CLICK HERE for presentation handouts.
Bright and early Sunday morning, the 2012 AG Bell Research Symposium “From the Ear to the Brain” brought together leaders in the field of speech and hearing science for an excellent morning of presentations on the latest research, funded by the National Institute on Deafness and Other Communication Disorders and the Hearing Health Foundation. To open the session Tilak Ratnanather, a research scientist who happens to have a hearing loss, encouraged parents and professionals to, “Germinate the idea in the minds of teenagers who are deaf or hard of hearing to pursue a career in auditory research,” a worthy challenge for us all to keep high standards for our children and encourage them to consider careers in science.
Dr. Joseph Santos-Sacchi of Yale University lectured on “The Queens of Audition” — outer hair cells. HERE is a clip of a video Santos-Sacchi showed during his presentation on how OHCs (Outer Hair Cells) move when stimulated by sound. Inner and outer hair cells int eh cochlear are connected by a lipid bilayer and work like a non-linear capacitor. Santos-Sacchi’s work identified the prestin protein as the “motor” that drives cochlear amplification. Prestin “pushes” the Organ of Corti and is essential for the transmission of sound from the inner ear to the brain.
Dr. Jont B. Allen presented on research he conducted in conjunction with Andrea Trevino and Woojae Han at the University of Illinois, Urbana-Champaign on “Speech Perception and Hearing Loss.” Dr. Allen and his team investigated consonant errors in people with typical hearing and people with hearing loss — what acoustic information makes the difference between hearing sounds correctly or confusing them with another sound? They found variations in signal to noise ration (SNR) and the amount of timing and frequency information available significantly affected listeners’ ability to hear consonant sounds clearly. Dr. Allen and his team hope that the findings of their research identifying the acoustic characteristics that affect consonant perception will eventually be used to improve the ways in which we program hearing aids to enhance users’ speech perception abilities.
Dr. Michael Dorman from Arizona State University spoke about “The Restoration of Speech Understanding by Electrical Stimulation of the Auditory System.” He presented research from Bichey and Miyamoto (2008) on the quality of life benefits of bilateral cochlear implants in late-deafened adults. Their research found that CIs vastly improve the quality of life for recipients, because speech understanding, “the holy grail,” allows CI users to participate more fully in the world at large. Dorman and his team found the best results in speech perception when single electrodes in the electrode array stimulated restricted and nonoverlapping portions of the spiral ganglion. This allowed for more true-to-pitch stimulations and a reduction in tones sounding “fuzzy.” He also noted that a future trend in cochlear implantation may be patients who are Bi-Bi — bilateral cochlear implant users with bilateral retention of some residual acoustic hearing. With improved surgical techniques, patient are able to maintain more low-frequency acoustic hearing, while benefitting from improved access to high frequency sounds with a cochlear implant. Electric-acoustic CI hybrids may be the wave of the future for patient who do not fit the traditional criteria of severe-profound hearing loss bilaterally.
Dr. Tonya R. Burgeson-Dana from Indiana University discussed “Spoken Language Development in Infants Who Are Deaf or Hard of Hearing: The Role of Maternal Infant-Directed Speech.” “Motherese” describes the special way in which mothers (and other caregivers) interact with infants, speaking to them with greater intonation, higher pitch, and more repetitions. It is also called infant-directed speech. From studies monitoring infants’ eye gaze and visual attention, they found that children with cochlear implants began to react differently to motherese vs. adult-directed speech vs. silence at about 9-12 months post-CI. Repetition is correlated with word learning in small children, so encouraging parents to use infant-directed speech, which includes more repetitions, is crucial for language development in children who are deaf or hard of hearing.