By Anika Ayyar
Despite severe hearing difficulties, William H. Gates Sr. sat listening to his son, Bill Gates, deliver an acceptance speech after winning a Lasker Award for Public Service in 2013. He was able to participate in this momentous occasion thanks to his cochlear implant, an electronic device that simulates the functions of the cochlea (a cavity in the inner ear) by transmitting sound signals to the brain.
Coincidentally, three of the masterminds behind this very device were also present at the same ceremony, as they themselves were being awarded Lasker Awards for their work developing the modern cochlear implant. Blake Wilson, one of these scientists, noted during his speech at Duke last week that it was quite an experience for them to watch a device they had pioneered transform a personal interaction between William Gates Sr. and his son, right before their eyes.
Rewind 50 years, and few people would have paused to even consider the possibility of such a device that could capture sound signals and make them audible to individuals whose ears were damaged. Physiologist Merle Lawrence stated in 1964 that stimulation of auditory nerves would never result in perception of speech, while Rainer Klinke, a German neurophysiologist, went as far as to claim that “from a physiological point of view, cochlear implants [would] not work”.
Luckily, Blake Wilson thought differently. Starting in the 1980’s, he worked with teams across the globe, from the US, to Belgium, to Australia, to develop an innovative device that was able to process sound waves. As of 2015, this innovation has restored hearing capabilities to more than 450,000 individuals.
The path to generating an effective cochlear implant was characterized by continuous discovery and improvement. The first step in the process was simply to build a safe electronic device that had a lifespan of many years. This device was engineered to generate artificial electrical stimuli that triggered neurons in deaf individuals, whose sensory cells do not respond to the body’s chemical signals.
As the diagram on the right shows, both external (radio receiving and transmitting coils, processing chip) and internal (an array of electrodes around the helical structure of the inner ear) components work together in a cochlear implant to allow for speech recognition and hearing capabilities without the functionality of the cochlea’s natural functions.
Once scientists successfully engineered a device that stimulated the inner ear without causing any harm, teams in Palo Alto, Vienna, and Melbourne worked to enhance the implant by utilizing the tonotopic arrangement of the human auditory system. Stanford Professor Blair Simmons discovered that cadence, in addition to place of stimulation, was an important aspect of auditory signals, and he spearheaded experiments that sent different pulses to different electrodes in order to create a variety of perceptions of pitch.
By 1988, the NIH said that 1 in 20 patients who had received cochlear implants were able to carry out normal conversations without lip reading- a phenomenal accomplishment. The Consensus Statement also suggested that multichannel implants might be more effective than single-channeled ones, an idea that brought Wilson from Palo Alto to Duke in 1989, where he began to research multilateral stimulation. With support from the Research Triangle Institute, as well as members of the Duke community such as Dean Katsouleas of the Pratt School, Wilson was able to provide bilateral electrical stimulation to patients, by combining electric and acoustic methods for people who had residual, low frequency hearing. He also worked with colleagues to compress the range of sounds in the environment to a narrower range that could be transmitted to patients, by using filters to divide sounds into different frequencies.
Together, these prominent advances as well as numerous others fueled the evolution of the modern cochlear implant, which is projected to reach more than one million deaf and hearing-impaired individuals by 2020.
Listening to Wilson describe the history and progress of the project made it clear that the modern cochlear implant is not only a revolutionary creation in itself, but also that it holds enormous potential as a model for further development of other neural processes, such as restoration of vision and balance. Perhaps the most inspirational part of Wilson’s presentation however, was his description of the profound joy experienced by patients, doctors, and families whenever a cochlear implant restores auditory capability to an individual who otherwise never dreamt it possible to be able to hear.
Blake Wilson can be contacted at firstname.lastname@example.org
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View the entire lecture, with introductions by Provost Sally Kornbluth and Dean Tom Katsouleas of the Pratt School of Engineering. (1:08)