In 1965, Harford and Barry were credited for the first accessible published description of across-head fitting1.  It was called the CROS (Contralateral Routing of Offside Signals).  Harford and Barry did acknowledge, however, that Wullstein and Wigand had published results on an almost identical across-head arrangement three years earlier2.  The Wullstein and Wigand work has seldom been quoted in related literature in the US, perhaps because it was written in German3.  But, were these the first CROS hearing aids?


Eyeglass Hearing Aids

Interestingly, even prior to Wullstein and Wigand’s publication in 1962, across-head hearing aid fittings were common.  This concept was incorporated into the first eyeglass hearing aids.  This was even prior to Fowler (1960) suggesting that for total monaural hearing loss, that a microphone could be placed on the bad ear side and use a bone-conduction vibrator at the good ear4.  (Ken Berger reported that H.J. Salomon et al. in 1965 filed a patent that essentially followed Fowler’s bone vibrator coupled to an off-side microphone – patent #3,183,312).  

At least since 1954, a number of hearing aid manufacturers produced eyeglass hearing aids in which both temples were needed to achieve across-head hearing.  This was primarily due to the size of components, requiring that some components be placed in each temple, and the two sides hard wired to each other.  Eyeglass hearing aids were common at the time as evidenced by the number of companies that made such units, and are listed in the following section.  This information on companies and the designation of two-temple requirements for such aids was compiled from Berger’s book on hearing aids3.

 

Company and Year in Which Across-Head Eyeglass Hearing Aids Were Introduced

  • Akumed MGH Glasses – 1954
  • Acousticon Model A-235 – 1956
  • Amplivox Model SA – 1956
  • Ardente Acoustic Laboratories, LTD Model A – 1955
  • Auditron (Globe) Model T12 – 1959
  • Audivox Model “Spectacular” – 1956
  • Aurex Model A400 – 1955
  • Beltone Model Virtuoso – 1958
  • Bommer Model FM – 1956
  • Robert Bosch Elekrtronik Model Hörbrille – 1957
  • Danavox International Glasses Model – 1956
  • Deutsche Akustik-Gesellschaft Glasses Model – 1958
  • Dicton Høreteknik Glasses Model – 1958
  • The Dynaphone Co. DynaGlasses Model – 1956
  • AG Für Elektro-Akustik Model Visaton – 1956
  • Fortiphone LTD Model Spectette – 1956
  • Gem Ear Phone Co. Glasses Model – 1957
  • Linke-Hörgeräte Glasses Model – 1956
  • Magnatone Corp. Model M1 – 1956
  • Maico Electronics Model AF Transist-Ear – 1958
  • V/O Medexport Model CO-2 – 1958
  • Micro-Elektrik Ltd. Model B/05 – 1956
  • Microtone Co. Model Vision-Ear Bone-Conduction glasses – 1954
  • Otarion Electronics Inc. Model L.10 (Listener) – 1954
  • Oticon Eyeglass Model – 1956
  • Otoacustica Electronic Products Model Gamma (Telescope) – 1961
  • Paravox Hearing Aid Co. Model I-G (I-Glas) – 1955
  • N.V. Philips Gloeilampenfabrieken Model KL6100 – 1959
  • Polyfon Hearing Aids Ltd. Model Optic Ear – 1958
  • Radioear Corp. Model Stereo – 1958
  • Rexton Model H-570 Glasses – 1960
  • Siemens A.G. Glasses Model – 1957
  • Skandiavox Model 60T – 1958
  • Telex Corp. Model #44 – 1958
  • Toepholm & Westermann A/S Model Sight-N-Sound Glasses – 1959
  • Trans-Audio Co., Inc. Model Twin Temples – 1958
  • Unex Laboratories, Inc. Model VE (Vision Ear) – 1955
  • Wendton Model WT800 – 1955

An example of an across-head eyeglass hearing aid is provided in Figure 1.  This is from the author’s collection and shows a Dicton unit from 1958.  What follows is a report on this device to assist in explaining how the across-head eyeglass hearing aid was designed.

