Beck: Good morning Dr. Osberger.
Osberger: Good morning Dr. Beck.
Beck: Mary Joe, it is a real pleasure to spend time with you addressing cochlear implants and related issues. I know you have an amazing wealth of knowledge and experience in this arena.
Osberger: Thanks Doug. Im happy to spend time with you, too.
Beck: Mary Joefor the readers not familiar with you, would you please tell me about your education?
Osberger: I received my doctorate from the City University of New York (CUNY) in Speech and Hearing Sciences in 1978, and I obtained my masters degree from Gallaudet University.
Beck: What was your dissertation on?
Osberger: I examined the effect of timing errors on the intelligibility of deaf childrens speech. Using digitized speech samples from deaf talkers, I shortened the duration of the vowels, then played the computer-altered speech to nave listeners to determine if there was an improvement in intelligibility. The results showed a positive effect and this early work sparked my interest in improving the speech skills of deaf children. Ultimately, we found that the most efficacious way to improve speaking skills in these children is through auditory feedback made possible through cochlear implants.
Beck: Whered you go after that?
Osberger: I was at Boys Town from 1980 to 1986 and then I joined the faculty of the University of Wisconsin-Madison for two years. After that, I went to the Indiana University School of Medicine Department of Otolaryngology, where I directed research studies on the benefits that children derived from cochlear implants.. Eleven years ago, I joined Advanced Bionics as Director of Clinical Research.
Beck: Thanks Mary Joe. One of the many relatively new ideas in CIs is the idea of current steering. I was hoping you might explain that concept?
Osberger: Current steering allows us to create synthetic or virtual channels between electrode contacts to deliver more frequency information to the cochlear-implant user. Prior to this technology, the number of frequency channels was limited by the number of electrode contacts in the array. Through simultaneous delivery of current to pairs of adjacent electrodes, stimulation can be steered to sites between the contacts by varying the proportion of current delivered to each electrode, thereby eliciting pitch percepts that are intermediate to the two electrodes. The number of distinct pitches that can be heard defines the number of spectral channels that can be perceived by the cochlear implant user. It is predicted that increased spectral resolution will improve music perception and enjoyment in cochlear implant users.
Beck: So you can electronically fill in the blanks more or less, by getting more spectral representation virtually, than you have acquired through additional electrodes and physical contacts points along the basilar membrane?
Osberger: Yes. Thats the idea.
Beck: Is it accomplished through a subtraction method? In other words is the lower frequency bioelectric information subtracted from the higher frequency information to create a difference representation?
Osberger: No. We actually stimulate two electrodes, and as they are simultaneously stimulated, by varying the current, we stimulate different populations of neurons. Different pitch percepts result from variation in the current amplitude, allowing better spectral representation than might be otherwise available.
Beck: So you create virtual channels interspersed with traditional physical channels yielding better spectral representation?
Osberger: Exactly. And, we are just beginning to evaluate a new feature for patients that increases spectral resolution through current steering. So the bottom line is that were not at the end of the sound processing journey, were at the beginning of new ideas and methods to better represent speech (and music) through cochlear implants. Doug, as you know, with our last major software release we substantially increased temporal resolution in HiRes sound processing, and now were refocusing our efforts on spectral enhancement via current steering.
Beck: Assuming these new protocols are successfulwhere would these new strategies present the most advantages for cochlear implant recipients?
Osberger: Probably the greatest impact would be in the most difficult listening situations, such as speech recognition in noise and in the perception of music.
Beck: That really would be fabulous. One additional benefit is that the changes were talking about are essentially software and processing changesso its likely to involve better solutions with the same hardwareor is that presumptive of me?
Osberger: Youre correct, at least as far as the HiRes 90K implant manufactured by Advanced Bionics Corporation, is concerned. The design concept of this device is that upgrades in sound processing are available through software or processor upgrades no new surgery or implant is required.
Beck: Mary JoeI wonder if you can tell me your thoughts regarding completely implantable cochlear implants (CICI) as far as when it might be available, and perhaps the advantages and disadvantages?
Osberger: Yes, well the CICI is likely the next major hardware advance in CI technology and the release date could be some 36 to 60 months away from commercialization. Of course, no one really knows, and there may be last minute challenges which no one is anticipating at this moment. Some of the issues related to hardware will include battery recharging, completely implantable batteries, implantable microphones and other miscellaneous CI related hardware.
Beck: In some respects, maybe this is analogous to CIC technology in that many folks think they want CICs as the idea and the promise are enticing. But then when they realize the trade-offs, some of those same people welcome BTEs!
Osberger: Yes, that might prove to be correct. I think some potential CI wearers would say theyd love a completely implantable device, but then Ill bet there are also patients that would not want to trade their current unit for the CICI, as they need and want the features available in their current technology. So the CICI may be available in 2 years, but it may take 5 or more years to develop the best alternatives and solutions.
Beck: Mary Joe, would you please discuss hybrids, meaning the crossover devices that incorporate hearing aids and cochlear implants in the same device.
Osberger: Yes, I can tell you a little about that. In some respects, hybrids represent the completion of a circle. Doug, when you were in Los Angeles in the mid-1980s you fit people with cochlear implants on one side and hearing aids on the other. Well, the hybrid allows a similar benefit in selected patients by delivering acoustic and electric stimulation to the same ear . Let me offer an example.Suppose you have a patient with 45 dB thresholds at 250, 500 and 1000 Hz, and at 1500 hes at 65 dB and at 2000 and 3000 and higher, his thresholds are beyond the limits of the audiometer? We know a hearing aid will not amplify sound above 2000 for this individual, but he would also benefit from amplification in the low frequenciesSo this person presents with an audiogram that might benefit from a hybrid cochlear implant delivering high frequency information, for example 2000, 3000 and 4000 Hz through the cochlear implant technology while using hearing aid technology for the lower tones, and doing so all-in-one device. This person represents a segment of the population that has hearing a little too good for a standard deep insertion cochlear implant electrode, yet his high frequency hearing is such that a hearing aid cannot supply the needed acoustic information..
Beck: And I know studies are underway to evaluate hybrids across the nation. Can you tell me your impression of the preliminary results?
Osberger: The preliminary results are very good. The Iowa group just published their results in Laryngoscope (May, 2005) and the results were impressive. They used a short (10 mm) electrode and they were able to essentially preserve the hearing for 20 of their 21 subjects, and the results on their speech audiometry and their speech-in-noise tests were also impressive when using the A + E (audio and electric) mode.
Beck: So do you think well be seeing more cochlear implant options for people with significant residual hearing?
Osberger: Yes. I think thats likely, and of course, one major question will be to define residual hearing with respect to these potential candidates.
Beck: I agree, and thats not going to be an easy thing to define. Another issue may be implants for people with mild or moderate hearing loss, but with inner hair cell damage, who perhaps just do not have the neural synchrony required to get a good result regarding word recognition via traditional hearing aid amplification.
Osberger: Yes, thats another as of yet undecided issue, but is certainly something ripe for a pilot study!
Beck:Mary Joe, thanks for your time today. I appreciate your insight and knowledge!
Osberger: Thanks you too, Doug.
For More Information on Advanced Bionics and cochlear implants visit, www.bionicear.com
Beck: Good morning Dr. Osberger.