Here is a closeup photo of a pair of HAS units
These are the System III Amplifiers [ with one unit opened ].
These were the last HAS units made, they were designed in 1982.
The History of the Hearing Audio System...
I started making the HAS in 1977, when by chance, I met the author Richard Rosenthal, who came by Teachers College and requested testing of this "aid". His unit was a box about 6" x 5" x 3" ( 15.3 x 12.7 x 7.6 cm. ) in size, weighing in at about half a Kgm. He wore it on his chest and was quite a sight! We had no way to easily test this unit, which by the way was reportedly made for the C.I.A. by some contractor people for spying stuff. These contractors, they made these "boxes" for some of the foreign countries too, this was back in the 1970's, remember ??
Anyway, I convinced Richard that I was interested, and since I had a background in electronics and audio, for many years, I was truly interested. So I made an appointment to visit him at his home, and I tried his "unit" on and we talked for about a half hour. And when I took the unit off, for the first time, I realized that I did have hearing loss. The audiological charts had always been around so I knew the numbers and the lines and the curves by heart, but I had never actually "EXPERIENCED" it before. Well while I had that contraption on, I finally knew what it was like to have normal hearing, and then when I took it off... I knew.
I managed to convince Richard to let me take the unit apart, and I studied it for some time, maybe half an hour. I told him I could probably duplicate it with a bit of work, maybe making some improvements in the size / weight ratio. After a few months I had the first HAS unit ready, it measured 4" x 2 1/2" x 1 1/2" ( 10.2 x 6.4 x 3.8 cm ) and weighed about half what his original C.I.A. unit weighed. Some five years later, my later HAS System III Units were 3 1/4" x 2 1/4" x 1 5/8" ( 8.25 x 5.7 x 4.1 cm ). Bear in mind that most of this size and weight was due to the batteries. The original HAS unit worked on 18 Volts of small nicad rechargeables strung together, or two nine volt replaceable rectangulars, while the later units worked on one 8.4 volt nicad.
Most of the HAS units were pseudo-binaural devices, one microphone, and dual headphones feeding both ears. I had prototypes for high and low impedance headphones. It used to take me over a week to assemble and test each unit, which I sold, back then for $300 without the mic or phones. Richard insisted that the best microphone to use was the Sennheiser, with the removable heads, this allowed you to put on an omni-head, a cardioid-head or a shotgun-head. This refers to the pattern of sound pickup / rejection. This microphone kit of the Sennheiser K3U / ME-20 / ME-40 / ME-80 heads cost well over six hundred dollars as I remember, and that was the wholesale price. Incidentally, that K3U/ME-80 microphone was often used by TV reporters for their on site news reports because it did so well in windy situations, especially if you had the optional foam windscreen.
Considering the cost of parts and the time and labor, the HAS never really did make a profit. But I was doing it to try to help people, hear better, not get rich.
I stopped making the HAS devices back in 1982, after spending five years attempting to tell the world that it existed. The Net wasn't around and I had no access back then and really didn't get anywhere with it, but a few people came by from across the country to try the units out. As I recall, all of them went home with one..
Programmable HA's are perhaps the only improvement in a very long time. I hate to brag ( well just a little ) but my first HAS [ 1977 ] had a switch which allowed for flat frequency response or high frequency emphasis (HFE). Later units had even more. The equalizer on the System III units, circa 1982 had twice the battery life of the older ones, and added eq functions - three switches with multiple positions, which did two levels of HFE, two levels of low frequency cut (LFC), and a high frequency cut (HFC). This allowed something on the order of two dozen possible instantly repeatable frequency response curve selections. Since the center frequencies were purposely not matched, on all these EQ controls, using one setting was different from using any of the others, so they mixed and matched, to provide whatever adjustment was necessary for the particular acoustic environment and hearing loss, in any given situation. So I consider the HAS to have been the first "programmable hearing aid".
Now all was not perfection. The basic HAS amplifer was nearly the size of a walkman, and it needed an external mic and headphones. So it resembled an FM system without the "FM" part. Another limitation, or feature if you will, was that its SPL output was limited, very much to below 110db SPL. Feedback was also problem, so mostly it was for the mild to moderate group.
The basic HAS amplifier frequency response, at full power, or below, extended from 10 hz. to 60,000 hz. flat, as measured on an oscilloscope. What it excelled in was phase shift. There basically was none, it could pass a respectable 10Khz. square wave, which means very low levels of intermodulation distortion and transient forms of IM.
Unlike the stick-it-in-your-ear type of HA, which has distortion so high, it often stays at the 100% level, regardless of the input signal level or frequency, how can companies call that an amplifier ??? I'd call them distortion generators, which is precisely how conventional hearing aids sound. As for phase response, in HA's it often exceeded 360 degrees of phase shift, in the passband, which wasn't very wide: 600 - 3000 Hz.
Again, how can that type of product help a person, when it limits what sounds can get through so drastically, altering and distorting the hell out of what goes through the passband, ( some parts of speech ) and mixes up the phase and time relationships of the sounds that do make it through. Speaking of the sound that comes out; we are talking about putting a [now] very badly distorted, but louder sound, into an already impaired ear, and that loud sound will cause the ear's transformer type hearing mechanisms to distort more, and frankly, it just doesn't work. Well, to some degree it does, only due to the incredibly redundant capabilities of the human ear.
I was an Audiology Major in College and Graduate School. The people in the Graduate Program in Audiology didn't like my views, my HAS concept, or my being hearing handicapped, so instead of graduating me, they kicked me out. In the process of doing that, Teachers College violated their own written rules and regulations, but the US Department of Education, Office of Civil Rights (government assholes) let them get away with doing just that.
Steven L. Bender :-)
This page is under construction ( Like software, the job is never done!....)
Last Update - 03-31-99 4:15 AM