Interview with Sigfrid D. Soli Ph.D., Vice President of Technology Transfer and Head of the Department of Human Communication Sciences and Devices, House Ear Institute
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Topic: Research Trends, Synchronized Hearing Aids, the HINT and More
Beck: Hi Sig. Nice to meet with you again.
Soli: Hi Doug. Good to see you too. Welcome back to the House Ear Institute (HEI).
Beck: Thanks Sig, it's always amazing to come back and visit and I am honored to be here. Sig, I'd like to start with your education and professional background if that's OK?
Soli: Sure Doug. I went to the University of Minnesota and earned my Ph.D. in Experimental Psychology in 1979. My primary interest at that time, and through to this day has to do with speech perception. After earning my Ph.D. I joined the faculty of the Psychology Department at the University of Maryland, I received tenure after 6 years, and decided to leave the university to join the cochlear implant team at 3M. I was with 3M for 6 years and joined HEI in 1989. In fact, when I started at 3M, 3M and HEI were working together on cochlear implants, and I believe that's when you and I first met, about 1986 or so?
Beck: Yes, that seems to be about right. And if I recall, you were brought in to start up the hearing aid research lab. Do you recall the FDA hearings on cochlear implants?
Soli: Yes, I do. It was a dramatic moment for many of us. There was genuine concern about the risk of long term damage from cochlear implants, and the FDA panel was trying hard to do the right thing -- they were clearly conflicted. They had to deal with those very real cautions and concerns, but they also saw the obvious benefit implanted patients were receiving, and of course, they finally approved the implant. After the FDA had approved the cochlear implant, I recall mentioning to a colleague that it was the first time the FDA approved a device that substituted for one of the five senses! It was really a thrilling moment personally, academically and scientifically.
Beck: I remember the excitement when word got out that the FDA had approved it. There was a true feeling of excitement and wonder, and lots of controversy too!
Soli: That's right. Even though it was FDA approved, there was no consensus among deaf and hearing impaired people, nor was there consensus among professionals. Political, social and scientific issues were being considered and debated, and it was all very interesting.
Beck: Sig, please tell me your thoughts as to the changes at HEI in the last 15 years?
Soli: The changes have been enormous and have occured many times over. The building is beautiful -- brand new a few years ago. When I started, the labs were in the basement of the nun's residence, a block or two from where we're sitting at the moment. Dr. Linthicum had the world's largest temporal bone bank down there too, with the electron microscopy set-up and slides, and in fact, that's where your lab used to be!
Beck: Absolutely, the auditory research labs were in the basement, and I'll never forget that ventilation system, which was fairly dubious! But the work going on here was amazing...We did hundreds of bench tests with cochlear implant and hearing aid patients while colleagues were "digitizing" speech samples in the basement research lab to create better test materials. In restrospect, it's amazing to consider the quantity and quality of work accomplished at HEI. What about the current scientific focus? What are you working on?
Soli: Well the focus has come full circle. When I got here, I think we had about 75 people, and we were somewhat focused on behavioral sciences. Now, 15 years later, with 175 people, the focus is on the biological aspects of hearing and hearing loss. We're doing research now more on the cellular level, hair cell regeneration, genetics, and other topics along those lines. The behavioral sciences are still here too, but proportionally, we're more in alignment with current trends in science and medicine, and again, focusing more on the biological aspects. We're working on device and algorithm development for air conduction and bone anchored hearing aids, middle ear implants and other hearing technology too. A lot of the work we do has to do with developing hearing aid fitting techniques and assessing benefit of those instruments too.
Beck: Which gets me to the speech tests you've developed here at HEI, such as the HINT, and the ability to assess benefits from binaural amplification.
Soli: Yes, thanks for mentioning that. There's a substantial body of research literature in the JASA, and other journals, that indicates our ability to hear in noise has a lot to do with binaural and directional hearing. And we're working to take that to the next level.
Beck: Do you think we'll soon be seeing the fitting of "in-tandem" binaurals? In other words, currently we fit two independent hearing aids on the two ears, but the argument has been made that if the two hearing aids were somehow "linked" to each other, much as natural ears are linked through the central nervous system, with respect to loudness, amplitude, spectral issues, phase or some other "linking factor," we might secure additional binaural benefit?