Author’s Note: What most hearing professionals do not realize is that during the mid 1950s into the early 1970s, eyeglass hearing aids were very much the fitting style.  They were the “new” technology.  In fact, according to Lybarger, they preceded behind-the-ear hearing aids in development history.  (More on this in a later post).

 

Dicton Høreteknik Model C, Year = 1958

The Dicton eyeglass hearing aid was designed to take sound from one side of the head via a microphone pickup, and transferring sound to the contralateral ear using a wired arrangement through the eyeglass frame and temples to the ear. This was powered with a 625 cell and used an Oticon receiver housed in the off-side module.  The hearing aid was manufactured in Copenhagen, Denmark by J. Laurberg Christianson with Skandiavox.  It was distributed in the United States by Omega Electronics (Jose Manzini in New Orleans, LA) and in England by Leyton Instrument Company.

Figure 1.  Dicton across-head hearing aid from 1958.  The microphone is on one side, along with the amplifier and power supply, and then wired through the eyeglass temple and frame to the opposite side to the hearing aid receiver where the sound is directed to the ear through plastic tubing to an earpiece.  (From Staab Collection).

Figure 2.  Microphone, power supply, volume control, and amplifier side shown closest.  The two small slits are the microphone opening.  The battery compartment is open to show its position.  It used a 625 cell.  The volume control is on the lower back and upon turning it, does not suggest that the volume control also has an ON/OFF switch.  There were no other controls.  The far image is the other side of the eyeglass hearing aid.  That portion contained primarily the receiver.  Sound was delivered to the ear through a polyethylene flexible tube ending in some kind of ear piece.

The remainder of this post is to show this across-head hearing aid in some detail because there seems to be little information available on such early across-head eyeglass hearing aids, even though they were quite popular.

Figure 3.  The wiring routing the signal from the microphone/amplifier side is fitted in a groove cut into both eyeglass temples.  The plate (identified by the two screws) where the wire is hidden served also to store excess wire when the temple is shortened.  No rewiring was required.

Figure 4. This image shows the wiring through the hinge connection and temple length adjustment.  The temple was designed for 4 length adjustments down to 4 and ¼ inches.  The screws on the metal portion were moved to one of the 4 pre-drilled and threaded hole options and that part of the temple overlapping the front of the eyeglass was cut off.

Figure 5.  Wiring attached to the back of the eyeglass frames.

 

Comparison to Later Eyeglass CROS Hearing Aids

A comparison of the Dicton to a later eyeglass CROS hearing aid (Maico Transist Ear, Year = about 1970) is shown in Figure 6.

 

Figure 6.  A Maico Transist Ear (top, about 1970 and Dicton (bottom,1958).  Aside from size resulting from components, the Dicton had its electronics all in the paddles, with some components in each paddle.  The Maico had its amplification forward of that part of the temple that fit over the ear.  The volume control wheel is seen at the bottom of the aid, and forward.  The microphone remained in the paddle, as identified by the small whitish dot.  Because this was a CROS hearing aid, the receiver is in the opposite ear temple.  Wiring through the frame was often placed in the groove where the glass fits into the frame (Figure 7).

Figure 7.  Later models of CROS eyeglass hearing aids used a wire arrangement very similar to that of the Dicton unit.  Some dispensers grooved the back of the top of the frame and placed the wires into that groove and covered it with some kind of sealer.  At other times, an attempt was made to place the wires in the groove for the glass in the eyeglass frame.  The metal piece that the temple slides through was used to determine the temple length.

First Non Across-Head Eyeglass Hearing Aid

In fact, it was not until 1956 that the first eyeglass temple hearing aid was made that was not an across-head hearing aid.  That unit was the Audivox (successor of Western Electric) “Spectacular.”  It was a three transistor hearing aid and used a RM400 battery as its power supply (Figure 8 and 9).

Figure 8.  The first eyeglass hearing aid that did not use an across-head arrangement, but placed all components in one temple.  This was the Audivox “Spectacular” introduced in 1956.

Figure 9.  Images from the inside (top) and below (bottom) providing additional views of the locations of components, all in a single temple.

