by Bob Zurek
On February 20, 2003 Dr. Gina Geissler gave a presentation to the AES Chicago Section titled "The Mechanics of Hearing Loss: Impact on Sound Perception with Hearing Aids and Cochlear Implants." Dr Geissler began her presentation by going over the pertinent anatomy and physiology. She covered the construction of the inner ear, and described the function of the inner and outer hair cells. She went on to discuss which portions of the cochlea picked-up which parts of the audible spectra. Dr Geissler then discussed the way in which the human ear performs phase locking for frequencies under 5000Hz, and can fire at any portion of a cycle for frequencies above 5kHz. She also pointed out that an increase in loudness is represented by the cochlea as an increase in nerve firing rate along with more cells firing. Dr. Geissler then discussed how hearing loss is measured, and how to read an audiogram. She discussed sensorineural and conductive hearing loss, and that the best treatment for hearing loss is prevention. She covered the application of hearing aids and cochlear implants, which directly stimulate the nerve fibers. Finally, Dr. Geissler brought up that there is currently research being done in the areas of short electrode arrays for high frequency use in conjunction with acoustic reinforcement for low frequencies, middle ear implantable hearing aids, and experimental brain stem implantable hearing aids. The presentation concluded with a question an answer session.
