellas, opera glasses, water canteens, and books for use during chapel services.
Designs for concealment, however, came with a price. Compared with other devices of the time that were not designed for disguise or concealment, these concealed or camouflaged devices were suitable only for those with the mildest of hearing loss. For example, the Aurolese Phone, produced by F.C. Rein in 1802, resembled a floral-decorated headband and could provide gains of about 5 to 10 dB. This amount of gain is similar to or slightly less than that achieved by the cupped hand and would benefit listeners with very slight-to-mild hearing loss.6,7 By contrast, the London Dome type of ear trumpet (manufactured in 1850) was large, bulky, and heavy; it offered no pretense of being disguised or hidden. But the London Dome could provide an acoustic gain of about 10-27 dB in the frequency range most critical to speech understanding (300 to 3,000 Hz).8 Similarly, the obtrusive Elliptical Opening Trumpet, manufactured by Hawksley in 1875, produced an acoustic gain of 32 dB at 600 Hz. Thus, although devices that provided strong acoustical gain (up to 30 dB) were manufactured, the concealment aspect of camouflaged devices appealed to many users. According to Stephens, the majority of the population wanted, and would pay for, increasingly inconspicuous devices even if they were of little benefit to their hearing.9
The cost of 19th century hearing devices ranged from $1.27 to $38. For example, from the Hawksley Catalogue, a device disguised as a walking stick cost $3.82, one for hidden use within a beard cost $6.30, and the Hawksley table-top receptor listed for $38. At the turn of the 20th century, 59 percent of British adult men earned less than 25 shillings per week (or $1.58 today).10 As such, these devices’ costs were equivalent to the wages earned from working for one week to six months, and their purchase would have been beyond the means of most people. Consequently, the use of these mechanical hearing devices was generally confined to the middle- to upper-class members of society.
As the 20th century unfolded, technological developments in amplifiers and electronics paved the way for hearing devices that could provide stronger acoustic gain and sophisticated sound processing. Humans, though, may not have changed as much as technology has. Style does not necessarily give way to functionality. Manufacturers of hearing devices, past and present, share the goal of producing visually pleasing, unobtrusive devices while providing acoustical benefit.
Stay tuned for the final installment of this series, which will focus on 20th Century devices as well as the marketing and advertising strategies used by hearing aid manufacturers.
REFERENCES
1. Goldstein MA. Problems of the Deaf. Saint Louis, MO : Laryngoscope Press; 1933.
2. Mudry A, Dodelé L. History of the technological development of air conduction hearing aids. J Laryngol Otol. 2000;114(6):418-423. doi:10.1258/0022215001905977.
3. Berger K. The Hearing Aid: Its Operation and Development, 3rd ed. Livonia, MI : National Hearing Aid Society; 1984.
4. Curtis J. A Treatise on the Physiology and Pathology of the Ear, 6th ed. London : Longman, Rees, Orme, Brown, Green, and Longman; 1836.
5. Hawksley T. Catalogue of Otoacoustical Instruments to Aid the Deaf, 3rd ed. London : John Bale; 1895.
6. Carraway M. Development of a Historic Hearing Devices Exhibit. 2001. Independent Studies and Capstones. Paper 279. Program in Audiology and Communication Sciences, Washington University School of Medicine. http://digitalcommons.wustl.edu/pacs_capstones/279. Accessed February 7, 2019.
7. Uchanski RM, Sarli CC. The ‘cupped hand’: legacy of the first hearing aid. Hearing Journal. 2019;72(4):8-9. doi:10.1097/01.HJ.0000557743.90033.5c.
8. Sarli CC, Uchanski RM, et al. 19th-century camouflaged mechanical hearing devices. Otol Neurotol. 2003 Jul;24(4):691-8.
9. Stephens SD, Goodwin JC. Non-Electric aids to hearing: a short history. Audiology. 1984;23(2):215-240. doi:10.3109/00206098409072836.
10. Mitchell S. Victorian Britain: An Encyclopedia. New York: Garland; 1988.
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