References

  1. Harford, E., & Barry, J. (1965). A rehabilitative approach to the problem of unilateral hearing impairment: the contralateral routing of signals (CROS). Journal of Speech and Hearing Disorders, 30, 121-138.
  2. Wullstein, H.L. and Wigand, M.E. (1962).  Über Hörhilfe zum Beidseitigen Hören für Einseitig Ertaubte und ihre Voraussetzungen (A hearing aid for single ear deafness and its requirements).  Acta Otolaryngologica, 54, 1962, 136-142.
  3. Berger, K. (1970). The Hearing Aid and its Development.  National Hearing Aid Society, Livonia, MI.
  4. Fowler, E. P. (1960). Bilateral hearing aids for monaural total deafness: a suggestion for better hearing.  Archives of Otolaryngology, 72, 1960, 57-58.

This post is a continuation of an attempt to archive some historical events related to hearing aids – that of the auriculostomy.  As reported in a previous post, the auriculostomy may have been the first surgical involvement in the fitting of an electrical hearing aid.   It provided an alternate approach to the application of corrective amplification involving ear-level hearing aids and involved minor surgical intervention1.  The auriculostomy hearing aid was invented by Charles Strzalkowski, an innovative and creative hearing aid dispenser in Milwaukee, Wisconsin, in 1975.  While the surgical procedure was called the auriculostomy, that term had become to identify the complete procedure, including the hearing aid (Telex Model 90), which was called the Auriculostomy Hearing Aid. 

 

Last week’s post briefly described the surgical procedure, and also described the advantages driving this technology.  This post describes the procedure, alone with the types of questions commonly asked.  This information is taken essentially directly from a brochure published in 19742.

 

 

Auriculostomy Procedures

Figure 1.  Front of auricle (concha cavum area) and posterior auricle markings with methylene blue to identify the site of the opening in the auricle to be.

Following otoscopic evaluation of the external auditory canal, and management of cerumen that might potentially interfere with the finished product, an antiseptic solution was applied to the auricle and to the external auditory canal, and then dried with sterile cotton applicators.

After this skin preparation, a fine wooden applicator dipped in methylene blue was used to mark the site of the opening to be.  This opening was in direct line with the external auditory canal, both from an anterior and posterior approximation (Figure 1).

Figure 2.  A local anesthetic was injected subcutaneously at the previously marked sites, both anteriorly and posteriorly.

A local anesthetic was injected subcutaneously at the previously marked sites, both anteriorly and posteriorly (Figure 2).  A sufficient amount of anesthesia was injected with a #26 needle about ½ to ¾ inches long, directly under the skin to form a wheel about 7 to 8 mm in diameter.

After the anesthetic was well-established, the perforation procedure commenced, using a specially designed and sharpened stainless steel punch 4 mm in diameter.  The instrument was lined up with the anterior and posterior markings previously made with the methylene blue, and closed tightly (Figure 3).

Figure 3.  Auriculostomy surgical tool punch (left), and in action (right), creating the auriculostomy hole in the concha cavum.

The instrument punch was held in place for a short time to help with hemostasis.  The tool removed a neat circular piece of epithelium perichondrium and cartilage, having passed through the concha on both sides.  The slight amount of bleeding was readily controlled by pressure and cotton tip applicators dipped in epinephrine hydrochloride, one to one thousand, and cleansed.

Figure 4.  Enlarged portion of metal pin through the Auriculostomy opening to which earmold impression material will attach to assist in proper lining up of the hearing aid processor connection to the external auditory canal.

After all bleeding had stopped, the ear was cleaned and a small cotton block was placed in the ear canal in preparation for the taking of an earmold impression.

A metal pin (Figure 4) was inserted into the auriculostomy for the earmold impression material to have something for form around and attach to.  This was necessary so that the finished canal earmold would be properly aligned with the auriculostomy opening.

Earmold impression material was then inserted into the external auditory canal, and also into the concha, helix inside border, etc. in order to obtain a complete impression of the anterior auricle.  The impression material was to also enclose the metal pin (Figure 5).  Following setup by the impression material, the metal pin that passed through the auriculostomy is unscrewed, and the ear impression is removed from the ear.  The metal portion remaining in the earmold impression was required by the earmold laboratory for the proper alignment of the final canal mold to the auriculostomy.  (Editor’s comment.  The final version modified the electrical connection of the hearing aid processor behind the ear to the receiver at the opening of the ear canal so that it was less visible (comparisons in Figure 6), and as a result, the exact alignment of the auriculostomy to the ear canal was no longer required.

