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Interview with Bill Cole, Hearing Aid Pioneer by Marshall Chasin, Au.D.

Bill Cole

June 11, 2007

Topic: Early Development of Compression and Directional Microphones in Hearing Aids, Real-Ear Measurement and Digital Hearing Aids
Editor's Note: A scholarship was recently created by the University of Western Ontario to honor Mr. Bill Cole, a pioneer in the development in some of the first integrated circuits for hearing aids and who could be considered one of the fathers of compression in hearing aids. On behalf of Audiology Online, one of our Contributing Editors, Dr. Marshall Chasin from the Musicians' Clinics of Canada (, interviewed Mr. Cole to cover his many contributions and talk about the award.

Marshall Chasin: William A. Cole, also known as Bill Cole, is one of the most accessible people in the field of audiology. He is always willing to answer questions and provide insight that only comes with intelligence and years of experience. As President of Audioscan, Bill Cole, has dedicated his career to excellence and innovation in the field of audiology. Mr. Cole has left his mark of distinction on the hearing aid standards, audiology technology and has provided enriched experiences for future audiologists through his teaching. To this day Mr. Cole continues to freely provide assistance in engineering knowledge to all those who ask.

To honor Bill and all that he has contributed to the field, it was recently announced that a new award would be given in his name through the University of Western Ontario, in London, Ontario, Canada. The William A. Cole Award for Excellence in Audiology is dedicated to excellence and innovation in the field of audiology. It will be awarded to a student in the final year of the master's in clinical audiology program who has shown excellence in applying their knowledge to an area that has direct clinical applicability.

I wanted to chronicle the many accomplishments that have lead to this award, and so today I am sitting down with Bill to have a conversation about all of this. Congratulations, Bill. You have certainly earned this.

Bill Cole: Thank you, Marshall.

Chasin: I know that you are an electrical engineer. How did you end up in the hearing aid field?

Cole: It was largely serendipity, I suppose. As a teenager, I was interested in both electronics and audio. I designed and built my own vacuum tube amplifier and speaker enclosures and had one of the earliest stereo tape recorders. There were no audio or acoustics courses at Canadian universities, and I had a scholarship at the University of Waterloo so I became one of the early students in their co-op electrical engineering program. One of my co-op job placements was in a research lab working on the development of high-speed transistors, which led me into microchip manufacturing at Northern Telecom upon graduation. That eventually led me to Westinghouse Canada which had acquired the manufacturing rights to an integrated circuit originally developed for use in Zenith hearing aids. In 1970, I was given the job of designing a new generation of integrated circuits for hearing aids, and that got me back to audio in a way that I could never have imagined.

Chasin: I know that you hold six US patents related to hearing aids. Was this Westinghouse Integrated Ccircuit (IC) a linear hearing aid circuit?

Cole: No, my first integrated circuit design was a compression IC, the WC501. It was the first compression IC developed for a hearing aid, and it made it practical for many hearing aid manufacturers to offer compression hearing aids to their customers. That design was awarded a Canadian patent, and several linear circuts for both low- and high-power hearing aids then followed. Over the years, the Westinghouse Canada semiconductor group eventually became Linear Technology Inc., which eventually became Gennum, while the WC501 and its descendants continued to be used in millions of hearing aids and other low-voltage devices.

Chasin: I understand that you didn't join the spin-off to Linear Technology right off, but decided to join Unitron Industries.

Cole: Yes, when Westinghouse Canada decided to divest itself of the semiconductor group, the future looked pretty uncertain, and the opportunity came along to move to Unitron. I was their first engineer, although I hasten to point out that they already had some fine technicians working there.

Chasin: I understand that you designed a directional hearing aid while at Unitron in the early 1970s.

Cole: Yes, but my first design job was to develop what turned out to be the first BTE hearing aid with input compression: the Unitron 205. This eventually became the 295 and the 905. The only other input compression hearing aids around were the body-worn types. I learned a lot about hearing aid design during that project. I still have a Unitron 205, and I think it still sounds better than a lot of modern hearing aids.

Over the next few years, we built a new development lab where we had an anechoic chamber and one of the first KEMAR manikins. In 1975, I published an article on the difference between coupler gain and "functional" gain measured on KEMAR (which later became known as simulated insertion gain). One of my conclusions was that you could not properly fit a hearing aid without some way to measure this gain on an individual ear, and I could not see how this would ever be clinically feasible.

At that time, we were also working on directional hearing aids. We found that if you made them highly directional, people were at risk when out-of-doors. Because of cost and size, it was not possible to contemplate putting two microphones in a hearing aid; Ultimately, switching between directional and omnidirectional modes meant closing off the rear microphone port, which dramatically altered the frequency response. I came up with a scheme, which we patented, for adjusting the effective port spacing, allowing the polar pattern to be changed by moving a slider. That was the Unitron B500, and I have to say that it was a great idea, but also a great failure. It was physically large and had sharp corners and flat planes - very ergonomic but not very appealing.

Chasin: And then you left Unitron in 1977 and joined your previous colleagues who were now at Linear Technology?

Cole: Yes. My youngest son was born that year, and I wanted to spend more time at home than I had been able to when my other children were growing up. I was looking for part-time work, and Linear Technology was flexible enough to offer me a part-time position so that I could commute and work for them, three days a week. I was there until 1984.

Chasin: I understand that you were awarded four patents while you were there and also designed the first noise reduction circuit for hearing aids.