Soli: Yes, well this is a terrifically interesting topic. It's so new that we haven't yet agreed upon a name or an acronym to represent it - maybe we'll call it "in-tandem" or "linked" or maybe "synchronized." We'll have to see what the name becomes. But in the meantime, I really don't know the answer! The first question may be to better understand what the binaural system is capable of, and then we would have a better chance of maximizing that ability. Nonetheless, I think the reason we don't maximize binaural hearing with instruments available today may have more to do with the limits of the current bandwidth. The most important information for recognition of speech in noise, or speech intelligibility, has more to do with high frequency hearing. If the hearing aid is limited in bandwidth, you won't be able to perceive the high frequency cues that make it possible to do well in noise. Then again, despite some theoretical advantages to "synchronized" hearing aids, I'm not convinced we need to do that. We may resolve those issues through other avenues, like broader bandwidths, more accurate and responsive amplitude compression factors, and paying careful attention to temporal effects.
Beck: Interesting idea. So in essence, if we can really maximize the hearing aid's electroacoustic characteristics, maybe we don't need to "synchronize" hearing aids?
Soli: Maybe. The "rate limiting factor" may be the binaural ability of the individual, and we're not really sure how to measure that just yet. Linking the hearing aids may prove eventually to be necessary, but it seems to me at this moment, that we may have some other steps to accomplish first, to better determine whether or not we desire to link hearing aids together.
Beck: Which gets me to assessment tools, such as the Hearing In Noise Test (the "HINT" Test) which I believe was first published in the Journal of the Acoustical Society of America (JASA) some ten years ago?
Soli: Yes, you're right. We published it in 1994. Since that time we've developed PC-based administration and scoring tools, and it can now be administered using headphones for "virtual audio" and I think that was the first time virtual technology was used in audiometry.
Beck: Tell me if this will suffice....I should mention that the HINT is a speech reception test, which adaptively measures the listener's threshold of intelligibility in referenced noise. The scores obtained are based on issues and conditions related to binaural hearing and can measure "functional hearing" ability. This is very useful as a measure of performance while wearing and comparing different hearing aids, and different hearing aid programs within a single hearing aid.
Sig, for the readers that may want to obtain copies of the HINT, where do they turn?
Soli: Maico Diagnostics has it. People can call or e-mail Maico to purchase the HINT as a PC-based system or CD version. The HINT is fully developed and is available in English, North American Spanish, Spanish, Canadian French, Brazilian Portuguese, Portuguese, Korean, Mandarin, Cantonese and a few other languages too. So the HINT is quite versatile, and is commercially available in many of the most prominent languages.
Beck: Are the norms the same across languages?
Soli: That's a fantastic question. You see, this issue is extremely important for this type of test. Because this is an adaptive test, it can be normed on the normally-hearing population on each of these languages. And, if you compare the norms for English, Spanish and French, you can measure and report the norms, and pool the data across languages, and they really should be quite similar, and they are. Not entirely identical, but very similar. One other thing to consider, as you mentioned a moment ago, HINT thresholds are also useful to measure and evaluate the "distortion component" of sensorineural hearing loss. For clinical purposes, distortion loss issues are not usually diagnosed or used, but for device fittings, HINT thresholds can tell you the extent to which you may have improved or reduced the distortion factors via the particular device or program.
Beck: I think this is an important topic for many reasons, but one thing I'd offer-up here is that the HINT is one of only a few objective tools, that allows us to measure speech perception in an objective and repeatable fashion, in the worst possible "real world" scenario - noise! To me, that's very useful, and makes a lot of sense even beyond identifying the best fitting hearing aid, or the best circuit, but also as a counseling tool, to show what the hearing aid can, and cannot do!
Soli: Yes, I agree Doug. I think counseling and aural rehab aspects are important aspects of the HINT. Another new application for the HINT has to do with occupational medicine, and the ability to measure "functional hearing" in a variety of occupational listening situations.
Beck: Sig. We could probably go on and on for hours about the research at House, and in particular the HINT test, but I know I've gotta let you get back to it. Thanks so much for your time.
Soli: You're welcome Doug. Nice to see you again, and I'm glad we were able to get together.
