On May 8, 1998, Jont Allen (CTO at Mimosa Acoustics) gave a "lecture" to Mead Killion (President/CTO at Etymōtic Research) at Mead's request, on the history of Sysid and CUBeDIS. It was recorded and transcribed at the time, and sent from Mead to Jont as a fax. For those of you interested in acoustics history and historical documents, here is a transcription of non-proprietary excerpts from the fax.
Some background is necessary: Jont worked at Bell Labs in the Acoustics Research Dept., where he worked on measuring distortion products from cats (and humans), and developed some very basic computer software to allow this to be done in an efficient manner. The entire package was "given" to Etymōtic research, to sell. This is that story...
Visit from Jont Allen
May 8, 1998
I took a course on acoustics from Frank Romanoff who developed the 2 cc coupler and the telephone artificial ear. In 1970 when I came to Bell Labs he taught this course on acoustics and that's where I learned about acoustics. He told me that during WWII that they developed signal-averaging techniques for war work in sonar for looking for submarines and that it was highly secretive government project and technique. For many many years, he felt that it was still secret, which of course it wasn't. But he looked guilty when he talked about it, which I thought was pretty funny. In 1977 I went to a conference in Münster, Germany, and Yost Eggermont, who is now in Calgary, was at that conference, and I learned that one of the pieces of work that he did, that was very interesting, was that he used synchronous averaging with tone bursts and then masking noise, so they would take a high-pass masking noise and a click, or you could use a tone burst and try to do ABR testing and that would make it frequency selective. They would use stop-band noise and a click or they would use tone bursts. The kinds of stimuli that they were using were varied; they weren't just using clicks. They had been using time averaging in hearing for a long time. This is not new technology. In about 1980-82 I made an arrangement to give a computer to Wash U where Duck Kim and Charlie Molnar were there and I wanted to do recording from the auditory nerve and we agreed that we would send a computer there. I had a guy by the name of Ashouk Ranaday working with me and we wrote the first pass SYSID package. It was very primitive. He wrote the assembly language driver that ran on the data general mini computer that would allow us to do real-time synchronous averaging. It was the beginnings of SYSID. Then Ilene Bush Visniac spent the summer with us and we gave her the project of writing SYSID and she produced the application program. SYSID synchronously averaged and you could put out either a tone burst or a tone, or a click, or white noise, synchronously average the response, and then FFT the response. If you are putting out a chirp you could deconvolve the chirp and correct for the phase of the stimulus so you would get the impulse response. So then for commercializing SYSID, after I worked on the hearing aid project (which became the ReSound hearing aid in 1985), that's where I started using PCs during the ReSound hearing aid development, then the AT&T hearing aid development. Vincent Pluvinage was involved in that. We built a special purpose board that plugged into the PC. That was Vincent's first job was to build the plug-in board. Later we turned it into an Arial board but it was strictly for the internal purposes of the hearing aid. While we were developing the hearing aid, we needed hardware; we needed electroacoustic measurements badly so I said we are not going to buy a mini-computer for this project as there is just too much maintenance. Let's just get a PC. We'll build a plug-in board with high quality A/D and D/A, and we'll port SYSID code that Irene Visniac had written and that I had supported
for the many years. Thus in 1985 we had a PC version of SYSID, an internal version, working on our own private board. (Mead: That computer, for the record, became ReSound intellectual property, and I was instrumental in getting it from Bell Labs into a commercial operation somewhat later.) Resound bought the rights to SYSID. They didn't own the copyright or anything, but they had the rights to use it, along with all of the other software, so they took copies of all the software. Now whether they still have those copies or not I can't attest to, but it was commercial with ReSound. It was outside AT&T. So I had about 10 of these proprietary boards and they are all wire-wrap and every time I brought one up I had to find out where the missing wires were (out of 5000 wires). It would take me the whole day to get one of those boards to work; to trace down the hardware, find out which chip had a missing wire. I couldn't stand it. It was an incredible waste of time. I was looking for a commercial board that I could port the software. In 1986, I believe that's the date because in 1987 I ran ICASP (International Conference on Acoustics Speech and Signal Processing) the year prior to that ICASP, the meeting was in San Diego. I met Tony Agnello. He was president of Arial. I saw their products in the Exhibition Hall. I said you have a nice board that is perfect for my application. Would you help me port the software onto your board? His company was only a few miles away from Bell Labs, so when I got home to NJ, he came over for one evening and I showed him how our board worked and what the software did and gave him a complete spec, and within two days he had a working driver for the Arial board which all I had to was call from my program which was a simple interface, very clean. It took the code which was already compiled for the PC and ported it to his board. That was prior to the 1987 ICASP.
We had been talking about SYSID. Meanwhile before 1985, before the hearing aid project, CUBDIS existed internally. I worked for five years at Columbia Presbyterian Hospital between 2-5 days per week doing cat experiments, measuring neural responses, cochlear microphonic, ear canal pressure. That's where I started doing acoustic impedance work. That's the real reason why SYSID existed was so I could do all the experimental work. As soon as David Kemp announced that you could measure distortion products in the ear canal and Duck Kim announced it...
(Kim actually gave David the idea. That's an interesting story: David Kemp got the idea from Duck Kim, who was looking at propagated distortion products on the basilar membrane. They may have jointly had the idea, but they may have said that if it's on the basilar membrane, it's got to be in the ear canal. They both went home and measured it and there it was. Kemp got to press first and we know he got his publications in. David was looking at click evoked and was measuring it from the ear canal. His patent went in as early as 1977. But the actual measuring of distortion products that has a little bit later history.)
Paul Fahey and I started measuring distortion products in the cat around 1984 and it turned out that we didn't know why they were there and how meaningful they were. Since we could do it, we did it. That was our philosophy.
v2 updated July 2015