Figure 5.  Metal pin through the fenestra unscrewed from its base encapsulated within the earmold impression to allow removal of the earmold impression.

Figure 6.  Changes for the initial version (left) to the final version of the auriculostomy (right) fitting for a BTE hearing aid.  Going from a direct plug-in to the earmold to an indirect route, allowed for improved cosmetics.  It also rendered the positioning of the fenestra in the earmold less important.

 

 

The auriculostomy was then inspected and cleansed with an antiseptic solution, and an hydrochloride of marfanil (5%) was sprinkled over the area.

A plastic pin (about 3 mm in diameter), having a collared end was inserted into the opening.  The pin had a narrower diameter than the auriculostomy opening (fenestra) to allow the skin to epithelize, and to prevent any slight swelling discomfort (Figure 7).  The pin was held in place using adhesive tape over cotton, and to assist in healing.

Figure 7.  Components/steps used for the finished product.  1) Ear impression with metal collar and metal pin screwed into it.  2) Ear impression investment.  3)  Plastic pin used to keep the fenestra open during the healing process and time wait for the finished product.  4)  Receiver to be placed in the outer portion of the canal-like earmold.  5)  Connector from the concha area through the fenestra to the hearing aid processor.  6)  The hearing aid processor.

 

Figure 8.  Healed condition from the auriculostomy procedure showing the open fenestra.

The tape and pin were removed each day, and the auriculostomy cleansed.  The pin was reinserted and hydrochloride of marfanil reapplied.  Following the first day, small circular band aids were used to cover the area, and in seven-to-ten days, the area was healed.  The hearing aid with it earmold was then utilized.

The opening remains open through continued use of the hearing instrument with its connector through the auriculostomy, with Figure 8 showing the healed and open fenestra.

 

Questions About the Auriculostomy Procedure

  • What style hearing aids were used? The specially designed hearing aids in use for this fitting are shown in Figure 9.

Figure 9.  A behind-the-ear (left) and an eyeglass hearing aid in use (right) with the Auriculostomy Hearing Aid fitting.  In the eyeglass aid, the wiring to the receiver is encased in a plastic tube that fits behind the ear to the fenestra, where it connects to the concha portion of the connection.

 

  • Who performs the work? The office surgery is performed by a qualified physician.  The taking of the ear impression at the time of surgery is performed by a licensed hearing professional.
  • Where is the Auriculostomy performed? The procedure is performed in a physician’s office.
  • How long does it take? The process involved takes about 20 minutes.
  • Is it Painful?   The procedure is performed under a local anesthetic.
  • Is any special after care required? Very little and much of that which is required is performed by the patient.  No side effects were recorded.
  • Can the procedure be used with an aged individual?   However, physical ability to make the connection may be difficult for those with dexterity problems.
  • Can it be used monaurally or binaurally?
  • Can the aid be removed? Yes, by simply disconnecting the coupling between the aid and the canal mold.
  • What are the reactions of those who have had the Auriculostomy?   None regretted having it performed.
  • What if the results aren’t liked? The auriculostomy can have its edges surgically freshened and allowed to close – minus the cartilage.  No noticeable side effects result.

 

Editor’s Note:  This procedure was not widely used, restricted primarily to the Milwaukee, Wisconsin area.  However, it did receive substantial interest at the AAOO (American Academy of Ophthalmology and Otolaryngology) Annual Meeting in Dallas, Texas in 1975. 

 

 

References

  1. Bolger JV, Strzalkowski CW, and Staab WJ. (1975).    An alternate approach to the application of corrective amplification involving ear-level hearing aids.  Hearing Instruments, February, 1975, pp 14-15.
  2. Bolger JV, Strzalkowski CW, and Staab WJ. (1974).    An alternate approach to the application of corrective amplification involving ear-level hearing aids.  Telex Brochure, Telex Communications, Inc., Minneapolis, MN, December, 1974.