Beck: Thank you too, Sig. I appreciate your time and insights, and congratulations on the excellent work you do.
-------------------
For more information on the House Ear Institute, CLICK HERE.
Soli: Hi Doug. Good to see you too. Welcome back to the House Ear Institute (HEI).
Beck: Thanks Sig, it's always amazing to come back and visit and I am honored to be here. Sig, I'd like to start with your education and professional background if that's OK?
Soli: Sure Doug. I went to the University of Minnesota and earned my Ph.D. in Experimental Psychology in 1979. My primary interest at that time, and through to this day has to do with speech perception. After earning my Ph.D. I joined the faculty of the Psychology Department at the University of Maryland, I received tenure after 6 years, and decided to leave the university to join the cochlear implant team at 3M. I was with 3M for 6 years and joined HEI in 1989. In fact, when I started at 3M, 3M and HEI were working together on cochlear implants, and I believe that's when you and I first met, about 1986 or so?
Beck: Yes, that seems to be about right. And if I recall, you were brought in to start up the hearing aid research lab. Do you recall the FDA hearings on cochlear implants?
Soli: Yes, I do. It was a dramatic moment for many of us. There was genuine concern about the risk of long term damage from cochlear implants, and the FDA panel was trying hard to do the right thing -- they were clearly conflicted. They had to deal with those very real cautions and concerns, but they also saw the obvious benefit implanted patients were receiving, and of course, they finally approved the implant. After the FDA had approved the cochlear implant, I recall mentioning to a colleague that it was the first time the FDA approved a device that substituted for one of the five senses! It was really a thrilling moment personally, academically and scientifically.
Beck: I remember the excitement when word got out that the FDA had approved it. There was a true feeling of excitement and wonder, and lots of controversy too!
Soli: That's right. Even though it was FDA approved, there was no consensus among deaf and hearing impaired people, nor was there consensus among professionals. Political, social and scientific issues were being considered and debated, and it was all very interesting.
Beck: Sig, please tell me your thoughts as to the changes at HEI in the last 15 years?
Soli: The changes have been enormous and have occured many times over. The building is beautiful -- brand new a few years ago. When I started, the labs were in the basement of the nun's residence, a block or two from where we're sitting at the moment. Dr. Linthicum had the world's largest temporal bone bank down there too, with the electron microscopy set-up and slides, and in fact, that's where your lab used to be!
Beck: Absolutely, the auditory research labs were in the basement, and I'll never forget that ventilation system, which was fairly dubious! But the work going on here was amazing...We did hundreds of bench tests with cochlear implant and hearing aid patients while colleagues were "digitizing" speech samples in the basement research lab to create better test materials. In restrospect, it's amazing to consider the quantity and quality of work accomplished at HEI. What about the current scientific focus? What are you working on?
Soli: Well the focus has come full circle. When I got here, I think we had about 75 people, and we were somewhat focused on behavioral sciences. Now, 15 years later, with 175 people, the focus is on the biological aspects of hearing and hearing loss. We're doing research now more on the cellular level, hair cell regeneration, genetics, and other topics along those lines. The behavioral sciences are still here too, but proportionally, we're more in alignment with current trends in science and medicine, and again, focusing more on the biological aspects. We're working on device and algorithm development for air conduction and bone anchored hearing aids, middle ear implants and other hearing technology too. A lot of the work we do has to do with developing hearing aid fitting techniques and assessing benefit of those instruments too.
Beck: Which gets me to the speech tests you've developed here at HEI, such as the HINT, and the ability to assess benefits from binaural amplification.
Soli: Yes, thanks for mentioning that. There's a substantial body of research literature in the JASA, and other journals, that indicates our ability to hear in noise has a lot to do with binaural and directional hearing. And we're working to take that to the next level.
Beck: Do you think we'll soon be seeing the fitting of "in-tandem" binaurals? In other words, currently we fit two independent hearing aids on the two ears, but the argument has been made that if the two hearing aids were somehow "linked" to each other, much as natural ears are linked through the central nervous system, with respect to loudness, amplitude, spectral issues, phase or some other "linking factor," we might secure additional binaural benefit?