Cole: During that time, I received four patents on low-voltage circuits that could be used in hearing aids. The noise reduction patent was a case of serendipity. There were BILL (bass increase at lower levels) and TILL (treble increase at lower levels) circuits out at that time and I was working on a two-channel system with compression in the high frequency channel. I was listening to the circuit in my basement office when I suddenly realized that I could no longer hear the furnace running, yet nearby speech was very normal. It sparked a lot of interest in the consumer electronics area as well as in the hearing aid field.

Chasin: I do recall seeing that breadboard in a back room someplace at an ASHA convention. I understand that you left Linear Technology in 1983, along with your business partner, Jim Jonkman, to start up a company called Etymonic Design, Inc.- a product development firm. What are some of your accomplishments there?

Cole: Let me begin by saying that there is no connection between Etymotic Research Inc. and Etymonic Design Inc. Mead Killion and I started our companies within a couple of months of each other and, quite independently, picked similar names. We agreed to co-exist and put up with the occassional mixup in phone calls and orders.

Regarding the accomplishments, they were not mine, but rather were joint efforts with Jim and with other members of our team as we grew. Our first project in the hearing aid area was the mechanical, acoustic, and electronic design of a power BTE for Miracle Ear. They then asked us to propose an application of new technology to hearing aids and we proposed an analog, digitally-programmable hearing aid. We developed the world's first digitally-programmable ITE hearing aid in 1985, along with a hand-held programmer, and ran early pilot studies with them. Before that was finished, we were asked to develop a programmable BTE for Audiotone which Miracle Ear had just acquired. This turned out to be a lot more difficult. I believe it was called the "Dolphin". After that we got involved in Project Pheonix, which was the world's first digital hearing aid. We designed the analog input and output sections of the system. At that time, the digital part had limited dynamic range, and one had to compress the input to avoid overloading the A/D converter. We also developed an IC version of the trademarked Adaptive Compression circuit for Telex.

Chasin: The two-time constant circuit?

Cole: Yes, with Harry Teder. Another major project was the first headworn cochlear implant stimulator for the House Ear Institute, which involved all the mechanical and electronic design and prototyping for a replacement of the body-worn processing pack. This was a dual-channel processor driving a single electrode and was overtaken by multi-electrode implants before it got past the prototype stage. I also had some minor involvement with the K-AMP.

Chasin: Surely more than "minor". Your initials are on the K-AMP chip.

Cole: Yes, my initials are on the chip, but that is more a testament to Mead Killion's generosity than my contribution. My role was to share with the team some of the things I had learned about low-voltage, low-current design and help eat chinese food and pizza late at night. I developed the output stage but about that time, the class D receiver became available, and my output stage was therefore never needed.

Chasin: The K-AMP still remains my favorite hearing aid of all time.

Cole: Well, there's no question about it. I think it still sounds better than many of the hearing aids out there today.

Chasin: In 1989, you had to eat your words, because in the mid 1970s you had written off real-ear measurement as never being clinically feasible.

Cole: We actually started development in 1987. This was really the result of seeing a lot of our creative energies failing to result in viable products due to of forces beyond our control. After examining options, with the help of a business consultant, we decided there was a need for a portable HAT/REM system at a price people could afford; we decided we could design, manufacture, and market it. Recognizing that the confusion between Etymonic Design and Etymotic Research could become an issue, we trademarked Audioscan® and introduced the Audioscan RM500 in 1989. It was a reliable, durable system that people found easy to use, and it kept going and going. As hearing aids evolved, we continued to find innovative ways to test them and provide people the information they needed to successfully apply them. However, as digital technology became more sophisticated, we could see that there was a need for a new generation of testing technology.

In 2001, we introduced the Audioscan Verift as our first desktop HAT/REM system. It was the first system to replace the conventional tone and noise signals with digitized real speech samples that were accurately controlled in the sound field for repeatable measurements and analyzed in such a way that results could be directly compared to behavioral measures of hearing. It was also the first hearing aid analyzer with dual speakers and a patented test signal which allows the directional response of hearing aids to be tested and displayed in real time without the need to disable compression or adaptive features.

Chasin: I know that in addition to all of your accomplishments- input compression ICs, low-voltage, low-current drain ICs, directionality, real-ear measurement test equipment- you are also very active with ANSI and IEC technical committees.

Cole: I have been involved since the mid-1970s. I am involved in the IEC hearing aid standards committee, the audiometer standards committee, and the joint IEC/ISO committee on real-ear measurement. I also chair the ANSI committee on real-ear measurement, and I am on the ANSI hearing aid committee as well.

Chasin: Is there anything that you are not involved in?! My first question was to have been "how does an engineer end up having an audiology award named in his honor?" but listening to all of the various aspects and innovations in which you have been involved, the answer is pretty obvious. I know that you are an honorary professor at the University of Western Ontario, and it's well known in the field that if someone wants to know something, we just have to ask Bill.

Cole: I must say that I have basically done things that were fun, and although I have always worked long and hard, I have done things that I have enjoyed. Getting into the field of audiology has been great because it has allowed me to combine my early interests to do something that improves peoples' lives. That is really the most rewarding thing.

Chasin: Thank you, Bill.

If you would like more information about, or to make a donation in support of the "William A. Cole for Excellence in Audiology" please contact:

Maija Craig
Development Officer, Faculty of Health Sciences
The University of Western Ontario
Arthur & Sonia Labatt Health Sciences Building, Suite 200
London, ON N6C 2N9
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Bill Cole

Hearing Aid Pioneer