Soli: Yes, well this is a terrifically interesting topic. It's so new that we haven't yet agreed upon a name or an acronym to represent it - maybe we'll call it "in-tandem" or "linked" or maybe "synchronized." We'll have to see what the name becomes. But in the meantime, I really don't know the answer! The first question may be to better understand what the binaural system is capable of, and then we would have a better chance of maximizing that ability. Nonetheless, I think the reason we don't maximize binaural hearing with instruments available today may have more to do with the limits of the current bandwidth. The most important information for recognition of speech in noise, or speech intelligibility, has more to do with high frequency hearing. If the hearing aid is limited in bandwidth, you won't be able to perceive the high frequency cues that make it possible to do well in noise. Then again, despite some theoretical advantages to "synchronized" hearing aids, I'm not convinced we need to do that. We may resolve those issues through other avenues, like broader bandwidths, more accurate and responsive amplitude compression factors, and paying careful attention to temporal effects.
Beck: Interesting idea. So in essence, if we can really maximize the hearing aid's electroacoustic characteristics, maybe we don't need to "synchronize" hearing aids?
Soli: Maybe. The "rate limiting factor" may be the binaural ability of the individual, and we're not really sure how to measure that just yet. Linking the hearing aids may prove eventually to be necessary, but it seems to me at this moment, that we may have some other steps to accomplish first, to better determine whether or not we desire to link hearing aids together.
Beck: Which gets me to assessment tools, such as the Hearing In Noise Test (the "HINT" Test) which I believe was first published in the Journal of the Acoustical Society of America (JASA) some ten years ago?
Soli: Yes, you're right. We published it in 1994. Since that time we've developed PC-based administration and scoring tools, and it can now be administered using headphones for "virtual audio" and I think that was the first time virtual technology was used in audiometry.
Beck: Tell me if this will suffice....I should mention that the HINT is a speech reception test, which adaptively measures the listener's threshold of intelligibility in referenced noise. The scores obtained are based on issues and conditions related to binaural hearing and can measure "functional hearing" ability. This is very useful as a measure of performance while wearing and comparing different hearing aids, and different hearing aid programs within a single hearing aid.
Sig, for the readers that may want to obtain copies of the HINT, where do they turn?
Soli: Maico Diagnostics has it. People can call or e-mail Maico to purchase the HINT as a PC-based system or CD version. The HINT is fully developed and is available in English, North American Spanish, Spanish, Canadian French, Brazilian Portuguese, Portuguese, Korean, Mandarin, Cantonese and a few other languages too. So the HINT is quite versatile, and is commercially available in many of the most prominent languages.
Beck: Are the norms the same across languages?
Soli: That's a fantastic question. You see, this issue is extremely important for this type of test. Because this is an adaptive test, it can be normed on the normally-hearing population on each of these languages. And, if you compare the norms for English, Spanish and French, you can measure and report the norms, and pool the data across languages, and they really should be quite similar, and they are. Not entirely identical, but very similar. One other thing to consider, as you mentioned a moment ago, HINT thresholds are also useful to measure and evaluate the "distortion component" of sensorineural hearing loss. For clinical purposes, distortion loss issues are not usually diagnosed or used, but for device fittings, HINT thresholds can tell you the extent to which you may have improved or reduced the distortion factors via the particular device or program.
Beck: I think this is an important topic for many reasons, but one thing I'd offer-up here is that the HINT is one of only a few objective tools, that allows us to measure speech perception in an objective and repeatable fashion, in the worst possible "real world" scenario - noise! To me, that's very useful, and makes a lot of sense even beyond identifying the best fitting hearing aid, or the best circuit, but also as a counseling tool, to show what the hearing aid can, and cannot do!
Soli: Yes, I agree Doug. I think counseling and aural rehab aspects are important aspects of the HINT. Another new application for the HINT has to do with occupational medicine, and the ability to measure "functional hearing" in a variety of occupational listening situations.
Beck: Sig. We could probably go on and on for hours about the research at House, and in particular the HINT test, but I know I've gotta let you get back to it. Thanks so much for your time.
Soli: You're welcome Doug. Nice to see you again, and I'm glad we were able to get together.
Beck: Thank you too, Sig. I appreciate your time and insights, and congratulations on the excellent work you do.
-------------------
For more information on the House Ear Institute, CLICK HERE.
